[Lowfer] WM and MP post dinner shot
rick kirby
theumpire at verizon.net
Thu Jan 28 23:07:29 EST 2010
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
----- 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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