[ct-user] CT keying problems solved

Larry Johnson Larry Johnson" <k5yf@wt.net
Fri, 26 Dec 1997 01:22:54 -0000

Recently I posted a problem I was having with CT keying. That problem has
now been resolved, and I'm posting this info for the benefit of anyone else
who might encounter this problem. The credit for identifying the real
problem and the solution goes to Fred Hopengarten K1VR. He's the one who
suggested what the problem might be, patiently persisted in explaining it,
and he was right on nose. Also, thanks to Ken K1EA for his ideas and help.

The symptoms were the keying would fade out when sending with CT during
those brief seconds of transmission by the 2m rig on the DX cluster,
resulting in dropped CW dits and dahs. The problem happened even when
transmitting HF into a dummy, The problem got better if I decreased the 2m
pwr to med and then low pwr, but didn't go away completely. For a while, I
was convinced the problem was 2m RFI related. However, that wasn't the

The problem was due to the 12vdc pwr supply I was using for 2m rig. More
specifically, the problem was due to the pwr supply not being quite enough.
I also had the TNC and a Timewave DSP-9 on the same 12v pwr supply, which I
believe is an 11a supply. I moved the 2m rig to it's own 25a regulated 12vdc
supply, and all of the keying problems went away.

It turns out the 2m rig is drawing 12a when transmitting, although it (and
everything else) seemed to work fine on the 11a supply. In trying to analyze
why I never had this problem until recently, I can only come up with one
viewpoint, again thanks to Fred. Although I have multiple 120 lines (plus a
240 line) to the shack, the overall load in the shack has increased over the
last couple of months beyond what it used to be. For example, I've added
additional lights around the operating positions that I didn't have before.
When transmitting, the total load degraded the 110 just a bit, in turn
degrading the 12vdc supply just enough to affect things. Now, moving the 2m
rig to it's own stiffer supply resolved that issue.

So, if you have a similar problem in the future, this is another alternative
to consider. My problem is resolved and believe me, I'm very grateful
(thanks Fred). Best wishes to all of you and yours for the holiday season
and the New Year. CU on the air and CU in the 'tests. GL es 73 de Larry.

Larry Johnson, K5YF
Houston, TX
e-mail: k5yf@wt.net

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