[Lowfer] DPC on air

Tue, 24 Feb 2004 22:41:52 -0500

Mike,

The setup is nothing too elaborate. Loop conductor is RG-8 size orange
Ethernet coax which has a double shield/double foil and solid center
conductor. All conductors are soldered together at both ends. I have a 1000'
spool of this stuff which I use for HF and the Teflon outer jacket makes
hoisting it through tree branches very easy . Basically, the coax is closely
matched to Belden 9913. The overall loop is approximately 50'x50' and is
positioned about 6' off the ground. The choice of trees I have in the back
woods only allows me to orient the loop N/S. Not the best, but at least its
a start for a newbie.

The loop TX final is a modified complimentary "Ashlock" pair using the
MPS6602/6652 transistors. Tank circuit is a stack of 500V silver micas
totaling 8700 pF along with a 500 pF compression trimmer in series with the
loop to bring into resonance with the aid of a screwdriver. When moving up
the band into the 185.3 range, I reduce the capacitor bank by 1000 pF to
obtain resonance. At last, the TX final is coupled via a 14:1 toroidal
transformer wound on a 1" diameter x1/2"  'J' type ferrite core generously
donated by Bill A. himself (very much appreciated!). Additional "stuff"
includes a 100 turn CT to measure antenna current locally or back in the
shack some 125' away. All components are mounted in a weather tight PVC
enclosure mounted to a tree. Dex's website has a couple of photos in the
Lowfer gallery, you can't miss the loop conductor.

In the beginning, I was using an Epson oscillator chip as my exciter and
keying it via RS-232, but now have a working ZL1BPU DDS exciter on a
breadboard using the ATMEL AT90S2313 chip. I'll eventually transfer the
components to a PC board once the Lowfer season quiets down.

Denis

----- Original Message ----- 
From: "WE0H" <[email protected]>
To: <[email protected]>
Sent: Tuesday, February 24, 2004 9:47 PM
Subject: RE: [Lowfer] DPC on air

> Hey Denis,
>
> What are you running for a loop conductor and loop tuner parts?
>
> Thanks
> Mike>WE0H
>
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]]
> On Behalf Of Denis Cote
> Sent: Tuesday, February 24, 2004 7:09 PM
> To: [email protected]
> Subject: Re: [Lowfer] DPC on air
>
>
> Thanks for the report Bill. I'll be changing modes a bit more often now
that
> the DDS exciter is working well. After switching frequencies and adjusting
> the tank ckt Sunday, I measured approximately 1.13 A antenna current. I
bit
> low compared to the 1.5A back in January but the temps here are in the
high
> 30's and the ground is thawed a bit.
>
> Denis
>
>
> ----- Original Message -----
> From: "Bill Ashlock" <ashlockw@ >
> To: <[email protected]>
> Sent: Tuesday, February 24, 2004 6:16 PM
> Subject: RE: [Lowfer] DPC on air
>
>
> > >Lowfer beacon 'DPC' is now actively transmitting QRSS-30 on 173.500 KHz
> via
> > >DDS exciter. Modes >are subject to change.
> >
> > Lookin good at 173.500 Denis!  About 4 uv/m on the SVM.
> >
> > Bill
> >
>
>
>
> _______________________________________________
> From the Lowfer mailing list
> Send messages to: [email protected]
> To sub/unsub visit: http://mailman.qth.net/mailman/listinfo/lowfer