Brings back several memories. First of all I just picked up a DX-60B which
was the first transmitter kit that I built. Actually mine was an A model.
Guess I'll check out Doug's link.
But the other was the constant adjustment. Started RTTY Contesting with my
old buddy, Hal, WA7EGA, and he had this old pair of Kenwood Twins that he
FSK'd with the feed through cap to the VFO tube as well.
We were banging away on the old keyboard and the phone rang, Since I was
logging on the Atari computer for Hal, I picked it up. The voice on the
line said, is Mr. Howard Blegen available. I said back no not really we are
doing a contest. He then identified himself as the FCC monitoring station.
I quickly handed Hal the phone and said, "Hal the FCC is on the line". Hal
figured it was a neighbor as he lit up lights all over his neighborhood and
was quite famous. The FCC guy sez are you transmitting. Hal said yes we
are. 14.088.0 with exactly a 170 Hz shift (we set it with the frequency
counter several times a contest). The guy tuned up there and so oh, yes you
are...on 14.088.0 and the shift looks good, the problem is that you are also
on 13.99x.xx and that is Air Force Transcon net and you are blocking them.
What are you using for an AMP? Hal explained about the fine of ThunderBolt
that we used in early contests. Guy said well shut it down. Which we
did. That was SARTG of 198? can't quite remember and those Kenwood Twins
were sold at the September Spokane Hamfest for a quite cheap price and Hal
then went to the ICOM 751 which we both ran for several years.
So much for FSKing some old rigs!
Jay WS7I
On Tue, Aug 23, 2011 at 5:09 PM, Doug Hall <k4dsp.doug@gmail.com> wrote:
> There is a chapter in my Hallicrafters HT-37 manual entitled "Notes on
> RTTY Operation of the HT-37 Transmitter/Exciter." This transmitter
> (and some others of its day) had a feedthrough cap going to the
> cathode of the VFO tube. By diode switching a trimmer in and out of
> the circuit you could shift the frequency by an amount determined by
> the trimmer setting. I can't imagine using such a beast - between the
> VFO drift and the temp/mechanical effects on the trimmer it would
> likely require frequent adjustment.
>
> When I redesigned the VFO for my Heathkit DX-60B
> (http://k4dsp.homeip.net/~doug/HG-10D/HG-10D.html) I used a DDS chip
> and made provision in the firmware for FSK. Unless somebody claims
> otherwise I claim to be the only person to ever operate RTTY using a
> DX-60B. One of my more dubious achievements.
>
>
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