Garey (and also Don who suggested the same),
I pulled the bottom cover and checked the 10R and 10T lines. They are
working correctly. I measured 9.9V on the 10R line in receive and 0.00 in
transmit. I measured 0.0V on 10T in receive and 9.9V in transmit.
Any other suggestions?
Dave
----- Original Message -----
From: "Garey Barrell" <[email protected]>
To: "Drakelist" <[email protected]>
Sent: Thursday, December 11, 2008 4:21 AM
Subject: Re: [Drakelist] TR-7 Question
Dave -
T/R problems are often associated with the 10R and 10T control lines and
their "fuses", Q306 and Q307.
Check both busses, marked on the parent board traces. Each must be very
close to +10 when receiving or transmitting respectively AND very close to
0V inversely. You'll probably find that the 10R bus does NOT go to zero
in transmit as it should.
Q306 and Q307 are on the Transmit Exciter board. If you don't have a
Service Manual, you'll need help finding them.
Let us know.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
[email protected] wrote:
Hi Gents,
I recently acquired my first TR-7 (thank you Evan K9SQG for sharing and
thank you Gary W8PU for some technical guidance in finding a shorted pin
diode). When I transmit on phone, I'm getting some garbled audio fed
back into both the headphones and the external speaker connected via the
rear panel. It's very distracting and makes it difficult to talk
normally. Audio reports from distant stations say my transmitted audio
(Shure 444D) is fine. I'm using a Steppir 2L, so I don't have a bunch
of RF running around the shack and the mic gain is set to just kick the
ALC in on peaks. The garbled audio is also present transmitting into a
dummy load. I'm using an Astron 35A power supply.
Using the same exact set-up (coax cable, speaker, speaker connection
cable, power supply, etc.) with my Tentec Orion, it's perfectly clean.
Any thoughts/suggestions?
73,
Dave / K8JDC
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