Date   

Re: Loopstick coil winding findings

Roy <roy.dyball@...>
 

Thank you all for your comments and added detailed explanations.

I forgot to mention one of my attempts. This entailed winding the loopstick coil in a bifilar configuration. A while ago when I was reading some of Tesla's work on pancake bifilar coils.  The notes contained  a hands on experiment to show the benefits of a bifilar solenoid coil compared to a standard coil. It just consisted of 100 turns of magnet wire wrapped around a nail then connected to a single cell. Paper clips where used and the number picked up where noted. The coil was then rewound in bifilar fashion with the same number of turns then connected to the same cell. It was noted that twice the number of paper clips could be picked up. This demonstrated the magnifying effect of bifilar winding.

I decided to wind a loopstick coil in this fashion. The first one was just close wound with the same dimensions as the non bifilar coil. It did not work any better, about the same. I then rewound it with single wire spacing but keeping the two wires parallel and together. It did not work any better than the single wire spaced coil. I then rewound it again placing the space between the windings. This one also did not show any improvement.

I had great hopes for the bifilar configuration. Normally with electromagnetism properties usually work in reverse. I have not given up on this and will try this again when I get the Amidon 61 rods

 

Roy. 

 
--- In ultralightdx@..., "ferrite61" >
> This is the CORRECTED post with CORRECT approximations:
>
>
> 1) Center the windings: keep them as far away from the ends as possible.
> 2) Space the turns 1 to 1 meaning the space between turns is the same as the
> COPPER wire diameter.
> 3) The length of the coil itself should be between 35% and 40% of the ferrite
> rod length to reinforce suggestion #1 above. This will optimally maximize the Q
> and the inductance increase.
> 4) Therefore some important numbers are needed in designing a ferrite-rod
> inductor.
> a) The copper wire diameter of the gauge used.
> b) The length and diameter of the ferrite rod.
> c) The length of the coil as prescribed. 40% of rod length is quite good. (3"
> per 7.5" rod)
> d) The number of turns allowed by maximizing the properties of the coil. For 3"
> of coil length one will wrap 1/2 of the turns provided by dividing the 3" length
> by the wire diameter. {Example: 3/0.01 x 0.5 = 150 turns of #30, and 3/0.02 x
> 0.5 = 75 turns of #24}
> e) The area of the ferrite rod X-section usually in the shape of an "O" = pi*
> (1/2diam)^2
> f) A very good approximation for the properties of the #61 Amidon rod. The rule
> of Thumb thats very accurate is to start with a length to diameter ratio of 4
> being a factor of 12. For each unit increase, add 3.9. {Example: at 8 to 1 this
> factor is 27.6, at 12 to 1 its 43.2}
> g) A very good approximation that deals with the coil length being shorter than
> the rod length. This factor is refered to as the "K factor" in various ferrite
> literature. I have never seen an "absolute" formula.
>
> Tuff math here no matter what... Best method accurate to 1% is as follows;
> Let R = length of rod / length of coil ( for 7.5" and 3" respective this is 2.5
> )
>
> R^(1/R^0.43) Using the example 2.5^(0.4^0.43) = 2.5^0.67435 = 1.855 So we have
> approximated K as 1.855 when the coil is centered, spaced 1 to 1, and is 40% of
> the rod length.
>
> h) An approximation of the Ue of the ferrite inductor becomes the factor in step
> f x K. In the ongoing example this is 43.2 x 1.855 or a Ue of about 80.136 when
> the rod is 12 times longer than its diameter, and the coil is 40% of the rod
> length and centered.
>
> i) We will need to consolidate some universal constants to make a rather simple
> inductance formula. The U0 (U sub zero) is defined as 4x pi x 10E-7 nH/cm, and
> there are 10000 Maxwells per Gauss of attraction: also pi from the determination
> of the X-section of the rod is consolidated. These three multiply as 0.03948
>
> We are now ready to form an equation that will closely approximate the ideal
> inductance (at low frequencies) of a ferrite rod wound to near ideal conditions
> of centering, wire-spacing and distance-to-end.
>
> K * factor * N^2 * r^2 / length of rod * 25.33
>
> N^2 is the square of the number of turns
> r^2 is the square of the radius of the ferrite rod
> 25.33 is the constants in step i placed in the denominator (1/0.039478)
>
> ALL measurements are in centimeters, since everything else is derived from the
> Metric System.
>
> For our example lets make the ferrite rod 5/8" diameter and 7.5" long for a
> ratio of 12 to 1.
> We will use #24 wire (0.02") for 75 turns in 3" length. The 5/8"diameter is
> 1.5875 cm: the radius is therefore 0.79375. The 7.5" length of the rod is
> 19.05cm. The final answer will be in microHenries of inductance (uH)
>
> 1.855 * 43.2 * 75^2 * 0.79375^2 / 25.33 * 19.05 = 284000 / 482.5365 = 588.5uH
>
> Note that if one tests the inductor at AM-BCB frequencies, the inductance will
> appear to increase. This is due to some losses of the rod (notably hysteresis),
> and can't be avoided. Un wrapping a turn or two usually helps.
>
> Paul S. in CT
>


Re: Loopstick coil winding findings

ferrite61 <dxrx@...>
 

This is the CORRECTED post with CORRECT approximations:


1) Center the windings: keep them as far away from the ends as possible.
2) Space the turns 1 to 1 meaning the space between turns is the same as the
COPPER wire diameter.
3) The length of the coil itself should be between 35% and 40% of the ferrite
rod length to reinforce suggestion #1 above. This will optimally maximize the Q
and the inductance increase.
4) Therefore some important numbers are needed in designing a ferrite-rod
inductor.
a) The copper wire diameter of the gauge used.
b) The length and diameter of the ferrite rod.
c) The length of the coil as prescribed. 40% of rod length is quite good. (3"
per 7.5" rod)
d) The number of turns allowed by maximizing the properties of the coil. For 3"
of coil length one will wrap 1/2 of the turns provided by dividing the 3" length
by the wire diameter. {Example: 3/0.01 x 0.5 = 150 turns of #30, and 3/0.02 x
0.5 = 75 turns of #24}
e) The area of the ferrite rod X-section usually in the shape of an "O" = pi*
(1/2diam)^2
f) A very good approximation for the properties of the #61 Amidon rod. The rule
of Thumb thats very accurate is to start with a length to diameter ratio of 4
being a factor of 12. For each unit increase, add 3.9. {Example: at 8 to 1 this
factor is 27.6, at 12 to 1 its 43.2}
g) A very good approximation that deals with the coil length being shorter than
the rod length. This factor is refered to as the "K factor" in various ferrite
literature. I have never seen an "absolute" formula.

Tuff math here no matter what... Best method accurate to 1% is as follows;
Let R = length of rod / length of coil ( for 7.5" and 3" respective this is 2.5
)

R^(1/R^0.43) Using the example 2.5^(0.4^0.43) = 2.5^0.67435 = 1.855 So we have
approximated K as 1.855 when the coil is centered, spaced 1 to 1, and is 40% of
the rod length.

h) An approximation of the Ue of the ferrite inductor becomes the factor in step
f x K. In the ongoing example this is 43.2 x 1.855 or a Ue of about 80.136 when
the rod is 12 times longer than its diameter, and the coil is 40% of the rod
length and centered.

i) We will need to consolidate some universal constants to make a rather simple
inductance formula. The U0 (U sub zero) is defined as 4x pi x 10E-7 nH/cm, and
there are 10000 Maxwells per Gauss of attraction: also pi from the determination
of the X-section of the rod is consolidated. These three multiply as 0.03948

We are now ready to form an equation that will closely approximate the ideal
inductance (at low frequencies) of a ferrite rod wound to near ideal conditions
of centering, wire-spacing and distance-to-end.

K * factor * N^2 * r^2 / length of rod * 25.33

N^2 is the square of the number of turns
r^2 is the square of the radius of the ferrite rod
25.33 is the constants in step i placed in the denominator (1/0.039478)

ALL measurements are in centimeters, since everything else is derived from the
Metric System.

For our example lets make the ferrite rod 5/8" diameter and 7.5" long for a
ratio of 12 to 1.
We will use #24 wire (0.02") for 75 turns in 3" length. The 5/8"diameter is
1.5875 cm: the radius is therefore 0.79375. The 7.5" length of the rod is
19.05cm. The final answer will be in microHenries of inductance (uH)

1.855 * 43.2 * 75^2 * 0.79375^2 / 25.33 * 19.05 = 284000 / 482.5365 = 588.5uH

Note that if one tests the inductor at AM-BCB frequencies, the inductance will
appear to increase. This is due to some losses of the rod (notably hysteresis),
and can't be avoided. Un wrapping a turn or two usually helps.

Paul S. in CT


Re: Loopstick coil winding findings

ferrite61 <dxrx@...>
 

OOOPS: I found a mistake in what I wrote here... at a 4 to 1 rod length to diameter, the factor is 12, NOT 16 as I previously wrote... therefore the factor at 12 to 1 is 43.2, NOT the 47.2 I wrote. This changes the answers yielded in the example. The CORRECTED formula in the example should read

1.855 * 43.2 * 75^2 * 0.79375^2 / 25.33 * 19.05 The correct approximation is therefore 284000 / 482.5365 = 588.5 uH

In my previous post, the #22 wire will therefore have an inductance of 364 uH, NOT the 400 reported in error.

Appologies

Paul S. in CT

--- In ultralightdx@..., "ferrite61" <dxrx@...> wrote:

Yes, Ben's work is essential for these. Dan McGillis also did some good leg work on this testing various lots of #61 mix and coming up with suitable values of factor and K. I would also recommend a download of the latest fair-rite magnetics catalog. It has charts for factor and K values, but no formula for K. I did a magnified chart interpretation, and offered an approximate solution when R is 2.5 to 3. I would note that using #21 wire in my example would have 53 turns properly spaced and centered with an inductance of about 320 uH, having a 27pF value at 1710kHz. Commonly, #22 wire is 59 turns with 400uH inductance. I wanted to keep the example building, so the reader gets a sense of how the formula-parts fit together.

Paul S. in CT

--- In ultralightdx@..., "jim_kr1s" <jkearman@> wrote:



--- In ultralightdx@..., "ferrite61" <dxrx@> wrote:

1.855 * 47.2 * 75^2 * 0.79375^2 / 25.33 * 19.05 = 310295.8 / 482.55365 = 643uH
Nice explanation, Paul. According to the Silicon Labs datasheet, the inductance should be between 180 and 450 uH (Si4730/31-C40, page 21). The current batch of chips may tune a 554-uH (or even perhaps 643-uH) inductor at 1710 kHz, but there's no guarantee the next batch will. Your suggestions re turns spacing and Litz wire mirror what I said in a previous post, based on work done by Ben Tongue. Using that information to build antennas that fall within SiLabs' recommendations is the best approach.

73,

Jim, KR1S


Re: Loopstick coil winding findings

ferrite61 <dxrx@...>
 

Yes, Ben's work is essential for these. Dan McGillis also did some good leg work on this testing various lots of #61 mix and coming up with suitable values of factor and K. I would also recommend a download of the latest fair-rite magnetics catalog. It has charts for factor and K values, but no formula for K. I did a magnified chart interpretation, and offered an approximate solution when R is 2.5 to 3. I would note that using #21 wire in my example would have 53 turns properly spaced and centered with an inductance of about 320 uH, having a 27pF value at 1710kHz. Commonly, #22 wire is 59 turns with 400uH inductance. I wanted to keep the example building, so the reader gets a sense of how the formula-parts fit together.

Paul S. in CT

--- In ultralightdx@..., "jim_kr1s" <jkearman@...> wrote:



--- In ultralightdx@..., "ferrite61" <dxrx@> wrote:

1.855 * 47.2 * 75^2 * 0.79375^2 / 25.33 * 19.05 = 310295.8 / 482.55365 = 643uH
Nice explanation, Paul. According to the Silicon Labs datasheet, the inductance should be between 180 and 450 uH (Si4730/31-C40, page 21). The current batch of chips may tune a 554-uH (or even perhaps 643-uH) inductor at 1710 kHz, but there's no guarantee the next batch will. Your suggestions re turns spacing and Litz wire mirror what I said in a previous post, based on work done by Ben Tongue. Using that information to build antennas that fall within SiLabs' recommendations is the best approach.

73,

Jim, KR1S


Re: Loopstick coil winding findings

jim_kr1s <jkearman@...>
 

--- In ultralightdx@..., "ferrite61" <dxrx@...> wrote:

1.855 * 47.2 * 75^2 * 0.79375^2 / 25.33 * 19.05 = 310295.8 / 482.55365 = 643uH
Nice explanation, Paul. According to the Silicon Labs datasheet, the inductance should be between 180 and 450 uH (Si4730/31-C40, page 21). The current batch of chips may tune a 554-uH (or even perhaps 643-uH) inductor at 1710 kHz, but there's no guarantee the next batch will. Your suggestions re turns spacing and Litz wire mirror what I said in a previous post, based on work done by Ben Tongue. Using that information to build antennas that fall within SiLabs' recommendations is the best approach.

73,

Jim, KR1S


Re: Loopstick coil winding findings

ferrite61 <dxrx@...>
 

I am posting responses to this msg based upon experiences and knowledge gained. In some cases there are no hard-and-fast rules, but significant differences are observed.

--- In ultralightdx@..., "Roy" <roy.dyball@...> wrote:


Hi All

After having wound about 20 coils in different combinations of Litz and
wire wrap wire (silver plated oxygen free copper low conductivity Kynar
covered) wire. Wound in a normal manner, spaced, and segmented. I have
come to the following preliminary conclusion for the 4.00 X 3/8 inch
unknown ferrite rod I have been using.
4" x 3/8" is a 10.7 length to diameter ratio that is generally sufficient for good nulling. Generrally, 8 to 1 or better is needed for any kind of good nulling.

There is little or no difference between the 30AWG wire wrap wire and
40/44 Litz. The results just mirrored wether spaced or normal windings.
Yes, this is very true, as noted in Crystal set learning years back, the litz effect on the AM-BCB doesn't really take hold until comparing #22 AWG to 270/46 litz. For wire diameters under #22 AWG solid wire is just as effective and much cheaper.

In all ferrite-rod coils one must space the windings such that the space is equal to the wire diameter. This reduces the "proximity effect" between turns of wrapping. For litz wire especially, one must use the "bundle diameter" NOT the outer jacket diameter. Magnet wire has a very thin insulation, and can be generally ignored except when using #28 or higher gauge (#30, #32, etc). Here, the solid wire diameter is used (#28 = 0.0125", #30 = 0.01", #32 wire = 0.008")


The best results were obtained using single wire spacing with a coil
former, in my case Teflon tape. I chose the Teflon because of its
excellent dielectric and insulating properties.
I have also noted that heat-shrink tubing is acceptable: its an open weave type of plastic similar to HDPE, which is also an excellent insulator. Thickness of each wall is 0.025" adding 0.05" to the ferrite rod diameter. One could go 2 layers with good results.

I noticed with the coil former the signal strength was higher above
1200Khz and stayed that way to the end of the band (1710).
Believe it or not, that is what should happen with small diameter-low count litz. The acceptable frequency range increases higher. For solid wire, the effect is lesser, depending upon the gauge: higher gauge # shows a little more effect than lower gauge #.

What I ended up with is a G8 when sitting side by side a stock standard
PL-310 set at 3Khz bandwidth. Having an increase of 1-2 dbu up to
1200Khz then 2-4 dbu to the end of the band with similar S/N readings.

It was quite surprising to find the lengths of wire between the Litz and
the Kynar were almost the same to resonate the coil. I also found my
best coils were when the Si4734 reported a capacitance value around 24pf
when tuned to 1710Khz. I recommend modifying your unused G8's with
the USB interface even if it is only to get the capacitance values for
loopstick tinkering. Why not let the radio tell you what's going on
instead of dozens of assumptions that may be incorrect. Scott is also
producing a USB interface but may not be able to share the software, but
in either case once you have learnt how to make the modification it will
be simple to slot any board in place. It is only four wires.

Cheers Roy.

Thanks for this Roy: I will also add the following helpful things important to ferrite stick construction. One can design a stick using this to close approximation.


1) Center the windings: keep them as far away from the ends as possible.
2) Space the turns 1 to 1 meaning the space between turns is the same as the COPPER wire diameter.
3) The length of the coil itself should be between 35% and 40% of the ferrite rod length to reinforce suggestion #1 above. This will optimally maximize the Q and the inductance increase.
4) Therefore some important numbers are needed in designing a ferrite-rod inductor.
a) The copper wire diameter of the gauge used.
b) The length and diameter of the ferrite rod.
c) The length of the coil as prescribed. 40% of rod length is quite good. (3" per 7.5" rod)
d) The number of turns allowed by maximizing the properties of the coil. For 3" of coil length one will wrap 1/2 of the turns provided by dividing the 3" length by the wire diameter. {Example: 3/0.01 x 0.5 = 150 turns of #30, and 3/0.02 x 0.5 = 75 turns of #24}
e) The area of the ferrite rod X-section usually in the shape of an "O" = pi* (1/2diam)^2
f) A very good approximation for the properties of the #61 Amidon rod. The rule of Thumb thats very accurate is to start with a length to diameter ratio of 4 being a factor of 16. For each unit increase, add 3.9. {Example: at 8 to 1 this factor is 31.6, at 12 to 1 its 47.2}
g) A very good approximation that deals with the coil length being shorter than the rod length. This factor is refered to as the "K factor" in various ferrite literature. I have never seen an "absolute" formula.

Tuff math here no matter what... Best method accurate to 1% is as follows;
Let R = length of rod / length of coil ( for 7.5" and 3" respective this is 2.5 )

R^(1/R^0.43) Using the example 2.5^(0.4^0.43) = 2.5^0.67435 = 1.855 So we have approximated K as 1.855 when the coil is centered, spaced 1 to 1, and is 40% of the rod length.

h) An approximation of the Ue of the ferrite inductor becomes the factor in step f x K. In the ongoing example this is 47.2 x 1.855 or a Ue of about 87.556 when the rod is 12 times longer than its diameter, and the coil is 40% of the rod length and centered.

i) We will need to consolidate some universal constants to make a rather simple inductance formula. The U0 (U sub zero) is defined as 4x pi x 10E-7 nH/cm, and there are 10000 Maxwells per Gauss of attraction: also pi from the determination of the X-section of the rod is consolidated. These three multiply as 0.03948

We are now ready to form an equation that will closely approximate the ideal inductance (at low frequencies) of a ferrite rod wound to near ideal conditions of centering, wire-spacing and distance-to-end.

K * factor * N^2 * r^2 / length of rod * 25.33

N^2 is the square of the number of turns
r^2 is the square of the radius of the ferrite rod
25.33 is the constants in step i placed in the denominator (1/0.039478)

ALL measurements are in centimeters, since everything else is derived from the Metric System.

For our example lets make the ferrite rod 5/8" diameter and 7.5" long for a ratio of 12 to 1.
We will use #24 wire (0.02") for 75 turns in 3" length. The 5/8"diameter is 1.5875 cm: the radius is therefore 0.79375. The 7.5" length of the rod is 19.05cm. The final answer will be in microHenries of inductance (uH)


1.855 * 47.2 * 75^2 * 0.79375^2 / 25.33 * 19.05 = 310295.8 / 482.55365 = 643uH

Note that if one tests the inductor at AM-BCB frequencies, the inductance will appear to increase. This is due to some losses of the rod (notably hysteresis), and can't be avoided. Un wrapping a turn or two usually helps.

Paul S. in CT


Re: AM ac Coupling capacitor.

jim_kr1s <jkearman@...>
 

Roy,

Excellent! Many thanks. Then we can confidently work within the datasheet parameters for inductance.

Your results compare well with Ben Tongue's research into ferrite-bar antennas, here: http://www.bentongue.com/xtalset/29MxQFL/29MxQFL.html Using an insulating tube between the bar and the winding always requires a compromise in Q between the high and low ends of the band. A 1/16" thickness looks fair, for Litz wire.

Dielectric properties of the spacing material are less critical at MW and LW, but Teflon tape is a good choice. It's possible to buy sheet Teflon, but it's expensive and stiff. It would be hard to bend around a small circumference.

For solid wire, though, Tongue recommends not using a spacer at all, but winding directly onto the core. Ferrite rods are non-conductive; the ferrite is suspended in clay. You can prove that with an ohmmeter. So you can wind magnet or wirewrap wire directly on the rod. The rods are somewhat abrasive, so winding and rewinding could chafe the insulation, possibly causing short circuits between turns. I'm getting pretty decent Q from coils using 22-gauge solid hookup wire wound directly on a 7.5-inch -61 rod. The insulation spaces the turns, and also spaces the winding slightly off the core.

IMO, what's really helping your coils is the turns spacing, which improves Q. This is something else Tongue discusses. While you're unable to discern a difference between solid- and Litz-wire coils, the advantage may come in better front-end selectivity, which is hard to quantify due to that bloody soft mute. But it can't hurt. See pages 3 and 4 of Tongue's paper.

For internally mounted antennas, it might be worth trying thinner cores, so the antenna is a little farther from the circuit board. Any slight Q advantage obtained from a thicker core might be more than offset by proximity to the board. Inductors don't like conductive objects in their fields.

For those who may be interested in some resonant-circuit theory (it's only algebra!), see http://www.allaboutcircuits.com/vol_2/chpt_6/6.html The reason Q is important has to do with what happens in a resonant circuit, like the one formed by the ferrite-rod antenna and the internal tuning varactor.

A tuned circuit works like a flywheel. If you flip your bicycle upside-down and spin the front wheel, each time you push against it you are adding a pulse, like a radio wave does to a tuned circuit. If the bearings are well-lubricated, you can make that wheel spin really fast with very little effort. If the bearings are dirty or the brake shoes are dragging, it takes much more effort (signal level) to get the wheel turning at the same speed (speaker level).

The dirty bearings or brakes are resistance; in a tuned circuit, resistance has the effect of reducing Q. There are several techniques to improve circuit Q. Think of them as improving the bike wheel's aerodynamics. Maybe you've seen racing bikes in which the spokes are shrouded by lightweight panels to reduce wind resistance. Or you could use thinner tires. Better bike "Q" wins races; better radio Q makes signals easier to copy.

73,

Jim, KR1S


ULR Loggings

Jim <va3jno@...>
 

I am in Kirkland Lake Ontario for a few days, so I have some time to increase my totals from that location.

Radio Used.......................................barefoot Sony SRF-59
Total ULR Loggings (Kirkland Lake)...............154

1690 WPTX Lexington MD. "WPTX AM Lexington" at 1900 EST Jan 9, then into news. Very poor, in and out. 10kW/1kW.

1670 CJEU Gatineau QC. Young girl interviewing a woman in French. "Ici La Radio Enfant" at 1910 EST Jan 9. Very poor, fading up and down. 1kW.

1690 CJLO Montreal QC. Rap and hiphop music. Two men discussing the music being played at a club in Montreal. "16-90 CJLO" at 1936 EST Jan 9. Fair to poor. 1kW.

1690 WVON Berwyn IL. "The Talk of Chicago" at 1938 EST Jan 9. Very poor, in and out. 10kW/1kW.

1690 CHTO Toronto ON. "Good evening and welcome to the Greek Canadian Hour on CHTO" and "You are listening to the Greek Canadian Hour on CHTO AM 16-90" at 2011 and 2013 EST Jan 9, then into Greek music. Good momentarily, but generally very poor. 1kW.

1660 WQLR Kalamazoo MI. Fox Sports Radio. Two men discussing next week's New York Jets vs Indianapolis Colts football game, and the head coaching job at Buffalo. "16-60 The Fan" at 2028 EST Jan 9. Poor to very poor and mixing with others. 10kW/1kW.

1660 WWRU Jersey City NJ. In Korean, then "16-60 WWRU Jersey City" at 2100 EST Jan 9, and back into Korean. Good for ID but generally very poor. 10kW/1kW.

1670 WDTY Madison WI. On The House, a home fix-it show with 2 men and a woman taking calls, but mostly talking amongst themselves. Ads, then a promo for the morning show "on Madison 16-70 WDTY" at 0651 EST Jan 10. Poor and over CJEU. 10kW/1kw.

1610 CHHA Toronto ON. Gospel and reggae gospel music. "CHHA Radio ..." in English at 0742 EST Jan 10. Very poor and mixing with a French station. 10kW/1kW.

Jim Orcheson
DXing in Kirkland Lake, Ontario


AM ac Coupling capacitor.

Roy <roy.dyball@...>
 

Hi Jim

Unfortunately my capacitance meter has decided not to work. I traced the coupling capacitor with a meter right to pin 4 on the Si4734 and have highlighted it in the diagram below with arrows. It is marked as 105 which is 10 with 5 zeros pf, being 1 microfarad. This makes sense as the evaluation board has a 0.47µf for the AM and a 0.47µf for the SW paralleled on pin 4.

With the G8 both SW and MW have already been combined thus keeping the coupling capacitance similar.

Roy.


Re: Loopstick coil winding findings

jim_kr1s <jkearman@...>
 

--- In ultralightdx@..., "Roy" <roy.dyball@...> wrote:

I also found my best coils were when the Si4734 reported a capacitance value around 24pf when tuned to 1710Khz.
That works out to an inductance of about 361 uH. Your finding that spacing the coil slightly above the core, and spacing the windings by the widt of the wire, correlates with prior experiments on ferrite-rod inductors.

Roy, can you connect a C meter from the chip's AM port (AMI?) to the hot connection to the inductor, and see what they used for a series cap? Or is the chip covered by a shield as in the PL-380?

73,

Jim, KR1S


Loopstick coil winding findings

Roy <roy.dyball@...>
 

Hi All

After having wound about 20 coils in different combinations of Litz and wire wrap wire (silver plated oxygen free copper low conductivity Kynar covered) wire. Wound in a normal manner, spaced, and segmented. I have come to the following preliminary conclusion for the 4.00 X 3/8 inch unknown ferrite rod I have been using.

There is little or no difference between the 30AWG wire wrap wire and 40/44 Litz. The results just mirrored wether spaced or normal windings.

The best results were obtained using single wire spacing with a coil former, in my case Teflon tape. I chose the Teflon because of its excellent dielectric and insulating properties.

 I noticed with the coil former the signal strength was higher above 1200Khz and stayed that way to the end of the band (1710).

What I ended up with is a G8 when sitting side by side a stock standard PL-310 set at 3Khz bandwidth. Having an increase of 1-2 dbu up to 1200Khz then 2-4 dbu to the end of the band with similar S/N readings.

It was quite surprising to find the lengths of wire between the Litz and the Kynar were almost the same to resonate the coil. I also found my best coils were when the Si4734 reported a capacitance value around 24pf when tuned to 1710Khz. I recommend modifying your unused G8's with the USB interface even if it is only to get the capacitance values for loopstick tinkering. Why not let the radio tell you what's going on instead of dozens of assumptions that may be incorrect. Scott is also producing a USB interface but may not be able to share the software, but in either case once you have learnt how to make the modification it will be simple to slot any board in place. It is only four wires.  

Cheers Roy.


ULR DX.......One NEW STATION @ SUNSET.........1330 WPJS Conway, SC

robert ross
 

Hi Guys:

One New Station for both the ULR and OVERALL LOGS tonight at SUNSET.

Gradually sneaking up on ULR # 800...but Man this is getting harder with every new one logged!! Setting my sights on # 800 by the end of the month!! Hopefully.......

Radio Used.........SONY SRF-T615 ULR BAREFOOT
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

ULR LOG TOTALS are now.....789 Stations Heard
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

73....ROB

Robert S. Ross VA3SW
London, Ontario CANADA

********************************************************************
1330 WPJS Conway SOUTH CAROLINA Jan/09/10 1621 EST EE FAIR
Public Service Announcement for "Seaside Vacations in North Myrtle
Beach a a Local ??? Hospital sponsoring an event" @ 1621 EST.
Into Black Gospel Music @ 1622-24 Fade Out.

NEW STN ULR # 789 3.2 KW/23 Watts Nights
ROSS, ONT.
*********************************************************************


Second PL-380 Model Receives 7.5" Loopstick Transplant

Gary DeBock
 

Hello All,
 
Thanks to those who have expressed interest in the experimentation to improve the loopsticks in the Tecsun PL-310 and PL-380 models (and special thanks to those who are participating in the experimentation).
 
Following the procedures detailed in the PL-380 7.5" External Loopstick Modification article posted in the Ultralightdx file section (under modifications), in the Dxer.Ca ULR file section (under modifications), and linked at  http://www.mediafire.com/?hudn0mtlueg , a 7.5" loopstick composed of an Amidon type 61 ferrite bar and an 81-turn 40/44 Litz wire coil has been transplanted into another PL-380 model, providing the same great AM and LW sensitivity boosts obtained in the first transplant model. Using an 81-turn Slider coil on the ferrite bar to find the optimum coil inductance for peak AM sensitivity, detailed tests were run at both 530 kHz and 1660 kHz, both of which indicated a clear peak in AM sensitivity with a coil inductance of 554 uh (the same optimal inductance value found in the first PL-380 transplant model).
 
The first 7.5" loopstick transplant model has already proven quite effective in TP-DXing here, and hopefully other hobbyists will feel motivated to build their own highly sensitive PL-380 models, to augment the outstanding 1 kHz selectivity provided by the Si4734 DSP chips.
 
73, Gary DeBock (in Puyallup, WA, USA)   
 
                                                                 
,


Re: LC inductance / capacitance Meter (WARNING)

Horacio Nigro <hanigrodx@...>
 

Many thanks for the warning!
 
                          
   Horacio A. Nigro

    Montevideo     
    Uruguay


 






De: sdwillingham
Para: ultralightdx@...
Enviado: sáb,9 enero, 2010 21:19
Asunto: [ultralightdx] Re: LC inductance / capacitance Meter (WARNING)

 


Looks like a very nice design. Thanks.

However, **WARNING**: the web store that sells kits for this meter started installing stuff in the background on my computer! Google-Chrome warned me the site might be dangerous and I ignored it. A little while later Windows Defender popped-up with more warnings. When I investigated, several suspicious processes were running on my computer!

I think the page that Horacio links is safe, but watch out if you try to buy a kit!

-Scott-

--- In ultralightdx@ yahoogroups. com, Horacio Nigro wrote:
>
> Those guys guilding coils for ferrite antennas ... I found this circuit and construction details for Very Accurate LC Meter based on PIC16F84A IC
>
> on http://electronics- diy.com/lc_ meter.php
>
>
>
> Horacio A. Nigro
> Montevideo
> Uruguay
>



Re: LC inductance / capacitance Meter (WARNING)

sdwillingham
 

Looks like a very nice design. Thanks.

However, **WARNING**: the web store that sells kits for this meter started installing stuff in the background on my computer! Google-Chrome warned me the site might be dangerous and I ignored it. A little while later Windows Defender popped-up with more warnings. When I investigated, several suspicious processes were running on my computer!

I think the page that Horacio links is safe, but watch out if you try to buy a kit!

-Scott-

--- In ultralightdx@..., Horacio Nigro <hanigrodx@...> wrote:

Those guys guilding coils for ferrite antennas ... I found this circuit and construction details for Very Accurate LC Meter based on PIC16F84A IC

on http://electronics-diy.com/lc_meter.php



Horacio A. Nigro
Montevideo
Uruguay


Re: Delay in Ferrite Bar Shipments from Amidon

Gary DeBock
 

Hello Farmerik,
 
Thanks for your generous comments, and of course I do enjoy tinkering with Ultralight radios-- especially by giving them far more effective loopsticks.
 
The Amidon ferrite bar shipment actually arrived out of the blue today, with no notice from Amidon that it had even been shipped. So there finally may be some experimentation here to try making new internal loopsticks for the PL-310 and PL-380 (along with several other guys).
 
73 and Good DX, Gary  
 
In a message dated 1/8/2010 7:58:27 P.M. Pacific Standard Time, farmerik@... writes:

 

You are just ordering them faster than they can make them!

I was searching on line and on eBay, and it looks like there are a bunch of new models of radios with DSP in there description sold under different names, including kacheapo. Your work may be piling up!

Thanks for your tireless efforts, and all the other experts here working on improving these superb little radios. You know what they say, hard work is always rewarded with MORE hard work! I expect you enjoy it though. - FARMERIK

--- In ultralightdx@yahoogroups.com, D1028Gary@... wrote:
>
> Hello All,
>
> Thanks to all who have shown interest in the Tecsun PL-310 and PL-380
> loopstick experimentation, to upgrade the AM (and LW) sensitivity in these
> highly selective DSP models.
>
> Those who have recently ordered ferrite bars from the Amidon Corporation
> (or who are just interested in the tinkering progress) may be interested to
> know that my ferrite bar order placed with Amidon on December 23 has not yet
> been shipped. This is unusual for Amidon, which has typically shipped
> orders out to me within a couple of days of payment.
>
> Included in my order were the shorter type 61 ferrite bars to use in
> creating an in-cabinet loopstick for the PL-310, and also two 7.5" type 33
> ferrite bars to use in a PL-380 LW-optimized loopstick experiment. As yet, no
> shipping date has been provided for this order.
>
> 73, Gary DeBock (in Puyallup, WA, USA)
>


Re: Delay in Ferrite Bar Shipments from Amidon

Roy <roy.dyball@...>
 

Gary

I ordered three rods (4.00 6.00 7.50) a day or two before Christmas. Just got conformation of shipping. I nearly fell over backward to find they have charged me $36.00 (US) to ship to Australia. Dave only charged me $6.00 to ship a bag of Litz which I have already received.

Roy.

 

--- In ultralightdx@..., "Chris Knight" wrote:
>
> Hmmm. I wonder what's up with Amidon.
>
> There is another source for Amidon ferrite rods:
> http://www.universal-radio.com/catalog/misc/amidon.html . Universal part #
> R61-050750 should do the trick. The ferrite rods being sold by Universal
> were made by Amidon. BTW, Universal Radio is also the company mentioned by
> John B. as having the radio stands. :)
>
> 73,
>
> Chris Knight (N0IJK)
> Fort Lupton, Colorado
> http://sites.google.com/site/ftluptonulrlogs/
>
> -----Original Message-----
> From: ultralightdx@... [mailto:ultralightdx@...] On
> Behalf Of D1028Gary@...
> Sent: Friday, January 08, 2010 5:50 PM
> To: ultralightdx@...
> Subject: [ultralightdx] Delay in Ferrite Bar Shipments from Amidon
>
>
>
> Hello All,
>
> Thanks to all who have shown interest in the Tecsun PL-310 and PL-380
> loopstick experimentation, to upgrade the AM (and LW) sensitivity in these
> highly selective DSP models.
>
> Those who have recently ordered ferrite bars from the Amidon Corporation (or
> who are just interested in the tinkering progress) may be interested to know
> that my ferrite bar order placed with Amidon on December 23 has not yet been
> shipped. This is unusual for Amidon, which has typically shipped orders out
> to me within a couple of days of payment.
>
> Included in my order were the shorter type 61 ferrite bars to use in
> creating an in-cabinet loopstick for the PL-310, and also two 7.5" type 33
> ferrite bars to use in a PL-380 LW-optimized loopstick experiment. As yet,
> no shipping date has been provided for this order.
>
> 73, Gary DeBock (in Puyallup, WA, USA)
>


Re: New version of Tecsun PL-380

jim_kr1s <jkearman@...>
 

--- In ultralightdx@..., Mark Roberts <markrobt@...> wrote:
I'm not going to make any modifications to these radios because I
really do plan on traveling outside the country with them, and I don't
want some TSA rent-a-cop to get all excited because he saw some wires
sticking out of an electronic device.
Just stick a Fruit-of-the-Loom sticker on it. They won't suspect a thing. :)

73,

Jim, KR1S


Re: New version of Tecsun PL-380

Mark Roberts
 

On Sat, Jan 9, 2010 at 1:35 AM, sdwillingham <sdwillingham@...> wrote:

That is correct (assuming G8 = PL-300).  I've been able to read out the bandwidth parameter on my PL-300 using an experimental USB interface.
I ran some plots this morning and it's pretty clear that it's 3 kHz.
(I plan to upload them later today.)

The 6 kHz position on the PL-380 seems to be more like 5.5 kHz. It's
possible there is some limitation in the source material. But I have
been using KFRC because it does not have IBOC and doesn't appear to
have applied the 5 kHz bandwidth restriction recommended for IBOC
usage.

I'm not going to make any modifications to these radios because I
really do plan on traveling outside the country with them, and I don't
want some TSA rent-a-cop to get all excited because he saw some wires
sticking out of an electronic device.


Re: Latest DX - Friday 08 Jan 2010

Stephen Ponder <n5wbi@...>
 

Thanks, Chris! It was a real surprise! I'm happy to be
able to add them as a new country to my ULR log!

73 & God bless,

Steve N5WNI
Clear Lake City TX

Very nice reception, Steve!

It would be almost impossible here as I now have a local
on 810 (KLVZ) which used to be on 800. Their move freed up
800 enough to pull in CKLW last week > on a PL-380. Still,
I'd rather have Bahamas for a new country.

73, Chris


Chris Knight (N0IJK)
Fort Lupton, Colorado
http://sites.google.com/site/ftluptonulrlogs/