Bob W7AVK <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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An additional item about the TR-7 AF/RF/Power switch combination. The
control was a special order by DRAKE 30 years ago and is one of those
"unavailable" replacement parts today. Its only a matter of time before
the on/off power switch fails because of the type of service its doing.
If you don't want to rebuilt the control with a new switch assembly
found somewhere else I might suggest using an external power strip and
switch to control the TR-7 AC power.
Just my $0.02.
Good Luck
73 Bob W7AVK
Home of the TR-7 Extender Boards
Floyd Sense wrote:
"Floyd Sense" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Makes sense. I have around 60 high-end BC/SW radios from the late 1930s
and most of them have the on/off switch on a control other than the
volume control (tone control for example). Anyway, I feed my audio
through an external DSP unit which is used to control the volume and can
run it down to zero that way.
73, Floyd - K8AC
----- Original Message ----- From: "Garey Barrell" <[EMAIL PROTECTED]>
To: "Floyd Sense" <[EMAIL PROTECTED]>
Cc: "drake" <[email protected]>
Sent: Tuesday, November 01, 2005 10:44 PM
Subject: Re: [drakelist] TR7 AF gain control
Floyd -
Well, a lot of answers, but no one seems to have come up with the
"real" reason the AF gain on the TR-7 doesn't turn the audio
completely off.
No big plot to prevent the ops from turning the audio down
"accidently" so they can sleep, no quirk of solid state, or any of the
other reasons that have appeared over the years.
The reason, plain and simple, is that the ON-OFF switch mechanism has
to have travel room to operate the switch. Result? You can't turn
the pot all the way to zero without turning the radio OFF! Any radio
that has the On-Off switch on the AF Gain control has the same
problem, depending upon how much AF gain is after the volume
control. This is why most receivers/transceivers have the power
switch on a Function switch, or sometimes on the RF Gain control.
Easiest way to kill the audio is to back off on the RF Gain control by
grabbing both concentric knobs together as you turn it down.
When the unobtainium AC power switch on the TR-7 dies, (which they all
do if you use them enough,) and you wire across it and use an external
power strip or other external switch, (like you shoulda been doing all
along,) THEN you will be able to turn the AF Gain all the way down.
If that "click" at the end bothers you, you can take out the switch
actuator!
73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual
<http://www.k4oah.com>
.
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