Date
1 - 20 of 23
New antenna, new loggings
jim_kr1s <jkearman@...>
For the last few months I've been working on a new antenna for my PL-380. Now I have one that does just what I want, and it cost me less than $10.00. It's a 23-inch diameter, three-turn circular loop, matched to the radio through a 4:1 ferrite-toroid transformer. The transformer secondary replaces the internal antenna. This antenna requires no separate tuning adjustment; all tuning is done by the on-chip varactor. Does it work? You betcha! Signal strengths and nulling are exceptional. Now I just tune the radio to a frequency and swing the loop around for best reception or nulling. Last night and this morning it helped me add three new stations to my log.
This isn't a project for everyone. As built, it replaces the radio's internal antenna. Because there are bound to be differences in antenna construction, some tweaking of the impedance-matching transformer will improve performance. If you have the experience to perform this modification, all you need to know is here: http://kr1s.kearman.com/html/hooploop.html Write me off-list if you have questions. jkearman at att dot net
Here are the loggings. Times in UTC.
Current ULR total, 405 stations.
73,
Jim, KR1S
http://kr1s.kearman.com/
This isn't a project for everyone. As built, it replaces the radio's internal antenna. Because there are bound to be differences in antenna construction, some tweaking of the impedance-matching transformer will improve performance. If you have the experience to perform this modification, all you need to know is here: http://kr1s.kearman.com/html/hooploop.html Write me off-list if you have questions. jkearman at att dot net
Here are the loggings. Times in UTC.
| 03-16 | 2300 | 1150 | WGBR | Goldsboro | NC | Ad for crazywayno.com, ID 2310Z, Prime Time in the ACC |
| 2330 | 1580 | WCCF | Punta Gorda | FL | Talk, local ads Florida #139 |
|
| 03-17 | 0300 | 1250 | WTMA | Charleston | SC | Talk, CBS news |
| 1130 | 1160 | WTEL | Red Springs | NC | Church ann, ad Freedom Gospel Hour |
Current ULR total, 405 stations.
73,
Jim, KR1S
http://kr1s.kearman.com/
Tony Germanotta
Wow, that looks fantastic Jim. I am jealous. I think when I finally get some free time I am going to explore your version that allows you to use it barefoot as well as with the antenna.
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Do you notice any improvement over just inductively coupling the 380 with your outboard loop? Other than no need to twiddle the knob for a peak? It should null better with no internal antenna at play. But you lose the ability to carefully position the two antennas for some physical, rather than electronic, signal phasing to eliminate backside signals.
Have you considered a loop using a turn or two around an interior door? That would give you a really large capture area, and the door can be rotated through at least half of a compass which shouldn't be a problem if you pick the right door.
I wonder how well that loop would work with the PL-360. Would you even need the matching transformer?
And I've been meaning to echo the congratulations on your amazing DX success. At least you get an extra hour of sleep now for the SR attempts thanks to the change back to DST.
On Mar 17, 2010, at 9:45 AM, jim_kr1s wrote:
For the last few months I've been working on a new antenna for my PL-380. Now I have one that does just what I want, and it cost me less than $10.00. It's a 23-inch diameter, three-turn circular loop, matched to the radio through a 4:1 ferrite-toroid transformer. The transformer secondary replaces the internal antenna. This antenna requires no separate tuning adjustment; all tuning is done by the on-chip varactor. Does it work? You betcha! Signal strengths and nulling are exceptional. Now I just tune the radio to a frequency and swing the loop around for best reception or nulling. Last night and this morning it helped me add three new stations to my log.
This isn't a project for everyone. As built, it replaces the radio's internal antenna. Because there are bound to be differences in antenna construction, some tweaking of the impedance-matching transformer will improve performance. If you have the experience to perform this modification, all you need to know is here: http://kr1s.kearman.com/ html/hooploop. html Write me off-list if you have questions. jkearman at att dot net
Here are the loggings. Times in UTC.
03-16 2300 1150 WGBR Goldsboro NC Ad for crazywayno.com, ID 2310Z, Prime Time in the ACC 2330 1580 WCCF Punta Gorda FL Talk, local ads Florida #139 03-17 0300 1250 WTMA Charleston SC Talk, CBS news 1130 1160 WTEL Red Springs NC Church ann, ad Freedom Gospel Hour
Current ULR total, 405 stations.
73,
Jim, KR1S
http://kr1s.kearman.com/
jim_kr1s <jkearman@...>
--- In ultralightdx@..., Tony Germanotta wrote:
> Do you notice any improvement over just inductively coupling the 380 with your outboard loop? Other than no need to twiddle the knob for a peak? It should null better with no internal antenna at play.
You get much more signal into the receiver this way. Given the size difference between this antenna and the Terk, you would expect a 2-dB increase in signal strength, but it's much greater. That has to be because this antenna is more tightly coupled to the resonator. How much signal you can handle depends on where you are and the frequencies you want to use. If you live in the Pacific NW and want to DX TPs, most of them are low in the band, and there aren't a lot of locals on nearby channels. Then you can use all the gain you can get, and nulling is important, but secondary. Down here, with more than 200 stations in my own state and more than 100 just south of me in Cuba, more gain only makes more problems. I need to null some of this stuff, not make it stronger.
I have an old Zenith Royal 705, which is correctly called a hot receiver. It has a long loop that nulls well, and you wrap a coupling loop around it without tearing apart the radio. I tried coupling the Terk into it. Up to 3 turns, all's well. Any more than that and the receiver overloads and becomes useless. In another location, with fewer strong signals, it might be great. The DSP chip was designed for use with small antennas. As I mentioned, even with only the small toroid in place, it picked up several stations.
> But you lose the ability to carefully position the two antennas for some physical, rather than electronic, signal phasing to eliminate backside signals.
I never could phase the two antennas. Mostly I found having the internal antenna in place was a nuisance. Here are two, 5-second recordings as it's turned 90 degrees. One is R Enciclopedia, I forget what the other one was.
http://kearman.com/images/null1.mp3
http://kearman.com/images/null2-encic.mp3
> Have you considered a loop using a turn or two around an interior door? That would give you a really large capture area, and the door can be rotated through at least half of a compass which shouldn't be a problem if you pick the right door.
This condo is a good Faraday shield. The loop needs to be near the window to work. Anything inside won't pick up much. The photo shows the antenna in its operating location, atop the parts cabinets and above the test equipment. It's easy to reach up and twirl it; reaching over to adjust a Terk loop was getting old, as was having to reach up to the radio on that turntable after I modified the internal antenna. That room is the only place in the condo where I get sigs through a window. I could relocate the bench, but I don't want to move all that gear! Besides, I need to stay close to the coffee pot.
> I wonder how well that loop would work with the PL-360. Would you even need the matching transformer?
I assume you would, and that the PL-360 uses a loop in the range of 300 uH, like the others. It would facilitate plugging in a transformer and loop, but the radio itself is pretty short of features.
>
> And I've been meaning to echo the congratulations on your amazing DX success. At least you get an extra hour of sleep now for the SR attempts thanks to the change back to DST.
It took me a couple of days to wrap up this project. Yesterday morning the radio was apart on the bench, and I slept until 9. What a luxury! But if I'm ever going to catch up to Rob, John and other 600-800-stations mob, I'll have to keep getting up early.
73,
Jim, KR1S
http://kr1s.kearman.com/
Tony Germanotta
Yea physical phasing is all smoke and mirrors and probably a lot of imagination. And the bigger the disparity in size between the two antennas, the tougher to find that sweet spot, I have found.
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The antenna produces very nice nulls on those samples. Just the thing to sort through pests.
I predict your window perch will be hopping with signals.
I have an old brick home that attenuates but doesn't obliterate signals. I also have big bay windows in the front and back of the house, (north and south) where I can plop my loops when it is too cold, hot or buggy to head to the back yard. But it is amazing what a little stroll through the hallways can sometimes accomplish, with signals opening up, probably more by getting away from some electronic interference than an actual portal to the ethers. Then again, once you move you attribute it to the location change and it really could just be the ionosphere wrinkling. Still, you have to get your exercise where you can. And now that you don't have to tune your loop, you're going to need to spend double the time on the regen radios just to keep in shape. Can't let those twiddling muscles go flabby.
On Mar 17, 2010, at 1:27 PM, jim_kr1s wrote:
--- In ultralightdx@yahoogroups. com, Tony Germanotta ...> wrote:
> Do you notice any improvement over just inductively coupling the 380 with your outboard loop? Other than no need to twiddle the knob for a peak? It should null better with no internal antenna at play.
You get much more signal into the receiver this way. Given the size difference between this antenna and the Terk, you would expect a 2-dB increase in signal strength, but it's much greater. That has to be because this antenna is more tightly coupled to the resonator. How much signal you can handle depends on where you are and the frequencies you want to use. If you live in the Pacific NW and want to DX TPs, most of them are low in the band, and there aren't a lot of locals on nearby channels. Then you can use all the gain you can get, and nulling is important, but secondary. Down here, with more than 200 stations in my own state and more than 100 just south of me in Cuba, more gain only makes more problems. I need to null some of this stuff, not make it stronger.
I have an old Zenith Royal 705, which is correctly called a hot receiver. It has a long loop that nulls well, and you wrap a coupling loop around it without tearing apart the radio. I tried coupling the Terk into it. Up to 3 turns, all's well. Any more than that and the receiver overloads and becomes useless. In another location, with fewer strong signals, it might be great. The DSP chip was designed for use with small antennas. As I mentioned, even with only the small toroid in place, it picked up several stations.
> But you lose the ability to carefully position the two antennas for some physical, rather than electronic, signal phasing to eliminate backside signals.
I never could phase the two antennas. Mostly I found having the internal antenna in place was a nuisance. Here are two, 5-second recordings as it's turned 90 degrees. One is R Enciclopedia, I forget what the other one was.
http://kearman.com/images/ null1.mp3
http://kearman.com/images/ null2-encic. mp3
> Have you considered a loop using a turn or two around an interior door? That would give you a really large capture area, and the door can be rotated through at least half of a compass which shouldn't be a problem if you pick the right door.
This condo is a good Faraday shield. The loop needs to be near the window to work. Anything inside won't pick up much. The photo shows the antenna in its operating location, atop the parts cabinets and above the test equipment. It's easy to reach up and twirl it; reaching over to adjust a Terk loop was getting old, as was having to reach up to the radio on that turntable after I modified the internal antenna. That room is the only place in the condo where I get sigs through a window. I could relocate the bench, but I don't want to move all that gear! Besides, I need to stay close to the coffee pot.
> I wonder how well that loop would work with the PL-360. Would you even need the matching transformer?
I assume you would, and that the PL-360 uses a loop in the range of 300 uH, like the others. It would facilitate plugging in a transformer and loop, but the radio itself is pretty short of features.
>
> And I've been meaning to echo the congratulations on your amazing DX success. At least you get an extra hour of sleep now for the SR attempts thanks to the change back to DST.
It took me a couple of days to wrap up this project. Yesterday morning the radio was apart on the bench, and I slept until 9. What a luxury! But if I'm ever going to catch up to Rob, John and other 600-800-stations mob, I'll have to keep getting up early.
73,
Jim, KR1S
http://kr1s.kearman.com/
jim_kr1s <jkearman@...>
--- In ultralightdx@..., Tony Germanotta wrote:
>
> Can't let those twiddling muscles go flabby.
Just for kicks I held the Zenith inside the loop and tuned in a station. Then I turned on the PL-380 and tuned in the same station. Sure enough, the signal in the Zenith perked way up. So the next project will be, Turn Your DSP Radio Into An Antenna Tuner For Your Regen.
73,
Jim, KR1S
http://kr1s.kearman.com/
Tony Germanotta
That's great. Just remember to put the DSP Radio into a grounded metal box so it can't cause any interference and then tune away on your regen.
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I find that lately I am just going barefoot most of the time. Even when I use a SAT to hone in on a station, I then go back, detune it, turn it off axis and see if I can't make it an unassisted copy.
I'll probably wind up moving entirely to my Sony SRF-85 down the line (it's the sports model), but I do so love the digital display and 1Khz tuning of my PL-310.
On Mar 17, 2010, at 3:53 PM, jim_kr1s wrote:
--- In ultralightdx@yahoogroups. com, Tony Germanotta ...> wrote:
>
> Can't let those twiddling muscles go flabby.
Just for kicks I held the Zenith inside the loop and tuned in a station. Then I turned on the PL-380 and tuned in the same station. Sure enough, the signal in the Zenith perked way up. So the next project will be, Turn Your DSP Radio Into An Antenna Tuner For Your Regen.
73,
Jim, KR1S
http://kr1s.kearman.com/
Chris Knight
>So the next project will be, Turn Your DSP Radio Into An Antenna Tuner For Your Regen. <
We've seen a DSP Radio function as an inductance meter. So, why not as an Antenna Tuner? These things are really versatile, but can they make coffee?
73,
Chris
From: jim_kr1s
To: ultralightdx@...
Sent: Wed, March 17, 2010 1:53:35 PM
Subject: [ultralightdx] Re: New antenna, new loggings
--- In ultralightdx@ yahoogroups. com, Tony Germanotta wrote:
>
> Can't let those twiddling muscles go flabby.
Just for kicks I held the Zenith inside the loop and tuned in a station. Then I turned on the PL-380 and tuned in the same station. Sure enough, the signal in the Zenith perked way up. So the next project will be, Turn Your DSP Radio Into An Antenna Tuner For Your Regen.
73,
Jim, KR1S
http://kr1s. kearman.com/
sdwillingham
Nice! Sounds like you've designed a sweet DXing antenna at a bargain price. Also a very reasonable project for relative novices.
-Scott-
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-Scott-
--- In ultralightdx@..., "jim_kr1s" <jkearman@...> wrote:
--- In ultralightdx@..., Tony Germanotta
<germanotta.tony@> wrote:Just for kicks I held the Zenith inside the loop and tuned in a station.
Can't let those twiddling muscles go flabby.
Then I turned on the PL-380 and tuned in the same station. Sure enough,
the signal in the Zenith perked way up. So the next project will be,
Turn Your DSP Radio Into An Antenna Tuner For Your Regen.
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
jim_kr1s <jkearman@...>
--- In ultralightdx@..., "sdwillingham" wrote:
>
> Nice! Sounds like you've designed a sweet DXing antenna at a bargain price. Also a very reasonable project for relative novices.
Thanks, Scott. If someone wanted to rewind the internal ferrite rod, and added 13-15 turns around the center of the new winding, it would work that way, but many signals would leak into the internal antenna. That chip has lots of gain. In desperation I wrapped a piece of anti-static bag (like transistors and ICs are shipped in) around the toroid, which knocked down a couple of locals about 20 dB when no antenna is connected.
73,
Jim, KR1S
http://kr1s.kearman.com/
Rik
Jim - I really don't understand the theory well enough to follow exactly what you are doing. I had hoped a unit which plugged into the stock model PL-360 could be made and sold by some enterprising member for fumble fingered folks like me. I guess the PL-360 lacks too many important features, like the adjustable selectivity to interest anyone. It might be nice to try one on a TERK or the TECSUN small loop though. Now if I can only stop buying larger radios on eBay, maybe I will order more ULR's! - FARMERIK
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--- In ultralightdx@..., "jim_kr1s" <jkearman@...> wrote:
--- In ultralightdx@..., "sdwillingham" <sdwillingham@>
wrote:price. Also a very reasonable project for relative novices.
Nice! Sounds like you've designed a sweet DXing antenna at a bargain
Thanks, Scott. If someone wanted to rewind the internal ferrite rod, and
added 13-15 turns around the center of the new winding, it would work
that way, but many signals would leak into the internal antenna. That
chip has lots of gain. In desperation I wrapped a piece of anti-static
bag (like transistors and ICs are shipped in) around the toroid, which
knocked down a couple of locals about 20 dB when no antenna is
connected.
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
jim_kr1s <jkearman@...>
--- In ultralightdx@..., "farmerik" wrote:
>
> Jim - I really don't understand the theory well enough to follow exactly what you are doing. I had hoped a unit which plugged into the stock model PL-360 could be made and sold by some enterprising member for fumble fingered folks like me. I guess the PL-360 lacks too many important features, like the adjustable selectivity to interest anyone. It might be nice to try one on a TERK or the TECSUN small loop though. Now if I can only stop buying larger radios on eBay, maybe I will order more ULR's! - FARMERIK
Good luck cornering the market on radios! My system is not complicated. The existing antenna is replaced by a toroid, which is less susceptible to picking up signals than a bar. Now the radio is happy, as it sees a tunable LC network across the MW band. When you match impedances, you obtain the greatest energy transfer from one circuit to the next. Because my hoop loop has only 3 turns of wire, it has a lower impedance than the 60-turn resonator winding on the toroid. I calculated that a 15-turn winding, wound over the 60-turn winding, would be about right. It worked well, but it's always worth adding or removing turns to get the best results across the band. As it happened, on mine, 13 turns was the lucky number. I was quite surprised at the difference removing only two turns made, and the increase was uniform across the band.
Why use a 3-turn antenna? The low impedance allows use of low-impedance balanced feed line, in this case small-gauge speaker wire! Also, the quilt hoops are less than an inch wide. It would take about 15 turns to make a coil that resonated with the standard 365-pF variable cap (or the varactor in the radio). That many turns so close together would make it hard to tune the loop to frequencies higher in the band, because of the inherent "self capacitance" of the closely spaced windings. I know Tecsun is getting away with it on their small loops; you can see the windings. I commend them! My experience with high-inductance loop antennas using close spacing hasn't been good.
I don't think the PL-360 is DXer friendly. You could plug my system into the PL-360 in place of its antenna, but you'd need a small box to contain the matching transformer, and it would eliminate the one advantage of the -360, its small size.
The PL-360 apparently duplicates the tuning arrangement of the PL-300/wt, PL--310 and PL-380. An on-chip voltage-variable capacitor (VVC) automatically tunes the antenna coil on LW and MW. (As built, tuning on LW is not really happening, as the coil inductance is too low.) The Terk, Tecsun and SAT antennas contain their own tuning capacitors, which resonate their antenna coils just like the on-chip VVC in the Tecsun radios. So if you plugged one of those antennas directly into the radio, you'd have the on-chip VVC in parallel with the capacitor in the external antenna. I don't think it would work as intended on MW. I've been fighting an invasion of space-alien body snatchers. Once I can stay on my feet for more than a few minutes I'll try connecting the Terk directly to my modified PL-380 just to see.
73,
Jim, KR1S
http://kr1s.kearman.com/
Rik
Thanks for the additional explanation, it is clearer to me now.
What sort of loop would I wind if I wanted to connect it directly, and not use a torrid [or other] transformer?
I believe I would need the radio right at the base of the loop, but I can do that here OK. I use my 2 foot and 4 foot loops hung from the ceiling all the time without a cap. No shielding in my walls to speak of. - FARMERIK
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What sort of loop would I wind if I wanted to connect it directly, and not use a torrid [or other] transformer?
I believe I would need the radio right at the base of the loop, but I can do that here OK. I use my 2 foot and 4 foot loops hung from the ceiling all the time without a cap. No shielding in my walls to speak of. - FARMERIK
--- In ultralightdx@..., "jim_kr1s" <jkearman@...> wrote:
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:exactly what you are doing. I had hoped a unit which plugged into the
Jim - I really don't understand the theory well enough to follow
stock model PL-360 could be made and sold by some enterprising member
for fumble fingered folks like me. I guess the PL-360 lacks too many
important features, like the adjustable selectivity to interest anyone.
It might be nice to try one on a TERK or the TECSUN small loop though.
Now if I can only stop buying larger radios on eBay, maybe I will order
more ULR's! - FARMERIK
Good luck cornering the market on radios! My system is not complicated.
The existing antenna is replaced by a toroid, which is less susceptible
to picking up signals than a bar. Now the radio is happy, as it sees a
tunable LC network across the MW band. When you match impedances, you
obtain the greatest energy transfer from one circuit to the next.
Because my hoop loop has only 3 turns of wire, it has a lower impedance
than the 60-turn resonator winding on the toroid. I calculated that a
15-turn winding, wound over the 60-turn winding, would be about right.
It worked well, but it's always worth adding or removing turns to get
the best results across the band. As it happened, on mine, 13 turns was
the lucky number. I was quite surprised at the difference removing only
two turns made, and the increase was uniform across the band.
Why use a 3-turn antenna? The low impedance allows use of low-impedance
balanced feed line, in this case small-gauge speaker wire! Also, the
quilt hoops are less than an inch wide. It would take about 15 turns to
make a coil that resonated with the standard 365-pF variable cap (or the
varactor in the radio). That many turns so close together would make it
hard to tune the loop to frequencies higher in the band, because of the
inherent "self capacitance" of the closely spaced windings. I know
Tecsun is getting away with it on their small loops; you can see the
windings. I commend them! My experience with high-inductance loop
antennas using close spacing hasn't been good.
I don't think the PL-360 is DXer friendly. You could plug my system into
the PL-360 in place of its antenna, but you'd need a small box to
contain the matching transformer, and it would eliminate the one
advantage of the -360, its small size.
The PL-360 apparently duplicates the tuning arrangement of the
PL-300/wt, PL--310 and PL-380. An on-chip voltage-variable capacitor
(VVC) automatically tunes the antenna coil on LW and MW. (As built,
tuning on LW is not really happening, as the coil inductance is too
low.) The Terk, Tecsun and SAT antennas contain their own tuning
capacitors, which resonate their antenna coils just like the on-chip VVC
in the Tecsun radios. So if you plugged one of those antennas directly
into the radio, you'd have the on-chip VVC in parallel with the
capacitor in the external antenna. I don't think it would work as
intended on MW. I've been fighting an invasion of space-alien body
snatchers. Once I can stay on my feet for more than a few minutes I'll
try connecting the Terk directly to my modified PL-380 just to see.
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
jim_kr1s <jkearman@...>
--- In ultralightdx@..., "farmerik" wrote:
>
> Thanks for the additional explanation, it is clearer to me now.
> What sort of loop would I wind if I wanted to connect it directly, and not use a torrid [or other] transformer?
In that case, the inductance of the antenna has to resonate directly with the varactor diode on the chip. Taking into account stray capacitance in the connecting wires and the loop itself, design for about 240 uH. This calculator should get you close. http://electronbunker.sasktelwebsite.net/InductanceCalc.html It gives more accurate results for large air-loop coils than the one called "Professor Coyle."
73,
Jim, KR1S
http://kr1s.kearman.com/
Hi Tim,
Thanks for the reference to the PVC Loop article, also posted at http://www.mediafire.com/?igw1zjwfzmw .
Dimensions and spacing for loops from 18" up to 9' (side sizes) are given in a
table, along with weights and cost. All of these loops have actually been
constructed, and tested.
In constructing any AM-DXing loop, it's important to remember that size
does matter. If you want better DX performance, build one of the bigger
loops :-)
73, Gary
In a message dated 3/21/2010 8:55:21 A.M. Pacific Daylight Time,
timchandler2001@... writes:
Don't forget Gary's article in this group's Files section, on PVC loop antennas:
http://tinyurl.com/yjfd67e
This calculator may also prove useful although it does not apparently take into account "distributed capacitance" when the windings are closer together, but with .5 inch spacing you are probably not affected that much:
http://www.angelfire.com/mb/ amandx/loop. html
Tim C.
--- In ultralightdx@yahoogroups. com, "farmerik" .> wrote:
>
>
> Still thinking! The circumference of a 30 inch loop is quite similar to the perimeter of a 2 foot square, does changing the shape make much difference?
>
> If my memory of High school geometry is correct, a round loop form could be made from a strip of Masonite 8 feet long which would be close to 30 inches. Of course it would need 'spokes' or spreaders to KEEP it round. A 2 foot square loop should be easier to make, if it is just about as good.
>
> It's Electronics 101, but I still don't have a clear understanding of the difference of Impedance and Inductance. Do you happen to know of an Impedance calculator for loops this big? What I am wondering is there transmission line I could use to mount the loops in the attic, pointing in a few different directions, and choose the one I want by connecting it to the radio separately. I just have no idea if that is possible or impossible. - FARMERIK
>
>
> --- In ultralightdx@yahoogroups. com, "farmerik" wrote:
> >
> >
> > OK, now I am getting somewhere, at least in my mind. A 30 inch diameter, with 1/2 inch spacing [I think I need that to prevent capacitance between windings?] gets me to 258 uH with 15 turns and the wire I chose.
> > Now I need to think of a coil form that big. Sonotube? Made up from long strips of Masonite? If I can't come up with a round form, would you happen to know how to calculate for a square one?
> >
> > - FARMERIK
> >
> >
> > --- In ultralightdx@yahoogroups. com, "jim_kr1s" wrote:
> > >
> > >
> > > --- In ultralightdx@yahoogroups. com, "farmerik" wrote:
> > > >
> > > > Thanks for the additional explanation, it is clearer to me now.
> > > > What sort of loop would I wind if I wanted to connect it directly, and
> > > not use a torrid [or other] transformer?
> > >
> > > In that case, the inductance of the antenna has to resonate directly
> > > with the varactor diode on the chip. Taking into account stray
> > > capacitance in the connecting wires and the loop itself, design for
> > > about 240 uH. This calculator should get you close.
> > > http://electronbunker.sasktelwebsit e.net/Inductance Calc.html
> > > <http://electronbunker.sasktelwebsit e.net/Inductance Calc.html> It
> > > gives more accurate results for large air-loop coils than the one called
> > > "Professor Coyle."
> > >
> > > 73,
> > >
> > > Jim, KR1S
> > > http://kr1s.kearman.com/ <http://kr1s. kearman.com/>
> > >
> >
>
Rik
OK, now I am getting somewhere, at least in my mind. A 30 inch diameter, with 1/2 inch spacing [I think I need that to prevent capacitance between windings?] gets me to 258 uH with 15 turns and the wire I chose.
Now I need to think of a coil form that big. Sonotube? Made up from long strips of Masonite? If I can't come up with a round form, would you happen to know how to calculate for a square one?
- FARMERIK
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Now I need to think of a coil form that big. Sonotube? Made up from long strips of Masonite? If I can't come up with a round form, would you happen to know how to calculate for a square one?
- FARMERIK
--- In ultralightdx@..., "jim_kr1s" <jkearman@...> wrote:
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:not use a torrid [or other] transformer?
Thanks for the additional explanation, it is clearer to me now.
What sort of loop would I wind if I wanted to connect it directly, and
In that case, the inductance of the antenna has to resonate directly
with the varactor diode on the chip. Taking into account stray
capacitance in the connecting wires and the loop itself, design for
about 240 uH. This calculator should get you close.
http://electronbunker.sasktelwebsite.net/InductanceCalc.html
<http://electronbunker.sasktelwebsite.net/InductanceCalc.html> It
gives more accurate results for large air-loop coils than the one called
"Professor Coyle."
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
Rik
Still thinking! The circumference of a 30 inch loop is quite similar to the perimeter of a 2 foot square, does changing the shape make much difference?
If my memory of High school geometry is correct, a round loop form could be made from a strip of Masonite 8 feet long which would be close to 30 inches. Of course it would need 'spokes' or spreaders to KEEP it round. A 2 foot square loop should be easier to make, if it is just about as good.
It's Electronics 101, but I still don't have a clear understanding of the difference of Impedance and Inductance. Do you happen to know of an Impedance calculator for loops this big? What I am wondering is there transmission line I could use to mount the loops in the attic, pointing in a few different directions, and choose the one I want by connecting it to the radio separately. I just have no idea if that is possible or impossible. - FARMERIK
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If my memory of High school geometry is correct, a round loop form could be made from a strip of Masonite 8 feet long which would be close to 30 inches. Of course it would need 'spokes' or spreaders to KEEP it round. A 2 foot square loop should be easier to make, if it is just about as good.
It's Electronics 101, but I still don't have a clear understanding of the difference of Impedance and Inductance. Do you happen to know of an Impedance calculator for loops this big? What I am wondering is there transmission line I could use to mount the loops in the attic, pointing in a few different directions, and choose the one I want by connecting it to the radio separately. I just have no idea if that is possible or impossible. - FARMERIK
--- In ultralightdx@..., "farmerik" <farmerik@...> wrote:
OK, now I am getting somewhere, at least in my mind. A 30 inch diameter, with 1/2 inch spacing [I think I need that to prevent capacitance between windings?] gets me to 258 uH with 15 turns and the wire I chose.
Now I need to think of a coil form that big. Sonotube? Made up from long strips of Masonite? If I can't come up with a round form, would you happen to know how to calculate for a square one?
- FARMERIK
--- In ultralightdx@..., "jim_kr1s" <jkearman@> wrote:
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:not use a torrid [or other] transformer?
Thanks for the additional explanation, it is clearer to me now.
What sort of loop would I wind if I wanted to connect it directly, and
In that case, the inductance of the antenna has to resonate directly
with the varactor diode on the chip. Taking into account stray
capacitance in the connecting wires and the loop itself, design for
about 240 uH. This calculator should get you close.
http://electronbunker.sasktelwebsite.net/InductanceCalc.html
<http://electronbunker.sasktelwebsite.net/InductanceCalc.html> It
gives more accurate results for large air-loop coils than the one called
"Professor Coyle."
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
osage_archer
Don't forget Gary's article in this group's Files section, on PVC loop antennas:
http://tinyurl.com/yjfd67e
This calculator may also prove useful although it does not apparently take into account "distributed capacitance" when the windings are closer together, but with .5 inch spacing you are probably not affected that much:
http://www.angelfire.com/mb/amandx/loop.html
Tim C.
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Show quoted text
http://tinyurl.com/yjfd67e
This calculator may also prove useful although it does not apparently take into account "distributed capacitance" when the windings are closer together, but with .5 inch spacing you are probably not affected that much:
http://www.angelfire.com/mb/amandx/loop.html
Tim C.
--- In ultralightdx@..., "farmerik" <farmerik@...> wrote:
Still thinking! The circumference of a 30 inch loop is quite similar to the perimeter of a 2 foot square, does changing the shape make much difference?
If my memory of High school geometry is correct, a round loop form could be made from a strip of Masonite 8 feet long which would be close to 30 inches. Of course it would need 'spokes' or spreaders to KEEP it round. A 2 foot square loop should be easier to make, if it is just about as good.
It's Electronics 101, but I still don't have a clear understanding of the difference of Impedance and Inductance. Do you happen to know of an Impedance calculator for loops this big? What I am wondering is there transmission line I could use to mount the loops in the attic, pointing in a few different directions, and choose the one I want by connecting it to the radio separately. I just have no idea if that is possible or impossible. - FARMERIK
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:
OK, now I am getting somewhere, at least in my mind. A 30 inch diameter, with 1/2 inch spacing [I think I need that to prevent capacitance between windings?] gets me to 258 uH with 15 turns and the wire I chose.
Now I need to think of a coil form that big. Sonotube? Made up from long strips of Masonite? If I can't come up with a round form, would you happen to know how to calculate for a square one?
- FARMERIK
--- In ultralightdx@..., "jim_kr1s" <jkearman@> wrote:
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:not use a torrid [or other] transformer?
Thanks for the additional explanation, it is clearer to me now.
What sort of loop would I wind if I wanted to connect it directly, and
In that case, the inductance of the antenna has to resonate directly
with the varactor diode on the chip. Taking into account stray
capacitance in the connecting wires and the loop itself, design for
about 240 uH. This calculator should get you close.
http://electronbunker.sasktelwebsite.net/InductanceCalc.html
<http://electronbunker.sasktelwebsite.net/InductanceCalc.html> It
gives more accurate results for large air-loop coils than the one called
"Professor Coyle."
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
Rik
I've spent hours looking over Gary's work on all those tuned loops. That is a great resource, and must have taken a long time to build all of those.
The formula Bruce Carter put up gives a 12 turn 24 inch square loop about the right inductance with 0.5 inch spacing. I tried a few other spacings, and I can't quite follow the effect. I could also add a cap when I wanted too. I have one of those with a built in gear reduction, sold for use in crystal sets which max's out around 400 pF If I remember correctly,
For the DSP radios, I'd like to let the internal vari-cap or what ever it is, match or tune the loop. On my G8, tuning the TERK or SAT is difficult because the sampling rate for the meter is so slow, and you have to keep retuning the radio to adjust. I find that more difficult than tuning a Regen set! - FARMERIK
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Show quoted text
The formula Bruce Carter put up gives a 12 turn 24 inch square loop about the right inductance with 0.5 inch spacing. I tried a few other spacings, and I can't quite follow the effect. I could also add a cap when I wanted too. I have one of those with a built in gear reduction, sold for use in crystal sets which max's out around 400 pF If I remember correctly,
For the DSP radios, I'd like to let the internal vari-cap or what ever it is, match or tune the loop. On my G8, tuning the TERK or SAT is difficult because the sampling rate for the meter is so slow, and you have to keep retuning the radio to adjust. I find that more difficult than tuning a Regen set! - FARMERIK
--- In ultralightdx@..., "osage_archer" <timchandler2001@...> wrote:
Don't forget Gary's article in this group's Files section, on PVC loop antennas:
http://tinyurl.com/yjfd67e
This calculator may also prove useful although it does not apparently take into account "distributed capacitance" when the windings are closer together, but with .5 inch spacing you are probably not affected that much:
http://www.angelfire.com/mb/amandx/loop.html
Tim C.
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:
Still thinking! The circumference of a 30 inch loop is quite similar to the perimeter of a 2 foot square, does changing the shape make much difference?
If my memory of High school geometry is correct, a round loop form could be made from a strip of Masonite 8 feet long which would be close to 30 inches. Of course it would need 'spokes' or spreaders to KEEP it round. A 2 foot square loop should be easier to make, if it is just about as good.
It's Electronics 101, but I still don't have a clear understanding of the difference of Impedance and Inductance. Do you happen to know of an Impedance calculator for loops this big? What I am wondering is there transmission line I could use to mount the loops in the attic, pointing in a few different directions, and choose the one I want by connecting it to the radio separately. I just have no idea if that is possible or impossible. - FARMERIK
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:
OK, now I am getting somewhere, at least in my mind. A 30 inch diameter, with 1/2 inch spacing [I think I need that to prevent capacitance between windings?] gets me to 258 uH with 15 turns and the wire I chose.
Now I need to think of a coil form that big. Sonotube? Made up from long strips of Masonite? If I can't come up with a round form, would you happen to know how to calculate for a square one?
- FARMERIK
--- In ultralightdx@..., "jim_kr1s" <jkearman@> wrote:
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:not use a torrid [or other] transformer?
Thanks for the additional explanation, it is clearer to me now.
What sort of loop would I wind if I wanted to connect it directly, and
In that case, the inductance of the antenna has to resonate directly
with the varactor diode on the chip. Taking into account stray
capacitance in the connecting wires and the loop itself, design for
about 240 uH. This calculator should get you close.
http://electronbunker.sasktelwebsite.net/InductanceCalc.html
<http://electronbunker.sasktelwebsite.net/InductanceCalc.html> It
gives more accurate results for large air-loop coils than the one called
"Professor Coyle."
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
Rik
Has anyone seen a comparison between ferrite rod antenna and air core loops which gives the sizes which are about equal in signal strength? - FARMERIK
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--- In ultralightdx@..., D1028Gary@... wrote:
Hi Tim,
Thanks for the reference to the PVC Loop article, also posted at
_http://www.mediafire.com/?igw1zjwfzmw_ (http://www.mediafire.com/?igw1zjwfzmw) .
Dimensions and spacing for loops from 18" up to 9' (side sizes) are given in a
table, along with weights and cost. All of these loops have actually been
constructed, and tested.
In constructing any AM-DXing loop, it's important to remember that size
does matter. If you want better DX performance, build one of the bigger loops
:-)
73, Gary
In a message dated 3/21/2010 8:55:21 A.M. Pacific Daylight Time,
timchandler2001@... writes:
Don't forget Gary's article in this group's Files section, on PVC loop
antennas:
_http://tinyurl.http://tiny_ (http://tinyurl.com/yjfd67e)
This calculator may also prove useful although it does not apparently take
into account "distributed capacitance" when the windings are closer
together, but with .5 inch spacing you are probably not affected that much:
_http://www.angelfirhttp://wwhttp://www.ahttp_
(http://www.angelfire.com/mb/amandx/loop.html)
Tim C.
--- In _ultralightdx@ultralightdxult_ (mailto:ultralightdx@...)
, "farmerik" <farmerik@...> wrote:the perimeter of a 2 foot square, does changing the shape make much
Still thinking! The circumference of a 30 inch loop is quite similar to
difference?be made from a strip of Masonite 8 feet long which would be close to 30
If my memory of High school geometry is correct, a round loop form could
inches. Of course it would need 'spokes' or spreaders to KEEP it round. A 2
foot square loop should be easier to make, if it is just about as good.the difference of Impedance and Inductance. Do you happen to know of an
It's Electronics 101, but I still don't have a clear understanding of
Impedance calculator for loops this big? What I am wondering is there
transmission line I could use to mount the loops in the attic, pointing in a few
different directions, and choose the one I want by connecting it to the radio
separately. I just have no idea if that is possible or impossible. - FARMERIK(mailto:ultralightdx@...) , "farmerik" <farmerik@> wrote:
--- In _ultralightdx@ultralightdxult_diameter, with 1/2 inch spacing [I think I need that to prevent capacitance
OK, now I am getting somewhere, at least in my mind. A 30 inch
between windings?] gets me to 258 uH with 15 turns and the wire I chose.long strips of Masonite? If I can't come up with a round form, would youNow I need to think of a coil form that big. Sonotube? Made up from
happen to know how to calculate for a square one?(mailto:ultralightdx@...) , "jim_kr1s" <jkearman@> wrote:
- FARMERIK
--- In _ultralightdx@ultralightdxult_(mailto:ultralightdx@...) , "farmerik" <farmerik@> wrote:
--- In _ultralightdx@ultralightdxult_directly, and> > > What sort of loop would I wind if I wanted to connect it> Thanks for the additional explanation, it is clearer to me now.(http://electronbunker.sasktelwebsite.net/InductanceCalc.html)not use a torrid [or other] transformer?
In that case, the inductance of the antenna has to resonate directly
with the varactor diode on the chip. Taking into account stray
capacitance in the connecting wires and the loop itself, design for
about 240 uH. This calculator should get you close.
_http://electronbunkhttp://electronbhttp://electronbhttp://el_> > <_http://electronbunkhttp://electronbhttp://electronbhttp://el_(http://electronbunker.sasktelwebsite.net/InductanceCalc.html) > Itcalledgives more accurate results for large air-loop coils than the one<_http://kr1s.http://kr1s._ (http://kr1s.kearman.com/) >> > 73,"Professor Coyle."
Jim, KR1S
_http://kr1s.http://kr1s._ (http://kr1s.kearman.com/)> >
jim_kr1s <jkearman@...>
--- In ultralightdx@..., "farmerik" wrote:
>
>
> Still thinking! The circumference of a 30 inch loop is quite similar to the perimeter of a 2 foot square, does changing the shape make much difference?
Not really.
> It's Electronics 101, but I still don't have a clear understanding of the difference of Impedance and Inductance. Do you happen to know of an Impedance calculator for loops this big?
For an inductor, impedance (reactance) varies in direct proportion to frequency. What we're talking about is making an inductor that resonates with the varactor. As the varactor's range is known, we can calculate the right inductance. Impedance in this case is irrelevant. No matter how you build it, a coil of inductance L will always have the same impedance (reactance) at any given frequency.
A few minutes with a search engine should turn up some tutorials on inductance, impedance and resonance.
> What I am wondering is there transmission line I could use to mount the loops in the attic, pointing in a few different directions, and choose the one I want by connecting it to the radio separately. I just have no idea if that is possible or impossible. - FARMERIK
It's possible, but you've opened a whole 'nother area that probably interests very few ULR DXers. Once I'm back on my feet I'll send you an email. Anyone else who's interested may contact me off-list.
73,
Jim, KR1S
http://kr1s.kearman.com/