[Lowfer] WM and MP post dinner shot
Bill Ashlock
ashlockw at hotmail.com
Fri Jan 29 02:06:05 EST 2010
Rick,
So you are very close to my predicted 8 to 1 ratio for #12 loop conductor, right? (24 divided by 3 = 8) If you were using a type 77 core you would find that there is enough inductive reactance to use only 8T on the primary and 1T on the secondary.
QED
Bill
> From: theumpire at verizon.net
> To: lowfer at mailman.qth.net
> Date: Fri, 29 Jan 2010 04:07:29 +0000
> Subject: Re: [Lowfer] WM and MP post dinner shot
>
> Ok Bill,
> I am actually using 24 turns not 20 .The secondary is 3 turns.I measure
> just about 20 volts at the transmitter under keydown and a current of 50ma
> when I peak the trimmer cap.
> The loop is 200 ft but measures 40 x 60 .Its #12 wire.
> I originally wound the xfrmr with 13 : 2 ratio but the input current was
> over 100ma at resonance so I just kept adding turns to get it down to the 1
> watt level.
>
> Thanks
> Rick
>
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>
> ----- Original Message -----
> From: "Bill Ashlock" <ashlockw at hotmail.com>
> To: <lowfer at mailman.qth.net>
> Sent: Friday, January 29, 2010 3:17 AM
> Subject: Re: [Lowfer] WM and MP post dinner shot
>
>
> >
> > Hi again Rick,
> >
> > Refresh my memory a bit on what your transmitting setup is like. Assuming
> > you have only one turn on the secondary (a single pass through the core) a
> > 20 to 1 ratio is too much of an impedance ratio (400 to 1). You may be
> > using more than 24v into your final (a Vcc of 24v would represent a square
> > wave into the coupling xfmr of ~ 23v p-p) or your loop wire may be a fair
> > amount shorter than 200ft. If you were using 200 ft of #12 house wire,
> > like I am, the ratio would be close to 8 to 1. If RG-8 it would be approx
> > 13 to 1.
> >
> > You will always experience some current swing when the wind blows and your
> > loop is supported by the trees. That's because the inductance changes due
> > to the change in geometry and this takes it out of resonance. I think this
> > effect may be in the order of +/- 10% in moderate wind, so the signal
> > strength change is not all that severe.
> >
> > Bill
> >
> >> From: theumpire at verizon.net
> >> To: lowfer at mailman.qth.net
> >> Date: Fri, 29 Jan 2010 02:41:58 +0000
> >> Subject: Re: [Lowfer] WM and MP post dinner shot
> >>
> >> Great job Bill! Thats a fine signal down here in the Poconos!
> >> I just put my new transmitter on last night.I put a 7414 buffer stage in
> >> it. I was having some drifting problems under long keydowns. I also used
> >> a
> >> series regulator in the supply but I still want to replace the supply
> >> someday.
> >> I used one of the Digi-Key transformers you suggested . I found that I
> >> had
> >> to use 20 turns on the primary to get the final down to 1 watt input at
> >> resonance.
> >> Right now its very windy here . Im monitoring my signal using
> >> Spectrumlab
> >> and a downconverter. I see no frequency pulling here BUT I still notice
> >> that the final current bounces around a bit on heavy wind gusts. Do you
> >> have
> >> issues with your loops also in the wind or do I still have a problem with
> >> mine?
> >>
> >> 73
> >> Rick
> >>
> >>
> >>
> >>
> >> ----- Original Message -----
> >> From: "Bill Ashlock" <ashlockw at hotmail.com>
> >> To: <lowfer at mailman.qth.net>
> >> Sent: Thursday, January 28, 2010 4:38 AM
> >> Subject: Re: [Lowfer] WM and MP post dinner shot
> >>
> >>
> >> >
> >> > Hi Rick,
> >> >
> >> > Thank you for shutting down PBO to do some watering hole searching. For
> >> > the record, the upper, and typically stronger, of the two Wms is from
> >> > Andover, MA, and the lower is from Ellsworth, NH in the White Mountains
> >> > about 100 miles to the north. As I have said before, both stations have
> >> > identical transmitters and identical loops pointed E/W. The ground
> >> > conductivity, however in Ellsworth is much poorer than Andover's
> >> >
> >> > The next experiment will be to output more radiation from Ellsworth in
> >> > an
> >> > attempt to equalize the signals at most receiving sites by replacing
> >> > the
> >> > #12 loop wire with RG-8 of an identical length. According to my
> >> > calculations the lower loss resistance (Rac) of RG-8 should add approx
> >> > 3.6db to the signal after readjusting the turns ratio in the loop
> >> > matching
> >> > transformer so that the input power remains at 1w.
> >> >
> >> > Hope you can continue to monitor the watering hole in the future. I'll
> >> > also check out your signal from time to time.
> >> >
> >> > 73
> >> >
> >> > Bill
> >> >
> >> >> From: theumpire at verizon.net
> >> >> To: lowfer at mailman.qth.net
> >> >> Date: Thu, 28 Jan 2010 01:50:33 +0000
> >> >> Subject: [Lowfer] WM and MP post dinner shot
> >> >>
> >> >> WM and MP gettin stronger! Think conditions are going to be good
> >> >> tonight.
> >> >> Hope I get "PBO" soon !
> >> >>
> >> >> http://www.ka2pbo.com/captures/WM%20and%20MP%201-28-10.jpg
> >> >>
> >> >>
> >> >> Rick "PBO"
> >> >
> >> > ______________________________________________________________
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