Guy Atkin's Independent Testing of PL-380 7.5" Loopstick
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Hello All,
This is forwarded from Guy Atkins, who apparently had a problem getting
this message posted to the Ultralightdx Yahoo site:
.
---------- Forwarded message ---------- From: Guy Atkins <dx@...> Date: Mon, Feb 1, 2010 at 4:56 PM Subject: Modding the Tecsun PL-380 with an External Ferrite Antenna - My Experience To: ultralightdx@... I've followed some of the recent discussion about modifying the PL-380 with the Amidon type 61, 7.5" ferrite rod that is commonly used with the hotrodded Eton E100 receivers. Having modified Kchibo D96Ls and Eton E100s with this useful Amidon item, I decided that it was time to try my hand at the Tecsun PL-380. I wasn't sure what
to expect regarding the optimum coil inductance and position of the coil on the
ferrite, since there's been a good amount of debate on this topic. Gary DeBock
claims an inductance around 554 uH is the best for all MW frequencies, and that
there's a "sweet spot" on the rod where an 81 turn coil of 40/44 Litz wire
provides this inductance, giving the strongest signals across the band with this
fixed position coil.
The SiLab Si4734
chip's datasheet indicates an acceptable 180-450 uH inductance range for the
antenna, and the chip tunes a varactor capacitor for best performance on each MW
frequency (resonating the LC circuit)... no manual adjustments at the factory
are needed. For the ULR experimenter this means there should be NO "best" position (sweet spot) of a coil on
the external Amidon ferrite rod, as long as the inductance is within 180-450
uH.
I dove into the
disassembly of my PL-380, very curious as to what I would find gives the best
signal gain with an Amidon rod modified receiver. Maybe there's be no difference
180 to 450 uH, just as SiLabs' data implies.
I removed the
small, flat ferrite antenna from the PL-380 and found it measured 239 uH,
clearly within the specified range.
An 81 turn Litz
wire coil (the recommended 40/44 style) with Amidon 7.5" type 61 rod was tried
next, mounted externally with the "piece of a carpenters level" trick that Gary
pioneered as a simple frame to support a slider coil
antenna.
It was quickly
evident that Gary is correct--there *is* a "best" inductance for the PL-380, and
it is far outside the range given in the SiLabs chip's documentation. I listened
to low, mid, and high-band MW stations for an audible peak and kept a close
watch on the RSSI signal numbers on the radio's display while sliding the coil
left and right (and taking average readings over a minute or so). With the coil
positioned at the ends, signals were barely audible, but rose quickly to maximum
levels at a location about 1-3/4 inches from the end of the rod to the first
edge of the coil. Beyond that distance, the RSSI values started dropping (but
not as quickly as they rose within the 1-3/4 inches from the end of the rod.) No
matter what MW frequency I tuned, there was one small place on the Amidon rod
where signals were strongest.
I taped the coil in
this "best" position, disconnected the antenna leads from the receiver, and
measured the resulting value. It was 533 uH! This number is very close to Gary's
claimed 554 uH optimum, and obviously beyond the 450 uH upper limit stated by
SiLabs for an AM broadcast antenna. With the coil moved toward the end of the
Amidon rod, I measured around 300 uH (all but the strongest signals were
inaudible with 300 uH inductance on the Amidon rod).
See below for a
short video (1 Mb WMV file) I made of the peaking of my local TIS station on 530
kHz using this PL-380 setup. It's a bit blurry, but the RSSI and SNR numbers can
be seen changing. I placed a triangle of black tape on the support frame
pointing to the "optimum" position of the left edge of the coil to help you
observe and hear the signal changes left & right of the best spot. It is
this position marked with the black arrow that results in a 533 uH inductance on
my setup.
Here are some photos and captions
of different steps of this PL-380 project: http://tinyurl.com/ycajpex Click on the thumbnail images
and use the PicasaWeb magnifying glass tool for up-close
views.
This modified PL-380 is as
sensitive as any slider coil E100 hotrod ULR radio I've built and used. I look
forward to snagging some TP DX with this little wonder! The multiple DSP
bandwidths are as useful as those on the Kchibo D96L, but the minimal soft mute
is an excellent benefit of the PL-380. I also appreciate the easy frequency
entry and the overall build quality of the Tecsun receiver.
So what do we conclude
about the "correct" inductance for the PL-380 antenna? First of all, Gary is
correct--an inductance of approximately 530-550 uH when used with the 7.5", 61
type ferrite material from Amidon and 40/44 Litz wire clearly provides the most
sensitivity. Why this is well out of the SiLab-recommended range of inductance,
I have no idea. Maybe it involves the physical size and ferrite mix of the rod,
along with the Litz coil parameters, although this contradicts what others have
said about the Si4734 chip automatically matching any 180-450 uH coil,
period.
Whatever
yet-to-be-discovered reason for the modded PL-380's behavior, I'm happy that
fellow DXer and Puyallup, WA resident Gary DeBock has shared his discoveries
freely with the rest of us. I'm sure he knew he'd get some "heat" for his
unorthodox claim about modding the PL-380. I commend him for not keeping quiet,
and for taking a risk to publicize his findings.
As a reminder, Gary's
article that details this modification to the PL-380 is found
here:
I'm sure others will
continue to debate theory vs. hands-on results with the PL-380 receiver, but if
you'll excuse me I have some DX to snag with this little hotrod from
Tecsun...
73,
Guy
Atkins
Puyallup,
WA
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Hi Scott,
Thanks for the clarification. I think if everyone had been clear on this
point originally, it might have saved a few "potshots" directed my way :-)
For those interested, Guy Atkins' modified PL-380 model is now the fifth
such unit to have received a 7.5" Amidon type 61 bar loopstick transplant, and
all of the models have been found (using an 81-turn 40/44 Litz wire
Slider coil) to have maximum AM sensitivity provided when the coil inductance is
somewhere within the 530- 560 uh range.
73, Gary DeBock
(in Puyallup, WA)
In a message dated 2/1/2010 11:23:22 P.M. Pacific Standard Time,
sdwillingham@... writes:
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sdwillingham
I think there is a bit of a misunderstanding here. The chip's datasheet
toggle quoted message
Show quoted text
indicates a range of inductance over which the chip's built-in varactor can successfully bring to resonance. This is neccessary, but not sufficient for calling the antenna "optimal". The choice of which inductance works "best" overall probably depends on several physical factors and usage patterns. But once chosen, the chip will automatically resonate the inductor, which eliminates the factory alignment procedure which has historically been needed. I don't think the inductance spec should be read as indicating that all inductances will perform equivalently; only that all within range can be resonated. As for the chip tuning inductors outside the specified range, please recognize that a datasheet is a guarantee of performance. In the case of integrated circuits, it is critical that a vanishingly small number of them fall outside the datasheet parameters when deployed in the field. No manufacturer can afford to scrap complex devices when one of many chips inside fail to perform as specified. So the numbers in a datasheet are all conservative, some are very much so. -Scott- ---------- Forwarded message ---------- The SiLab Si4734 chip's datasheet indicates an acceptable 180-450 uH |
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sdwillingham
Gary,
toggle quoted message
Show quoted text
Your results are interesting, but I think it would be good to take the experiment to the next level. A problem with your slider method is that it is well-known that loopstick Q is degraded when the coil is not centered. At the extreme ends, the effect is severe. I am afraid that your 81-turn coil may be handicapping the low-inductance values too much. A good experiment would be to slide your 81-turn coil to the middle of the ferrite and measure its inductance. Then compute two winding values that would produce coils with values of say 330 uH and 550 uH, _when_centered_. Test each centered coil over a range of stations over the band, strong and weak, carefully comparing RSSI and SNR. It is also useful to spot- check the general noise-floor at several points "between" channels. It is probably necessary to build the coils with connectors that are easy to swap in order to compare results without too much error due to time variation of propagation. (Be sure to retune the radio's frequency after each swap!) I think a comparison of centered coils with no difference besides number of turns will be educational and eliminate possible confounding factors. -Scott- --- In ultralightdx@..., D1028Gary@... wrote:
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Roy <roy.dyball@...>
Hi Garry Looking at the video of the coil being moved indicates that the all that is happening is that you are moving the coil away from a peak that has already been established from a previous tuning operation that has set the varactors capacitance to tune the loopstick at the black mark for the coils inductance at that position on the rod. It appears to me that the coil was originally tuned at the black mark then moved off peak before the video started. You cannot expect the Si4734 to track while moving the coil because it does not know the coil has moved and keeps the capacitance unchanged, but you have changed the inductance by moving the coil and of course the signal will rises and fall when you move the loopstick. Had the radio been retuned each time the coil was moved the Si4734 would have returned its varactor capacitance for the new inductance brought about by the movement and really the signal would not have changed by much more than about 3dbu across the rod. The only time the Si4734 changes its capacitance to match the loopsticks inductance is during a tuning operation and this was not done in the video. The capacitance does not change automatically when you slide the coil. The whole idea of the Si4734 is it is self aligning. And that is why you must step off and step back on frequency every time you move the loopstick. It would be very interesting to see the video redone showing the method described above because every time the coil was moved and the frequency retuned the audio and the signal levels (within about 3dbu) would have come back up. We must understand how this chip works and use this chip as it is designed and not copy old methods from completely different technology without applying them to this new technology correctly. I think there has been a misunderstanding as to the correct operation of how the Si4734 works and I now that criticism can be taken the wrong way especially when someone has put a lot of work into their results and presented them sincerely. I really believe that the video showing a peak signal on the rod is incorrectly presented and had the radio been retuned between movements it would have only shown how cleaver the Si4734 really is at realigning itself and not a signal dropping off from an established peak. Cheers Roy.
--- In ultralightdx@..., D1028Gary@... wrote: > > Hello All, > > This is forwarded from Guy Atkins, who apparently had a problem getting > this message posted to the Ultralightdx Yahoo site: > > > > > . > > > ---------- Forwarded message ---------- > From: Guy Atkins <_dx@..._ (mailto:dx@...) > > Date: Mon, Feb 1, 2010 at 4:56 PM > Subject: Modding the Tecsun PL-380 with an External Ferrite Antenna - My > Experience > To: _ultralightdx@... (mailto:ultralightdx@...) > > > I've followed some of the recent discussion about modifying the PL-380 > with the Amidon type 61, 7.5" ferrite rod that is commonly used with the > hotrodded Eton E100 receivers. Having modified Kchibo D96Ls and Eton E100s with > this useful Amidon item, I decided that it was time to try my hand at the > Tecsun PL-380. > > > I wasn't sure what to expect regarding the optimum coil inductance and > position of the coil on the ferrite, since there's been a good amount of > debate on this topic. Gary DeBock claims an inductance around 554 uH is the best > for all MW frequencies, and that there's a "sweet spot" on the rod where > an 81 turn coil of 40/44 Litz wire provides this inductance, giving the > strongest signals across the band with this fixed position coil. > > > The SiLab Si4734 chip's datasheet indicates an acceptable 180-450 uH > inductance range for the antenna, and the chip tunes a varactor capacitor for > best performance on each MW frequency (resonating the LC circuit)... no > manual adjustments at the factory are needed. For the ULR experimenter this > means there should be NO "best" position (sweet spot) of a coil on the external > Amidon ferrite rod, as long as the inductance is within 180-450 uH. > > > I dove into the disassembly of my PL-380, very curious as to what I would > find gives the best signal gain with an Amidon rod modified receiver. Maybe > there's be no difference 180 to 450 uH, just as SiLabs' data implies. > > > I removed the small, flat ferrite antenna from the PL-380 and found it > measured 239 uH, clearly within the specified range. > > > An 81 turn Litz wire coil (the recommended 40/44 style) with Amidon 7.5" > type 61 rod was tried next, mounted externally with the "piece of a > carpenters level" trick that Gary pioneered as a simple frame to support a slider > coil antenna. > > > It was quickly evident that Gary is correct--there *is* a "best" > inductance for the PL-380, and it is far outside the range given in the SiLabs > chip's documentation. I listened to low, mid, and high-band MW stations for an > audible peak and kept a close watch on the RSSI signal numbers on the > radio's display while sliding the coil left and right (and taking average > readings over a minute or so). With the coil positioned at the ends, signals were > barely audible, but rose quickly to maximum levels at a location about > 1-3/4 inches from the end of the rod to the first edge of the coil. Beyond that > distance, the RSSI values started dropping (but not as quickly as they > rose within the 1-3/4 inches from the end of the rod.) No matter what MW > frequency I tuned, there was one small place on the Amidon rod where signals > were strongest. > > > I taped the coil in this "best" position, disconnected the antenna leads > from the receiver, and measured the resulting value. It was 533 uH! This > number is very close to Gary's claimed 554 uH optimum, and obviously beyond > the 450 uH upper limit stated by SiLabs for an AM broadcast antenna. With the > coil moved toward the end of the Amidon rod, I measured around 300 uH (all > but the strongest signals were inaudible with 300 uH inductance on the > Amidon rod). > > > See below for a short video (1 Mb WMV file) I made of the peaking of my > local TIS station on 530 kHz using this PL-380 setup. It's a bit blurry, but > the RSSI and SNR numbers can be seen changing. I placed a triangle of black > tape on the support frame pointing to the "optimum" position of the left > edge of the coil to help you observe and hear the signal changes left & > right of the best spot. It is this position marked with the black arrow that > results in a 533 uH inductance on my setup. > > > _http://www.mediafire.com/?zdjhxmmmtyz_ > (http://www.mediafire.com/?zdjhxmmmtyz) > > > Here are some photos and captions of different steps of this PL-380 > project: _http://tinyurl.com/ycajpex_ (http://tinyurl.com/ycajpex) Click on the > thumbnail images and use the PicasaWeb magnifying glass tool for up-close > views. > > > This modified PL-380 is as sensitive as any slider coil E100 hotrod ULR > radio I've built and used. I look forward to snagging some TP DX with this > little wonder! The multiple DSP bandwidths are as useful as those on the > Kchibo D96L, but the minimal soft mute is an excellent benefit of the PL-380. I > also appreciate the easy frequency entry and the overall build quality of > the Tecsun receiver. > > > So what do we conclude about the "correct" inductance for the PL-380 > antenna? First of all, Gary is correct--an inductance of approximately 530-550 > uH when used with the 7.5", 61 type ferrite material from Amidon and 40/44 > Litz wire clearly provides the most sensitivity. Why this is well out of the > SiLab-recommended range of inductance, I have no idea. Maybe it involves > the physical size and ferrite mix of the rod, along with the Litz coil > parameters, although this contradicts what others have said about the Si4734 > chip automatically matching any 180-450 uH coil, period. > > > Whatever yet-to-be-discovered reason for the modded PL-380's behavior, I'm > happy that fellow DXer and Puyallup, WA resident Gary DeBock has shared > his discoveries freely with the rest of us. I'm sure he knew he'd get some > "heat" for his unorthodox claim about modding the PL-380. I commend him for > not keeping quiet, and for taking a risk to publicize his findings. > > > As a reminder, Gary's article that details this modification to the PL-380 > is found here: > _http://www.dxer.ca/file-area/doc_details/289-supercharging-the-tecsun-pl-38 > 0_ > (http://www.dxer.ca/file-area/doc_details/289-supercharging-the-tecsun-pl-380) > > > I'm sure others will continue to debate theory vs. hands-on results with > the PL-380 receiver, but if you'll excuse me I have some DX to snag with > this little hotrod from Tecsun... > > > 73, > > > Guy Atkins > Puyallup, WA > _http://fivebelow.squarespace.com_ (http://fivebelow.squarespace.com/) > |
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Hi Roy,
I really appreciate the clear fashion in which you (and Scott) explain the SiLabs chip's operation! You are correct; I did not realize that the chip tunes for proper inductance after it detects a change of frequency; I thought it "senses" the inductance continuously, and displays any signal strength changes during the "refresh" cycle of the RSSI indicator.
I'd forgotten about the maxim of best "Q" with a centered coil. After so many years of seeing stock loopsticks with factory coils positioned so far from center, I've not given it much thought. I like Scott's idea of starting coil winding right at the center, and seeing if there's any difference between a 330 uH and 550 uH coil.
The purpose of the black arrow marker in my video was simply to show the positioning of the coil for which I had previously found to give the best reception. With that precise point in mind it was easier to see and hear the signal fall-off when the coil was shifted. However, I agree that by not retuning the receiver after each shift it becomes a moot point.
Despite the flaws in the method, it still remains that I'm seeing a greater than 20 dB improvement over the stock loopstick, and that's excellent. If performance increases further with a coil at the rod's exact center, that will be even better.
I'm knee-deep in finalizing Wellbrook arrays and QDFA phased array antennas plus other preparations for a coastal DXpedition later this month, so I won't be able to return to ULR radio experimentation for a while. However, I'm sure Gary and others will be able to follow up on your and Scott's suggestions soon. I look forward to reading about these experiments of others.
73,
Guy Atkins
Puyallup, WA USA
On Tue, Feb 2, 2010 at 2:13 AM, <ultralightdx@...> wrote:
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Hello Roy and Guy,
Thanks for your comments in this discussion, and thanks once again to Guy
for his independent testing of my PL-380 7.5" loopstick design (and strong
confirmation of the great AM sensitivity boost obtained with it, an aspect
which seems to be overlooked in this marathon discussion, although it is the
primary objective of the vast majority of our group).
Roy, your comments and suggestions are appreciated, as well as those form
Scott. All of them will be tried here as time allows, since maximum loopstick
performance is presumably our common objective, and all ideas are
useful in this creative process.
Before delving into technical matters, however, there is one important
point which I hope all of the group can understand and appreciate. Both Guy and
I have used this PL-380 7.5" loopstick design to create an antenna which
has already been extensively tested against the "champion" design of modified
Ultralights-- the Eton E100 7.5" Slider model. This E100 Slider model has
already proven highly successful as a stand-alone receiver in multiple
DXpeditions, including Guy's vacation to Oregon last summer, Dr. Walt
Salmaniw's travels in the South Pacific recently, and my multiple Grayland
DXpeditions. After our optimal-sensitivity testing session on Saturday, Guy
and I both conducted a "Shootout" between the same E100 Slider model he used in
his Oregon DXpedition, and one of my new proof-tested PL-380 7.5" loopstick
models. We checked stations across the MW spectrum, and we both found that
the new PL-380 7.5" loopstick model could equal the performance of the E100
Slider in both selectivity AND sensitivity, without any need to tune a
Slider coil. This is a tremendous improvement in transoceanic DXing convenience,
especially during brief band openings (when time is critical). As such,
since Guy and I have already been successful in making these new
loopsticks with such impressive DXing performance, from our standpoint
(as DXers, not software engineers) a great degree of success has certainly
already been achieved.
(Roy's comments pasted below)
"Looking at the video of the coil being moved indicates that the all that is happening is that you are moving the coil away from a peak that has already been established from a previous tuning operation that has set the varactors capacitance to tune the loopstick at the black mark for the coils inductance at that position on the rod. It appears to me that the coil was originally tuned at the black mark then moved off peak before the video started. You cannot expect the Si4734 to track while moving the coil because it does not know the coil has moved and keeps the capacitance unchanged, but you have changed the inductance by moving the coil and of course the signal will rises and fall when you move the loopstick. Had the radio been retuned each time the coil was moved the Si4734 would have returned its varactor capacitance for the new inductance brought about by the movement and really the signal would not have changed by much more than about 3dbu across the rod" (my comments) Roy, I have run some further tests on the last remaining PL-380 7.5" test setup here, and you are correct on this point. Retuning the PL-380 (and starting with a new frequency each time the Slider coil is changed) is essential to understanding the Si4734 tuning operation, and how the varactor will compensate for frequency changes. As such, I think everyone is now much closer to agreement on how to optimize AM sensitivity in the final loopstick. Following your suggestion, however, some interesting test results were obtained. As both you and Guy have noticed, the 554 uh coil inductance does not typically provide as great a sensitivity boost on the upper frequencies (X-band) as on the lower frequencies. I set a Slider coil inductance of around 450 uh to investigate this, then retuned the PL-380 to 1680 kHz. In the 1680 kHz position, the 450 uh inductance did provide significantly higher average RSSI and S/N readings (relative to a stock unit) than did the 554 uh inductance, but the average RSSI and S/N readings at the 530 kHz frequency were then significantly reduced. It was almost as if the greater signal boost obtained at the 450 uh inductance on 1680 kHz was gained at the loss of some signal boost at the 530 kHz frequency. As we proceed to test the operation of the PL-380 at varying coil inductances, it certainly seems that in the case of the 40/44 Litz wire Slider coil on the type 61 Amidon ferrite bar, some compromise in the final inductance will be necessary to equalize the sensitivity boost throughout the AM band. Once such a "compromise inductance" is found, it would presumably be an easy matter to wind a coil of such inductance value in the center of the ferrite bar (as Scott suggests), and test whether this coil orientation would provide AM sensitivity superior to that of other coil locations. In any case, thanks again for your helpful suggestions , and especially for the continual atmosphere of discussing technical differences with mutual courtesy and respect. 73 , Gary DeBock (in Puyallup, WA, USA)
In a message dated 2/2/2010 1:37:00 P.M. Pacific Standard Time, roy.dyball@... writes:
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Roy <roy.dyball@...>
Hi Guy I noticed in your test that you had your radio tuned right at the bottom of the band (530Khz). I agree that with the same 81 turn sliding coil connected to my PL-380 that it showed an increase of about 20dbu and more importantly that the S/N had risen by some times up to 10-12db on the low frequency end of the band. These results are undeniable and improve the radio greatly Did you get a chance to try stations at the top of the band? My coil started to drop off above 1200Khz and at the top of the band showed an increase in dbu of only about 7-10 and no increase in S/N level. I also concur that my best results have been with coils wound in the centre of the rod. Extensive testing with different coils wound at the centre of the rod and different wire size and inductance has shown me that a value of inductance in the range 0f 330-350µH works the best over the entire band. I found that a coil of 70 turn (110mm) 660 Litz wire wound at the centre performed the best overall and had the least amount of noise. When the varactor values are read from the Si4734 chip with it tuned to 1710 Khz it reports a value of around 10pf indicating the chip has not run out of capacitance at the top of the band. The inductance could be increased if you dont want to work the top end of the band. The Welbrook range of gear looks like good gear and I hope your DX expedition goes well. Cheers Roy. --- In ultralightdx@..., Guy Atkins wrote:
> > Hi Roy, > > I really appreciate the clear fashion in which you (and Scott) explain the > SiLabs chip's operation! You are correct; I did not realize that the chip > tunes for proper inductance after it detects a change of frequency; I > thought it "senses" the inductance continuously, and displays any signal > strength changes during the "refresh" cycle of the RSSI indicator. > > I'd forgotten about the maxim of best "Q" with a centered coil. After so > many years of seeing stock loopsticks with factory coils positioned so far > from center, I've not given it much thought. I like Scott's idea of starting > coil winding right at the center, and seeing if there's any difference > between a 330 uH and 550 uH coil. > > The purpose of the black arrow marker in my video was simply to show the > positioning of the coil for which I had previously found to give the best > reception. With that precise point in mind it was easier to see and hear the > signal fall-off when the coil was shifted. However, I agree that by not > retuning the receiver after each shift it becomes a moot point. > > Despite the flaws in the method, it still remains that I'm seeing a greater > than 20 dB improvement over the stock loopstick, and that's excellent. If > performance increases further with a coil at the rod's exact center, that > will be even better. > > I'm knee-deep in finalizing Wellbrook arrays and QDFA phased array > antennas plus other preparations for a coastal DXpedition later this month, > so I won't be able to return to ULR radio experimentation for a while. > However, I'm sure Gary and others will be able to follow up on your and > Scott's suggestions soon. I look forward to reading about these experiments > of others. > > 73, > > Guy Atkins > Puyallup, WA USA > http://fivebelow.squarespace.com > > > > On Tue, Feb 2, 2010 at 2:13 AM, ultralightdx@... wrote: > > > Ultralight DX > > > > > > > > > > 13e. Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick > > Posted > > by: "Roy" roy.dyball@... > > roy.dyball@...?Subject=+Re%3A%20Guy%20Atkin%27s%20Independent%20Testing%20of%20PL-380%207%2E5%22%20Loopstick> > > roy.dyball <http://profiles.yahoo.com/roy.dyball> Tue Feb 2, 2010 12:56 am > > (PST) > > > > > > > > Hi Garry > > > > Looking at the video of the coil being moved indicates that the all that > > is happening is that you are moving the coil away from a peak that has > > already been established from a previous tuning operation that has set > > the varactors capacitance to tune the loopstick at the black mark for > > the coils inductance at that position on the rod. It appears to me that > > the coil was originally tuned at the black mark then moved off peak > > before the video started. > > > > You cannot expect the Si4734 to track while moving the coil because it > > does not know the coil has moved and keeps the capacitance unchanged, > > but you have changed the inductance by moving the coil and of course the > > signal will rises and fall when you move the loopstick. > > > > Had the radio been retuned each time the coil was moved the Si4734 would > > have returned its varactor capacitance for the new inductance brought > > about by the movement and really the signal would not have changed by > > much more than about 3dbu across the rod. > > > > The only time the Si4734 changes its capacitance to match the loopsticks > > inductance is during a tuning operation and this was not done in the > > video. The capacitance does not change automatically when you slide the > > coil. The whole idea of the Si4734 is it is self aligning. And that is > > why you must step off and step back on frequency every time you move the > > loopstick. > > > > It would be very interesting to see the video redone showing the method > > described above because every time the coil was moved and the frequency > > retuned the audio and the signal levels (within about 3dbu) would have > > come back up. > > > > We must understand how this chip works and use this chip as it is > > designed and not copy old methods from completely different technology > > without applying them to this new technology correctly. > > > > I think there has been a misunderstanding as to the correct operation of > > how the Si4734 works and I now that criticism can be taken the wrong way > > especially when someone has put a lot of work into their results and > > presented them sincerely. > > > > I really believe that the video showing a peak signal on the rod is > > incorrectly presented and had the radio been retuned between movements > > it would have only shown how cleaver the Si4734 really is at realigning > > itself and not a signal dropping off from an established peak. > > > > Cheers Roy. > > > > Create New Topic > > | > > Visit Your Group on the Web > > Messages<http://groups.yahoo.com/group/ultralightdx/messages;_ylc=X3oDMTJmN24zcDRyBF9TAzk3MzU5NzE1BGdycElkAzIxNjE0MDc2BGdycHNwSWQDMTcwNjA1ODAzNwRzZWMDZnRyBHNsawNtc2dzBHN0aW1lAzEyNjUxMDU2MTA->| > > Files| > > Photos| > > Links| > > Database| > > Polls<http://groups.yahoo.com/group/ultralightdx/polls;_ylc=X3oDMTJnajk3b21oBF9TAzk3MzU5NzE1BGdycElkAzIxNjE0MDc2BGdycHNwSWQDMTcwNjA1ODAzNwRzZWMDZnRyBHNsawNwb2xscwRzdGltZQMxMjY1MTA1NjEw>| > > Members| > > Calendar > > MARKETPLACE > > > > Going Green: Your Yahoo! Groups resource for green living > > [image: Yahoo! Groups]<http://groups.yahoo.com/;_ylc=X3oDMTJlMzF0MDgzBF9TAzk3MzU5NzE1BGdycElkAzIxNjE0MDc2BGdycHNwSWQDMTcwNjA1ODAzNwRzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTI2NTEwNTYxMA--> > > Change settings via the Web(Yahoo! ID required) > > Change settings via email: Switch delivery to Individualultralightdx-normal@...?subject=Email+Delivery:+Indiviual+Email>| Switch > > format to Traditionalultralightdx-traditional@...?subject=Change+Delivery+Format:+Traditional> > > Visit Your Group > > | > > Yahoo! Groups Terms of Use | Unsubscribe > > ultralightdx-unsubscribe@...?subject=Unsubscribe> > > > |
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Hi Roy,
Yes, I checked mid and high band signals too, and observed the average reading over one minute. Any frequency I tried showed improvement with the coil at the same approx. position from the end of the rod (about 1-5/8", where inductance was 532 or so). As you mentioned, the improvement is not as great when you tune up in frequency.
I made the video with 530 kHz, because there are steady, weak TIS stations audible on 530 from my location. I suppose I could have shown the effect in the video with other frequencies besides low band.
Thanks for the tip on the high strand count 660 Litz. When I made an E100 slider a couple summers ago, I used 172/44 Litz, but have never tried any variety approaching 660 strands. Do you feel that the number of strands affects the noise level, or does it have to do with the coil wound in the middle?
73,
Guy Atkins
Puyallup, WA USA
http://fivebelow.squarespace.com
toggle quoted message
Show quoted text
--- In ultralightdx@..., "Roy" wrote:
> > > Hi Guy > > I noticed in your test that you had your radio tuned right at the bottom > of the band (530Khz). > > I agree that with the same 81 turn sliding coil connected to my PL-380 > that it showed an increase of about 20dbu and more importantly that the > S/N had risen by some times up to 10-12db on the low frequency end of > the band. These results are undeniable and improve the radio greatly > > Did you get a chance to try stations at the top of the band? My coil > started to drop off above 1200Khz and at the top of the band showed an > increase in dbu of only about 7-10 and no increase in S/N level. > > I also concur that my best results have been with coils wound in the > centre of the rod. Extensive testing with different coils wound at the > centre of the rod and different wire size and inductance has shown me > that a value of inductance in the range 0f 330-350µH works the best > over the entire band. > > I found that a coil of 70 turn (110mm) 660 Litz wire wound at the centre > performed the best overall and had the least amount of noise. When the > varactor values are read from the Si4734 chip with it tuned to 1710 Khz > it reports a value of around 10pf indicating the chip has not run out of > capacitance at the top of the band. The inductance could be increased if > you dont want to work the top end of the band. > > The Welbrook range of gear looks like good gear and I hope your DX > expedition goes well. > > Cheers Roy. |
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Hi Scott and Roy,
Thanks for your comments, especially those concerning our ULR group
tradition of courtesy, and mutual respect.
Although our group has grown rapidly to over 500 members (with somewhat
divergent interests), it has been one tradition that we have tried to
maintain at all costs. It's always much more pleasant to work toward a
common goal, rather than a common row :-)
I'm sure that Guy and I will enjoy working together with you in
trying different combinations of coils and Litz wire, to see if we can squeeze
any more AM sensitivity out of the 7.5" PL-380 loopstick design. It appears that
7.5" PL-380 loopsticks could be designed to favor either the low band, high
band, or even the LW band. Ironically, this was the same situation that led
John, Guy and I to develop the E100 Slider models two years ago. Rather than
kick off another controversy, I'll keep quiet about weird plans to test out a
PL-380 7.5" Slider model to allow the optimization of all three band segments in
one PL-380 hotrod model :-)
73, Gary
In a message dated 2/2/2010 6:49:15 P.M. Pacific Standard Time,
sdwillingham@... writes:
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Roy <roy.dyball@...>
Guy When I ordered My Amidon rods 4,6,7.5" rods I also ordered 40/46, 165/46 and 630/46 (my mistake it is not 660) wire. I set about winding coils on all of the rods with different wire. After reading Ben Tongue article I was connived that the centre of the rod was the best part to wind the coil. Also knowing the Si4734 just adapted to the coil as long as it was in the inductance range specified in the chips notes this reinforced my belief to wind my coils in the centre to have the best Q. Every time I moved up a rod or a wire size the results got better. I did not use the 630 strand Litz on the 4 or 6" rod as there is not enough room. Just like if you built a bigger aeroplane with a longer fuselage you would not use the wings from a smaller aeroplane to lift it, so it seemed to me to be the same that the wire size should be increased with rod size. The DC resistance of the 630 Litz coil is so low that I can't read it. The same resistance associated with the same inductance of a 40/46 coil is a few ohms. So this must improve the Q for a start. My theory is that the larger wire size enables more of the rod to be covered by the coil thus enhancing the magnetic couple I don't know if it is specifically the Litz but maybe it is just the wire size, but I really would not consider using any other wire than Litz at that diameter. I have been using the 630 Litz coil now for many days listening to distant overland stations as the sun comes up. I just rewound the 81 turn 40/46 coil slider coil to test it again. The 630 Litz coil when judged from a listening point of view reminds me of my Sony 7600GR with a good low noise floor with the signal coming out of and returning to the noise floor gently, plus the soft mute did not seem to bug me as much. On the other hand the 40/46 coil seemed to pick up more hash from the radios display creating a buzz noticeable at some frequencies along with the polling request for the RSSI and S/N indicators. I advise all members to experiment for themselves with a bit of wire and some rods. That's what the fun of ULDXing is and I hope we can all calmly disuses our results. This points out that for the purest; at least two separate loopstick coils should be at hand. One for the top of the band and one for the bottom of the band. Cheers Roy.
--- In ultralightdx@..., "thinkdx" wrote:
> > Hi Roy, Yes, I checked mid and high band signals too, and observed the > average reading over one minute. Any frequency I tried showed > improvement with the coil at the same approx. position from the end of > the rod (about 1-5/8", where inductance was 532 or so). As you > mentioned, the improvement is not as great when you tune up in > frequency. I made the video with 530 kHz, because there are steady, > weak TIS stations audible on 530 from my location. I suppose I could > have shown the effect in the video with other frequencies besides low > band. Thanks for the tip on the high strand count 660 Litz. When I made > an E100 slider a couple summers ago, I used 172/44 Litz, but have never > tried any variety approaching 660 strands. Do you feel that the number > of strands affects the noise level, or does it have to do with the coil > wound in the middle? 73, Guy Atkins Puyallup, WA USA > http://fivebelow.squarespace.com > > --- In ultralightdx@..., "Roy" roy.dyball@ wrote: > > > > > > Hi Guy > > > > I noticed in your test that you had your radio tuned right at the > bottom > > of the band (530Khz). > > > > I agree that with the same 81 turn sliding coil connected to my > PL-380 > > that it showed an increase of about 20dbu and more importantly that > the > > S/N had risen by some times up to 10-12db on the low frequency end of > > the band. These results are undeniable and improve the radio greatly > > > > Did you get a chance to try stations at the top of the band? My coil > > started to drop off above 1200Khz and at the top of the band showed an > > increase in dbu of only about 7-10 and no increase in S/N level. > > > > I also concur that my best results have been with coils wound in the > > centre of the rod. Extensive testing with different coils wound at the > > centre of the rod and different wire size and inductance has shown me > > that a value of inductance in the range 0f 330-350µH works the best > > over the entire band. > > > > I found that a coil of 70 turn (110mm) 660 Litz wire wound at the > centre > > performed the best overall and had the least amount of noise. When the > > varactor values are read from the Si4734 chip with it tuned to 1710 > Khz > > it reports a value of around 10pf indicating the chip has not run out > of > > capacitance at the top of the band. The inductance could be increased > if > > you dont want to work the top end of the band. > > > > The Welbrook range of gear looks like good gear and I hope your DX > > expedition goes well. > > > > Cheers Roy. > |
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Roy <roy.dyball@...>
Hi Gary You have hit the nail right on the head. It is very hard to wind a loopstick that will perform well across the whole band. The Tecsun factory was not silly when they chose values of 220 µH for the PL-380 and 267 µH for the PL-310, winding their coils at the centre of the rod and thus producing a reasonably flat response across the band. However as you have found out they gave up response at the low end of the band to accomplish this by using lower values of inductance. As Scott pointed out adjusting your coil to lower the inductance by sliding it closer to the end will not give you true results and will confound your logic. As you are a seasoned coil winder you could wind several coils in a morning on the centre of the rod and test them I still have an open mind as to whether a coil former is necessary. I strongly suggest you try some larger Litz wire also so we can compare my results because I think it works better with the larger wire and it is worth trying. I don't think it is possible to have one coil perform as well across the band as two separate coils tailored for high and low frequencies. All of life is a compromise and Loopstick coils are no exception. I am really looking forward to your future results and hope we can all share our work with mutual respect. Roy. --- In ultralightdx@..., D1028Gary@... wrote:
> > Hello Roy and Guy, > > Thanks for your comments in this discussion, and thanks once again to Guy > for his independent testing of my PL-380 7.5" loopstick design (and strong > confirmation of the great AM sensitivity boost obtained with it, an aspect > which seems to be overlooked in this marathon discussion, although it is the > primary objective of the vast majority of our group). > > Roy, your comments and suggestions are appreciated, as well as those form > Scott. All of them will be tried here as time allows, since maximum > loopstick performance is presumably our common objective, and all ideas are useful > in this creative process. > > Before delving into technical matters, however, there is one important > point which I hope all of the group can understand and appreciate. Both Guy and > I have used this PL-380 7.5" loopstick design to create an antenna which > has already been extensively tested against the "champion" design of > modified Ultralights-- the Eton E100 7.5" Slider model. This E100 Slider model has > already proven highly successful as a stand-alone receiver in multiple > DXpeditions, including Guy's vacation to Oregon last summer, Dr. Walt > Salmaniw's travels in the South Pacific recently, and my multiple Grayland > DXpeditions. After our optimal-sensitivity testing session on Saturday, Guy and I > both conducted a "Shootout" between the same E100 Slider model he used in > his Oregon DXpedition, and one of my new proof-tested PL-380 7.5" loopstick > models. We checked stations across the MW spectrum, and we both found that > the new PL-380 7.5" loopstick model could equal the performance of the E100 > Slider in both selectivity AND sensitivity, without any need to tune a > Slider coil. This is a tremendous improvement in transoceanic DXing > convenience, especially during brief band openings (when time is critical). As such, > since Guy and I have already been successful in making these new loopsticks > with such impressive DXing performance, from our standpoint (as DXers, not > software engineers) a great degree of success has certainly already been > achieved. > > (Roy's comments pasted below) > > "Looking at the video of the coil being moved indicates that the all that > is happening is that you are moving the coil away from a peak that has > already been established from a previous tuning operation that has set the > varactors capacitance to tune the loopstick at the black mark for the coils > inductance at that position on the rod. It appears to me that the coil was > originally tuned at the black mark then moved off peak before the video > started. > You cannot expect the Si4734 to track while moving the coil because it > does not know the coil has moved and keeps the capacitance unchanged, but you > have changed the inductance by moving the coil and of course the signal > will rises and fall when you move the loopstick. > Had the radio been retuned each time the coil was moved the Si4734 would > have returned its varactor capacitance for the new inductance brought about > by the movement and really the signal would not have changed by much more > than about 3dbu across the rod" > (my comments) > Roy, I have run some further tests on the last remaining PL-380 7.5" test > setup here, and you are correct on this point. Retuning the PL-380 (and > starting with a new frequency each time the Slider coil is changed) is > essential to understanding the Si4734 tuning operation, and how the varactor > will compensate for frequency changes. As such, I think everyone is now much > closer to agreement on how to optimize AM sensitivity in the final > loopstick. > Following your suggestion, however, some interesting test results were > obtained. As both you and Guy have noticed, the 554 uh coil inductance does > not typically provide as great a sensitivity boost on the upper frequencies > (X-band) as on the lower frequencies. I set a Slider coil inductance of > around 450 uh to investigate this, then retuned the PL-380 to 1680 kHz. In the > 1680 kHz position, the 450 uh inductance did provide significantly higher > average RSSI and S/N readings (relative to a stock unit) than did the 554 > uh inductance, but the average RSSI and S/N readings at the 530 kHz > frequency were then significantly reduced. It was almost as if the greater signal > boost obtained at the 450 uh inductance on 1680 kHz was gained at the loss > of some signal boost at the 530 kHz frequency. As we proceed to test the > operation of the PL-380 at varying coil inductances, it certainly seems that > in the case of the 40/44 Litz wire Slider coil on the type 61 Amidon > ferrite bar, some compromise in the final inductance will be necessary to > equalize the sensitivity boost throughout the AM band. Once such a "compromise > inductance" is found, it would presumably be an easy matter to wind a coil of > such inductance value in the center of the ferrite bar (as Scott > suggests), and test whether this coil orientation would provide AM sensitivity > superior to that of other coil locations. > In any case, thanks again for your helpful suggestions , and especially > for the continual atmosphere of discussing technical differences with mutual > courtesy and respect. > 73 , Gary DeBock (in Puyallup, WA, USA) > In a message dated 2/2/2010 1:37:00 P.M. Pacific Standard Time, > roy.dyball@... writes: > > > > > Hi Guy > I noticed in your test that you had your radio tuned right at the bottom > of the band (530Khz). > I agree that with the same 81 turn sliding coil connected to my PL-380 > that it showed an increase of about 20dbu and more importantly that the S/N > had risen by some times up to 10-12db on the low frequency end of the band. > These results are undeniable and improve the radio greatly > Did you get a chance to try stations at the top of the band? My coil > started to drop off above 1200Khz and at the top of the band showed an increase > in dbu of only about 7-10 and no increase in S/N level. > I also concur that my best results have been with coils wound in the > centre of the rod. Extensive testing with different coils wound at the centre of > the rod and different wire size and inductance has shown me that a value > of inductance in the range 0f 330-350µH works the best over the entire band. > > I found that a coil of 70 turn (110mm) 660 Litz wire wound at the centre > performed the best overall and had the least amount of noise. When the > varactor values are read from the Si4734 chip with it tuned to 1710 Khz it > reports a value of around 10pf indicating the chip has not run out of > capacitance at the top of the band. The inductance could be increased if you dont > want to work the top end of the band. > The Welbrook range of gear looks like good gear and I hope your DX > expedition goes well. > Cheers Roy. > --- In ultralightdx@ In u--- In ultradx@ wrote: > > > > Hi Roy, > > > > I really appreciate the clear fashion in which you (and Scott) explain > the > > SiLabs chip's operation! You are correct; I did not realize that the chip > > tunes for proper inductance after it detects a change of frequency; I > > thought it "senses" the inductance continuously, and displays any signal > > strength changes during the "refresh" cycle of the RSSI indicator. > > > > I'd forgotten about the maxim of best "Q" with a centered coil. After so > > many years of seeing stock loopsticks with factory coils positioned so > far > > from center, I've not given it much thought. I like Scott's idea of > starting > > coil winding right at the center, and seeing if there's any difference > > between a 330 uH and 550 uH coil. > > > > The purpose of the black arrow marker in my video was simply to show the > > positioning of the coil for which I had previously found to give the > best > > reception. With that precise point in mind it was easier to see and hear > the > > signal fall-off when the coil was shifted. However, I agree that by not > > retuning the receiver after each shift it becomes a moot point. > > > > Despite the flaws in the method, it still remains that I'm seeing a > greater > > than 20 dB improvement over the stock loopstick, and that's excellent. If > > performance increases further with a coil at the rod's exact center, that > > will be even better. > > > > I'm knee-deep in finalizing Wellbrook arrays and QDFA phased array > > antennas plus other preparations for a coastal DXpedition later this > month, > > so I won't be able to return to ULR radio experimentation for a while. > > However, I'm sure Gary and others will be able to follow up on your and > > Scott's suggestions soon. I look forward to reading about these > experiments > > of others. > > > > 73, > > > > Guy Atkins > > Puyallup, WA USA > > http://fivebelow. http:// > > > > > > > > On Tue, Feb 2, 2010 at 2:13 AM, ultralightdx@ On Tue, On Tue, F > > > > > Ultralight DX > > > > > ups. > > > > > > > > > > > > > 13e. Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick > > > > > ttp://groups. Posted > > > by: "Roy" roy.dyball@ b > > > roy.dyball@ roy.dy roy.dyba roy.dyb roy.dybal roy.d roy.d > roy.dyb roy.dybal> > > > roy.dyball Tue Feb 2, 2010 > 12:56 am > > > (PST) > > > > > > > > > > > > Hi Garry > > > > > > Looking at the video of the coil being moved indicates that the all > that > > > is happening is that you are moving the coil away from a peak that has > > > already been established from a previous tuning operation that has set > > > the varactors capacitance to tune the loopstick at the black mark for > > > the coils inductance at that position on the rod. It appears to me > that > > > the coil was originally tuned at the black mark then moved off peak > > > before the video started. > > > > > > You cannot expect the Si4734 to track while moving the coil because it > > > does not know the coil has moved and keeps the capacitance unchanged, > > > but you have changed the inductance by moving the coil and of course > the > > > signal will rises and fall when you move the loopstick. > > > > > > Had the radio been retuned each time the coil was moved the Si4734 > would > > > have returned its varactor capacitance for the new inductance brought > > > about by the movement and really the signal would not have changed by > > > much more than about 3dbu across the rod. > > > > > > The only time the Si4734 changes its capacitance to match the > loopsticks > > > inductance is during a tuning operation and this was not done in the > > > video. The capacitance does not change automatically when you slide the > > > coil. The whole idea of the Si4734 is it is self aligning. And that is > > > why you must step off and step back on frequency every time you move > the > > > loopstick. > > > > > > It would be very interesting to see the video redone showing the method > > > described above because every time the coil was moved and the frequency > > > retuned the audio and the signal levels (within about 3dbu) would have > > > come back up. > > > > > > We must understand how this chip works and use this chip as it is > > > designed and not copy old methods from completely different technology > > > without applying them to this new technology correctly. > > > > > > I think there has been a misunderstanding as to the correct operation > of > > > how the Si4734 works and I now that criticism can be taken the wrong > way > > > especially when someone has put a lot of work into their results and > > > presented them sincerely. > > > > > > I really believe that the video showing a peak signal on the rod is > > > incorrectly presented and had the radio been retuned between movements > > > it would have only shown how cleaver the Si4734 really is at > realigning > > > itself and not a signal dropping off from an established peak. > > > > > > Cheers Roy. > > > > > > Create New Topic > > > > > ttp://grHN0aW1lHN0aW1l > > > Visit Your Group on the > Web> > > > > Messages> //groups.> > > > Files> ps.| > > > > Photos> oups.| > > > > Links> ps.| > > > > Database> //groups.| > > > > Polls> ps.| > > > > Members> groups.| > > > > Calendar> //groups. > > > MARKETPLACE > > > > > > Going Green: Your Yahoo! Groups resource for green > living> //us.ardhttp://us.ardhttp://us.ard.http://us.ard.> .ard.> http://us.http:/> > > > [image: Yahoo! > Groups]> p://groups. > > > Change settings via the > Web> //groups.(Yahoo! ID > required) > > > Change settings via email: Switch delivery to Individualultraligh > Change set Change sett Change sett Change setting Change set Chan>| Switch > > > format to Traditionalultralig format to T format to format to > format to T format to T fo> > > > Visit Your Group > > > > > ups.| > > > Yahoo! Groups Terms of Use | > Unsubscribe > > > ultralightdx- ultrali ultrali ultrali ultral> > > > > > > |
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neil.findlay52
Roy and other folk in the group
I hope my plug-in rod idea works -- so I can try your idea
But i saw some other rods -- not sure if we can get them in Australia
My son seels we not be able to due to a technology ban as the could be used to track submarines on VLF
On the site it says US only no international orders
see the monster rod section - the say they are mu 125 which seems to be what type 61 is
Up to 27inch long and 1inch diameter - there are some medium wave radios using the smaller ones on the site
though much of the site deals with ELF and VLF
Has anyone tried using these rods & or would they be useful at MW compared to the Amidon's
Regards
Neil
From: Roy To: ultralightdx@... Sent: Wed, 3 February, 2010 11:50:37 AM Subject: [ultralightdx] Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick
Guy When I ordered My Amidon rods 4,6,7.5" rods I also ordered 40/46, 165/46 and 630/46 (my mistake it is not 660) wire. I set about winding coils on all of the rods with different wire. After reading Ben Tongue article I was connived that the centre of the rod was the best part to wind the coil. Also knowing the Si4734 just adapted to the coil as long as it was in the inductance range specified in the chips notes this reinforced my belief to wind my coils in the centre to have the best Q. Every time I moved up a rod or a wire size the results got better. I did not use the 630 strand Litz on the 4 or 6" rod as there is not enough room. Just like if you built a bigger aeroplane with a longer fuselage you would not use the wings from a smaller aeroplane to lift it, so it seemed to me to be the same that the wire size should be increased with rod size. The DC resistance of the 630 Litz coil is so low that I can't read it. The same resistance associated with the same inductance of a 40/46 coil is a few ohms. So this must improve the Q for a start. My theory is that the larger wire size enables more of the rod to be covered by the coil thus enhancing the magnetic couple I don't know if it is specifically the Litz but maybe it is just the wire size, but I really would not consider using any other wire than Litz at that diameter. I have been using the 630 Litz coil now for many days listening to distant overland stations as the sun comes up. I just rewound the 81 turn 40/46 coil slider coil to test it again. The 630 Litz coil when judged from a listening point of view reminds me of my Sony 7600GR with a good low noise floor with the signal coming out of and returning to the noise floor gently, plus the soft mute did not seem to bug me as much. On the other hand the 40/46 coil seemed to pick up more hash from the radios display creating a buzz noticeable at some frequencies along with the polling request for the RSSI and S/N indicators. I advise all members to experiment for themselves with a bit of wire and some rods. That's what the fun of ULDXing is and I hope we can all calmly disuses our results. This points out that for the purest; at least two separate loopstick coils should be at hand. One for the top of the band and one for the bottom of the band. Cheers Roy.
--- In ultralightdx@ yahoogroups. com, "thinkdx" wrote: Yahoo!7: Catch-up on your favourite Channel 7 TV shows easily, legally, and for free at PLUS7. Check it out. |
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sdwillingham
To All,
toggle quoted message
Show quoted text
I'd like to reinforce Gary's sentiment here. Since joining this group, I've found everyone to be helpful in pursuing common goals. And mutual respect can keep the group on-track and useful. I'll make a little confession. When I first watched Guy's video, I started to type up an impatient response about how it was done all wrong, etc. Then I thought better of it. The Si4734 does many things entirely different from past designs, and it's foolish to expect that one or two explanations will reach everyone (or even be clear for that matter). So I wrote a new post, concentrating on just one misunderstanding that I felt I could clarify. Roy later responded with his thorough and patient post. The resulting thread is far better than it might have been. Cheers and Respect, Scott --- In ultralightdx@..., D1028Gary@... wrote:
In any case, thanks again for your helpful suggestions , and especially |
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Roy <roy.dyball@...>
Neil They are some big rods. I think it's like the old saying that "there is no substitute for CCs" when it comes to the power output of an auto engine, I think it is the same for ferrite as long as your coil couples to it. You would have to try one and find out maybe other members have. The pre wound MW coils on the small rods are the same as I bought from Dick Smith Electronics for $1.50 each and are the same inductance. They also have the message on the variable capacitor page about no overseas orders so it is probable they just don't want to ship overseas. Cheers Roy.
--- In ultralightdx@..., Neil Findlay wrote: > > Roy and other folk in the group > > I hope my plug-in rod idea works -- so I can try your idea > > But i saw some other rods -- not sure if we can get them in Australia > My son seels we not be able to due to a technology ban as the could be used to track submarines on VLF > On the site it says US only no international orders > > Site is http://www.stormwise.com/index.html > > see the monster rod section - the say they are mu 125 which seems to be what type 61 is > Up to 27inch long and 1inch diameter - there are some medium wave radios using the smaller ones on the site > though much of the site deals with ELF and VLF > > Has anyone tried using these rods & or would they be useful at MW compared to the Amidon's > > Regards > Neil > > > > > ________________________________ > From: Roy roy.dyball@... > To: ultralightdx@... > Sent: Wed, 3 February, 2010 11:50:37 AM > Subject: [ultralightdx] Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick > >  > --- In ultralightdx@ yahoogroups. com, "thinkdx" dx@ wrote: > > > > Hi Roy, Yes, I checked mid and high band signals too, and observed the > > average reading over one minute. Any frequency I tried showed > > improvement with the coil at the same approx. position from the end of > > the rod (about 1-5/8", where inductance was 532 or so). As you > > mentioned, the improvement is not as great when you tune up in > > frequency. I made the video with 530 kHz, because there are steady, > > weak TIS stations audible on 530 from my location. I suppose I could > > have shown the effect in the video with other frequencies besides low > > band. Thanks for the tip on the high strand count 660 Litz. When I made > > an E100 slider a couple summers ago, I used 172/44 Litz, but have never > > tried any variety approaching 660 strands. Do you feel that the number > > of strands affects the noise level, or does it have to do with the coil > > wound in the middle? 73, Guy Atkins Puyallup, WA USA > > http://fivebelow. squarespace. com > > > > --- In ultralightdx@ yahoogroups. com, "Roy" roy.dyball@ wrote: > > > > > > > > > Hi Guy > > > > > > I noticed in your test that you had your radio tuned right at the > > bottom > > > of the band (530Khz). > > > > > > I agree that with the same 81 turn sliding coil connected to my > > PL-380 > > > that it showed an increase of about 20dbu and more importantly that > > the > > > S/N had risen by some times up to 10-12db on the low frequency end of > > > the band. These results are undeniable and improve the radio greatly > > > > > > Did you get a chance to try stations at the top of the band? My coil > > > started to drop off above 1200Khz and at the top of the band showed an > > > increase in dbu of only about 7-10 and no increase in S/N level. > > > > > > I also concur that my best results have been with coils wound in the > > > centre of the rod. Extensive testing with different coils wound at the > > > centre of the rod and different wire size and inductance has shown me > > > that a value of inductance in the range 0f 330-350µH works the best > > > over the entire band. > > > > > > I found that a coil of 70 turn (110mm) 660 Litz wire wound at the > > centre > > > performed the best overall and had the least amount of noise. When the > > > varactor values are read from the Si4734 chip with it tuned to 1710 > > Khz > > > it reports a value of around 10pf indicating the chip has not run out > > of > > > capacitance at the top of the band. The inductance could be increased > > if > > > you dont want to work the top end of the band. > > > > > > The Welbrook range of gear looks like good gear and I hope your DX > > > expedition goes well. > > > > > > Cheers Roy. > > > > Guy > When I ordered My Amidon rods 4,6,7.5" rods I also ordered 40/46, 165/46 and 630/46 (my mistake it is not 660) wire. I set about winding coils on all of the rods with different wire. After reading Ben Tongue article I was connived that the centre of the rod was the best part to wind the coil. Also knowing the Si4734 just adapted to the coil as long as it was in the inductance range specified in the chips notes this reinforced my belief to wind my coils in the centre to have the best Q. > Every time I moved up a rod or a wire size the results got better. I did not use the 630 strand Litz on the 4 or 6" rod as there is not enough room. Just like if you built a bigger aeroplane with a longer fuselage you would not use the wings from a smaller aeroplane to lift it, so it seemed to me to be the same that the wire size should be increased with rod size. > The DC resistance of the 630 Litz coil is so low that I can't read it. The same resistance associated with the same inductance of a 40/46 coil is a few ohms. So this must improve the Q for a start. My theory is that the larger wire size enables more of the rod to be covered by the coil thus enhancing the magnetic couple I don't know if it is specifically the Litz but maybe it is just the wire size, but I really would not consider using any other wire than Litz at that diameter. > I have been using the 630 Litz coil now for many days listening to distant overland stations as the sun comes up. I just rewound the 81 turn 40/46 coil slider coil to test it again. The 630 Litz coil when judged from a listening point of view reminds me of my Sony 7600GR with a good low noise floor with the signal coming out of and returning to the noise floor gently, plus the soft mute did not seem to bug me as much. On the other hand the 40/46 coil seemed to pick up more hash from the radios display creating a buzz noticeable at some frequencies along with the polling request for the RSSI and S/N indicators. I advise all members to experiment for themselves with a bit of wire and some rods. That's what the fun of ULDXing is and I hope we can all calmly disuses our results. > This points out that for the purest; at least two separate loopstick coils should be at hand. One for the top of the band and one for the bottom of the band. > Cheers Roy. >  > > > > __________________________________________________________________________________ > Yahoo!7: Catch-up on your favourite Channel 7 TV shows easily, legally, and for free at PLUS7. www.tv.yahoo.com.au/plus7 > |
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Pollock,Raphael E <rpollock@...>
I don't know about the Amidon, but I have the Stormwise 27" center wound with 660 Litz--a very potent combination that out performs my 3' air core homebrew as well as Crane twin ferrite and unamplified Select-a-tenna. From: ultralightdx@... <ultralightdx@...> To: ultralightdx@... <ultralightdx@...> Sent: Tue Feb 02 20:39:24 2010 Subject: Re: [ultralightdx] Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick Roy and other folk in the group
I hope my plug-in rod idea works -- so I can try your idea
But i saw some other rods -- not sure if we can get them in Australia
My son seels we not be able to due to a technology ban as the could be used to track submarines on VLF
On the site it says US only no international orders
see the monster rod section - the say they are mu 125 which seems to be what type 61 is
Up to 27inch long and 1inch diameter - there are some medium wave radios using the smaller ones on the site
though much of the site deals with ELF and VLF
Has anyone tried using these rods & or would they be useful at MW compared to the Amidon's
Regards
Neil
From: Roy <roy.dyball@yahoo. To: ultralightdx@ Sent: Wed, 3 February, 2010 11:50:37 AM Subject: [ultralightdx] Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick
Guy When I ordered My Amidon rods 4,6,7.5" rods I also ordered 40/46, 165/46 and 630/46 (my mistake it is not 660) wire. I set about winding coils on all of the rods with different wire. After reading Ben Tongue article I was connived that the centre of the rod was the best part to wind the coil. Also knowing the Si4734 just adapted to the coil as long as it was in the inductance range specified in the chips notes this reinforced my belief to wind my coils in the centre to have the best Q. Every time I moved up a rod or a wire size the results got better. I did not use the 630 strand Litz on the 4 or 6" rod as there is not enough room. Just like if you built a bigger aeroplane with a longer fuselage you would not use the wings from a smaller aeroplane to lift it, so it seemed to me to be the same that the wire size should be increased with rod size. The DC resistance of the 630 Litz coil is so low that I can't read it. The same resistance associated with the same inductance of a 40/46 coil is a few ohms. So this must improve the Q for a start. My theory is that the larger wire size enables more of the rod to be covered by the coil thus enhancing the magnetic couple I don't know if it is specifically the Litz but maybe it is just the wire size, but I really would not consider using any other wire than Litz at that diameter. I have been using the 630 Litz coil now for many days listening to distant overland stations as the sun comes up. I just rewound the 81 turn 40/46 coil slider coil to test it again. The 630 Litz coil when judged from a listening point of view reminds me of my Sony 7600GR with a good low noise floor with the signal coming out of and returning to the noise floor gently, plus the soft mute did not seem to bug me as much. On the other hand the 40/46 coil seemed to pick up more hash from the radios display creating a buzz noticeable at some frequencies along with the polling request for the RSSI and S/N indicators. I advise all members to experiment for themselves with a bit of wire and some rods. That's what the fun of ULDXing is and I hope we can all calmly disuses our results. This points out that for the purest; at least two separate loopstick coils should be at hand. One for the top of the band and one for the bottom of the band. Cheers Roy.
--- In ultralightdx@ yahoogroups. com, "thinkdx" <dx@...> wrote: Yahoo!7: Catch-up on your favourite Channel 7 TV shows easily, legally, and for free at PLUS7. Check it out. |
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sdwillingham
Gary,
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Using different inductances to optimize different band segments should not be controversial. In addition to a slider arrangement, other possibilities are those used by crystal-set enthusiasts: 1) A fixed coil with multiple taps. 2) Ben Tongue describes a simple arrangement with two equal coils on one ferrite rod. Putting the coils in series gives a large inductor optimized for the low end of the band. Putting the coils in parallel optimizes the high end of the band. He also tweaks the windings for higher Q, but I'm not sure our radios need that. While on the topic of sliders, I have an idea that I've wondered if you have tried. The idea is to "invert" your slider arrangement. Instead of a fixed ferrite and a sliding coil, how about a fixed coil with sliding ferrite rod? This could have a couple of advantages, mainly because you could completely slide the ferrite out of the coil form. Advantage 1 is that the coil without ferrite is attached to the radio and more compact for storage and transportation. Advantage 2 is that you can use one (somewhat expensive) ferrite rod for multiple radios (one at a time). Even when not taking advantage of the continuous sliding nature, this seems an efficient way to build a "fleet" of antennas. -Scott- --- In ultralightdx@..., D1028Gary@... wrote:
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Hi Scott, However, the sheer weight of the Stormwise rod turned out to be the modded E100's undoing. The parts I used just couldn't handle the mass and the friction was too great between the coil pieces and support. I tried a number of methods to reduce the friction but rescuing the project was a lost cause. It worked well before the antenna started falling apart under its own weight, though! My goal was to be able to accurately peak & adjust the "slider" and not have inductance change accidentally while DXing, should I bump or touch the coil (as can easily happen with the traditional sliding coil over the ferrite). I've uploaded some photos of this design to the Photos section of this Yahoogroup. Look for the album titled "E100 with Screw-feed Stormwise Rod". 73, Guy Atkins
--- In ultralightdx@..., "sdwillingham" wrote: > > > > > Gary, > > Using different inductances to optimize different band > segments should not be controversial. In addition to > a slider arrangement, other possibilities are those > used by crystal-set enthusiasts: > > 1) A fixed coil with multiple taps. > 2) Ben Tongue describes a simple arrangement with two > equal coils on one ferrite rod. Putting the coils in > series gives a large inductor optimized for the low > end of the band. Putting the coils in parallel > optimizes the high end of the band. He also tweaks > the windings for higher Q, but I'm not sure our radios > need that. > > While on the topic of sliders, I have an idea that I've > wondered if you have tried. The idea is to "invert" > your slider arrangement. Instead of a fixed ferrite and > a sliding coil, how about a fixed coil with sliding > ferrite rod? This could have a couple of advantages, > mainly because you could completely slide the ferrite > out of the coil form. Advantage 1 is that the coil without > ferrite is attached to the radio and more compact for > storage and transportation. Advantage 2 is that you can > use one (somewhat expensive) ferrite rod for multiple > radios (one at a time). Even when not taking advantage > of the continuous sliding nature, this seems an efficient > way to build a "fleet" of antennas. > > -Scott- |
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Pollock,Raphael E <rpollock@...>
I have a 27" Stormwise center wrapped w/ 38 turns of Litz 660 wire that feeds into a 365 pf variable capacitor. Sharp and high Q that consistently outperforms my 3' x 3' homebrew air core box loop.
I can use the ferrite bar antenna with either inductive or direct coupling (a secondary winding--four turns directly on top of the main winding, terminated into a 1/8" female). The antenna output can be fed into a small RF preamp (BAX-1) that have from many
years ago. The entire antenna is enclosed in some air conditioning foam insulation and placed into a 2" diameter PVC pipe--the varicap is at one end and the 1/8' female at the other. i have the antenna mounted on a camera tripod for full rotation and tilt
capabilities.
It might be neat to see if Stormwise would be able to fabricate longer and/or thicker ferrite bars--i am very happy with this antenna. i might mention that an article about monster ferrite bar antennas I found in
the Ultralight files section, John Bryant co-author, gave me much stimulus to build my contraption. It has much sharper Q than a glued together 24"er that i made from Amidon 7.5" bars a number of years ago. Happy to address any questions... From: ultralightdx@... [ultralightdx@...] On Behalf Of Neil Findlay [neil.findlay52@...] Sent: Tuesday, February 02, 2010 8:39 PM To: ultralightdx@... Subject: Re: [ultralightdx] Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick Roy and other folk in the group
I hope my plug-in rod idea works -- so I can try your idea
But i saw some other rods -- not sure if we can get them in Australia
My son seels we not be able to due to a technology ban as the could be used to track submarines on VLF
On the site it says US only no international orders
see the monster rod section - the say they are mu 125 which seems to be what type 61 is
Up to 27inch long and 1inch diameter - there are some medium wave radios using the smaller ones on the site
though much of the site deals with ELF and VLF
Has anyone tried using these rods & or would they be useful at MW compared to the Amidon's
Regards
Neil
From: Roy com> To: ultralightdx@ Sent: Wed, 3 February, 2010 11:50:37 AM Subject: [ultralightdx] Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick Guy When I ordered My Amidon rods 4,6,7.5" rods I also ordered 40/46, 165/46 and 630/46 (my mistake it is not 660) wire. I set about winding coils on all of the rods with different wire. After reading Ben Tongue article I was connived that the centre of the rod was the best part to wind the coil. Also knowing the Si4734 just adapted to the coil as long as it was in the inductance range specified in the chips notes this reinforced my belief to wind my coils in the centre to have the best Q. Every time I moved up a rod or a wire size the results got better. I did not use the 630 strand Litz on the 4 or 6" rod as there is not enough room. Just like if you built a bigger aeroplane with a longer fuselage you would not use the wings from a smaller aeroplane to lift it, so it seemed to me to be the same that the wire size should be increased with rod size. The DC resistance of the 630 Litz coil is so low that I can't read it. The same resistance associated with the same inductance of a 40/46 coil is a few ohms. So this must improve the Q for a start. My theory is that the larger wire size enables more of the rod to be covered by the coil thus enhancing the magnetic couple I don't know if it is specifically the Litz but maybe it is just the wire size, but I really would not consider using any other wire than Litz at that diameter. I have been using the 630 Litz coil now for many days listening to distant overland stations as the sun comes up. I just rewound the 81 turn 40/46 coil slider coil to test it again. The 630 Litz coil when judged from a listening point of view reminds me of my Sony 7600GR with a good low noise floor with the signal coming out of and returning to the noise floor gently, plus the soft mute did not seem to bug me as much. On the other hand the 40/46 coil seemed to pick up more hash from the radios display creating a buzz noticeable at some frequencies along with the polling request for the RSSI and S/N indicators. I advise all members to experiment for themselves with a bit of wire and some rods. That's what the fun of ULDXing is and I hope we can all calmly disuses our results. This points out that for the purest; at least two separate loopstick coils should be at hand. One for the top of the band and one for the bottom of the band. Cheers Roy.
--- In ultralightdx@ yahoogroups. com, "thinkdx" wrote: Yahoo!7: Catch-up on your favourite Channel 7 TV shows easily, legally, and for free at PLUS7. Check it out. |
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jim_kr1s <jkearman@...>
Ralph,
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Thanks for all the info. --- In ultralightdx@..., "Pollock,Raphael E" wrote: > > It might be neat to see if Stormwise would be able to fabricate longer and/or thicker ferrite bars--i am very happy with this antenna. i might mention that an article about monster ferrite bar antennas I found in the Ultralight files section, John Bryant co-author, gave me much stimulus to build my contraption. It has much sharper Q than a glued together 24"er that i made from Amidon 7.5" bars a number of years ago. Happy to address any questions... Ferrite rods are non-conductive, so gluing them together end-to-end should give results similar to a solid rod of the same length. There may be other variations between the mixtures used in the two samples. It would be worth trying two Stormwise rods glued together. Signal strengths might only increase 3 dB, but the null could be fantastic. Works I've cited in other posts indicate that rod thickness has little effect on inductance, and not a great effect on Q. You've probably gotten nearly as much Q as it's possible to obtain, just by using Litz wire. Q varies across the band depending on the gap between the winding and the core. See the Ben Tongue paper for more on this. Changing the LC ratio could work, too, but suitable capacitors are hard to find. In a regenerative receiver I paralleled three, 365-pF sections and added some fixed C, to reduce the LC ratio, which was desirable in this application. The MW band is so wide, it's hard to get one inductor to work optimally across it, in any application. You might experiment with different coils for high and low frequencies, or even use three. Not as handy for tuning up and down the band, but I think it would be worth trying. Of course, you reach a point where increased Q makes the antenna harder to tune because the peak is so narrow. I could live with that! If you really want to boost Q, try making a regenerative preamp in which the antenna is the tuned circuit. I believe Kiwa or Crane had one. Now you're looking at Qs in the tens of thousands! Even with some damping resistance my regen will clip the sidebands of an AM signal. I've coupled from its tank into a ULR, but mostly it's been more trouble than it was worth, given the inherent selectivity of the PL-380. The increase in gain is sometimes useful, though. 73, Jim, KR1S http://qrp.kearman.com/ |
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