[Drake] TR-7 problem

Sat, 6 Apr 2002 23:39:38 -0800

Steve...check out John's email below....this may help.
	K6XYZ

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>>>Marty:

You should check the R/T pin diodes CR1501, CR1502 and CR1503 (UM9401)
and the "calibrator" diodes CR1401 and CR1402 (MPN3404) located on the
High Pass filter.  You can buy the UM9401 pin diodes from Downeast
Microwave http://www.downeastmicrowave.com/ and the MPN3404 pin diodes
are available from many sources.

The Drake service department TR-7 check out procedure explains how to
determine if the R/T pin diodes are working correctly among other
things. You can find that documentation at
http://www.zerobeat.net/drakelist/tr7bookalign.html

The calibrator diodes usually cause the radio to suffer on both transmit
and receive on the higher bands and UM9401 failures normally also cause
instability on transmit although they can fail and only cause problems
on the higher bands only.

Hopes this helps.

73's

John Loughmiller

DE KB9AT

.

kg7da wrote:

> I can only get about 100 watts out on 20 meters and less on higher=20
> bands.I get 150w on 80. even turning up alc control doesnt help.
>
> any ideas?
>
> tnx
> Marty

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-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Steve Garwood
Sent: Saturday, April 06, 2002 10:36 PM
To: Drake List
Subject: [Drake] TR-7 problem

I have a TR7 that is experiencing low transmit....  I only have around
10 watts of RF output on 10 meters,  Power increases on the lower bands.
On 75 meters, power output is around 100 watts.  There is also no ALC
light on the high bands.

This sounds like the problems that I had heard about concerning the PIN
diodes.

Are new PIN diodes still available?

I'll be digging into the radio shortly after I review the service
manual....

Thanks for any help on this one.....

Steve

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D
Steve Garwood, N=D8CZV / USAF MARS  AFA1GQ
Attica, Ohio
[email protected]

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=3D=3D

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