[Elecraft] How to center K1's crystal filters?

[Don Wilhelm]

Ken,

You are correct, those K1's without the S2 switch make matters more 
difficult for setting the Transmit Offset.
There is a procedure in the older K1 manual which has you short two 
solder pads on the RF board to make that adjustment, but it does not 
work as well as with the K1's with the switch.

My procedure for adjusting the TX offset on those older K1's is more 
complex.
After adjusting the BFO to position the center of the FL3 passband at 
the desired sidetone pitch,  I set the K1 to receive a signal at the 
same desired pitch.  A signal generator is a handy tool, but an off the 
air signal can be used if a signal generator (such as another 
transmitter operating into a dummy load) is not available. If using an 
off-the-air signal, make sure it does not change frequency - ARRL 
bulletins or code practice signals are a stable source of on-the-air 
signals.
Receive that signal generator (or on-the-air signal output) on the K1 
and also on a separate receiver, and then do a TUNE with the K1 (into a 
dummy load).  Adjust the K1 C13 to the same audio pitch that the signal 
generator (or on-the-air signal) frequency produced in the monitor 
receiver (Spectrogram or other audio spectrum analyzer is helpful in 
determining that pitch - any frequency will do - the important thing is 
that the audio frequencies are the same).

You can try the procedure in the older manual, and if successful it will 
produce the same result, but my test bench is set up with Spectrogram 
and a monitor receiver, so the above procedure is the easiest for me.

73,
Don W3FPR

On 1/25/2016 9:16 PM, Ken Talbott wrote:
> You said you built your K1 'years ago'.  Are you sure you have an S2?  If
> yours is an early K1 there is no S2, this process is a bit more involved!
> Don, can you help with those instructions?  They are not in the current rev
> of the manual.
> Ken - ke4rg
>
>