Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick
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.comtoggle quoted messageShow 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.