heathkit AT-1 keying

[Tom NØJMY]

Hi Joe.  As a rule, keying an oscillator and minimizing chirp are two 
mutually exclusive concepts.

You could key the cathodes of the 6AG7 and 6L6 together.  To minimize 
the chirp you add a few discrete components: a zener and a couple 
caps/resistors to sequentially key the rig.  The oscillator comes on a 
split-second before the final and stays on a split second after the 
final cuts off.  I have the circuit from 73 or HR around here somewhere.

This can also be accomplished with a couple of miniature relays in a 
small project-box, all from Radio Shack.  Better yet, this circuit can 
be used for QSK T/R switching up to about 20 wpm (YMMV) which kills two 
birds with one stone.

Another solution is to leave the oscillator running but shift it's 
frequency 2 or 3 kHz. out of the receiver's passband on "key-up".  Very 
simple.  This uses a diode and a cap, as I recall.

Both of these last two circuits were in a Hints and Kinks compendium 
some time back.  Also on the QST CD's.  I've got them around here 
somewhere, too.  I could go an an archaeological expedition and dig them 
up for you if you like.

I'd be interested in what the other fellows have to say.

Good luck in your search,
Tom

www.hayseedhamfest.com

joe wrote:
 > HELLO
 >
 > DOES ANYHONE OUT IN RADIOLAND HAVE A CIRCUT  TO ENABLE KEYING
 > OF THE 6AG7 OSCILLATOR STAAGE ON THE AT-1. ??  WITH A MINIUM
 > OF CHIRP AND CUTTING OFF THE 6AG7 OSC STAGE  SO THE OSC DOESNT RUN
 > ALL THE TILME.
 >
 > JOE W0TUT

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