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[TenTec] Orion TX problem fixed

To: tentec@contesting.com,"Mike McAmis W1ECT" <michael.mcamis@valley.net>,"Bill Hein NT1Y" <Bill@AA6TT.com>, "Willard Myers" <Bill@K1GQ.mv.com>
Subject: [TenTec] Orion TX problem fixed
From: "Dick Green" <dick.green@valley.net>
Reply-to: dick.green@valley.net, tentec@contesting.com
Date: Sat, 10 Jan 2004 16:44:05 -0500
List-post: <mailto:tentec@contesting.com>
A while back I posted a message reporting that my Orion had a serious TX
problem. The transmitter had been fine for 1020 Qs on ARRL SS CW and 3066 Qs
in CQ WW CW, but after one QSO in ARRL 160 the power dropped to 50% while
the ALC light blinked wildly. I sent the rig to Ten Tec right away. They
fixed it promptly, but I asked them to hold it over the holidays since I
wasn't here to receive the package.
I'm pleased to report that my Orion is back and the TX is operating fine
now. The service report indicates that Q21 on the Antenna Switch board was
replaced. There is no schematic labeled "Antenna Switch Board", but it
appears that the schematics labeled "Input/Output A0" refer to this area. I
found Q21 on drawing 3 of 5, and it appears to be part of a circuit that
samples RF at the antenna connectors. The signal chain ends with a little
flag labeled "R". I found a matching flag on -- no surprise -- the schematic
for the ALC circuitry. I would guess that the transistor in question is part
of the ALC feedback loop, and the symptoms I had certainly would support
This might have been a random component failure, but it occurs to me that
the antenna switch board is probably close to the antenna connectors at the
rear of the chassis, where there is a line of vent slots across the back of
the top cover. I had a (no longer available) WX0B switchable bandpass filter
sitting on top of the Orion in that spot. It had feet that raised the filter
maybe 1/3 of an inch above the Orion, but the filter case is almost exactly
as long as the Orion is wide, so it was above all of the slots. It's
conceivable that this arrangement prevented adequate ventilation, especially
during the heavy TX duty cycle while CQing in CQ WW CW, and that this caused
premature failure of Q21. Of course, I'll never know.
I've rearranged the operating desk and moved the filter elsewhere. I still
have a meter and switch box (both with feet) on top of the Orion, but they
are in the middle of the top cover, between the two sets of vent slots
(i.e., no vent slots are covered, just the speaker that I rarely use.)
I was very pleased with Ten Tec's very rapid response. They also updated the
RF Conversion and Power Distribution Boards, as well as the firmware to
I updated the firmware to 1.367 when the rig returned. I encountered tw
audio-related problems. First, the Binaural RX did not work until I did a
master reset. Second, I left the radio idling for about an hour and when I
returned there was no audio from the Main RX. The digital S-meter indicated
signals, but no amount of fooling around would get audio out of the Main RX.
The Sub was fine. I power cycled the Orion and the audio came back. Judging
from some recent posts, I may have stumbled on the magic sequence with
Binaural RX that kills the audio.
At any rate, I'm delighted to have my Orion back and working well.
73, Dick WC1M
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