[TenTec] Corsair II >> Obnxious relay -----

[KF6ZZ@aol.com]

 Gentlemen :

  After two months as a CII owner, I finally decided to try my hand at CW 
operation; having heard such marvelous reports of the CII being the consumate 
world class CW rig ....

  So I plug in my trusty J-38 and start terrorizing the 40 meter novice band 
...

  And am greeted with this miserable raccous clacking and clucking after each 
line of code.

It sounded like a dying chicken inside the radio ...

Turns out that all the noise was coming from relay K1 on control board 80978.

K1 is used for activating a linear amplifier.

I am not running a linear.
I am running QRP 5 watts.
Relay K1 is not required for barefoot operation:
" ... this relay does not control any of the internal functions of the 
transceiver..." 
( a direct quote from page 2-3 of the Corsair II manual )

  So I start investigating, and find that it is easy to silence K1 for 
barefoot operation.

  All one has to do is disable the circuit
 that activates the coil of relay K1.

  From the 80978 Control board schematic ( page 3-32 of the CII manual ) it 
is obvious that transistor Q10 switches the K1 coil to ground to energize the 
relay.

Easiest way to disable this function is to short the base to emitter junction 
of Q10.
Now Q10 will never be activated.
And the drive circuitry into Q10 will never be able to tell the difference; 
and will not be compromised.

Q10 is located on the corner of the circuit board about a half-inch inch from 
K1.

I used a miniature alligator clip, and clipped it across the base-emitter 
leads of Q10. 

Reverse modification is a obviously a simple matter.

Now my Corsair II works like a dream. 
Velvet smooth QSK and PTT,
nice and quiet like the Scout.

I never did like noisy relays ...

-Phil   
KF6ZZ

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