SB-101 frequency drift

[Glen Zook]

A little bit of drift, like 10 or 20 Hz isn't that
uncommon, but much more and you have something wrong.

The place that cuases a lot of drift in the Heath
SB-Line equipment is the circuit that shifts the LMO
frequency between USB and LSB.  If the voltage is not
extremely stable the frequency will shift around.  The
purpose of this voltage is to shift the LMO frequency
along with the crystal BFO frequency so that the
calibration mark stays the same between USB and LSB.

My Heath SB-110A (6 meter version of the SB-101) had a
bad habit of shifting frequency between transmit and
receiver (just about 200 Hz but that was enough).  I
finally had to put in a zener diode in the frequency
shift section to cure this.  The dial frequency was
shifted about 1 KHz due to the fact that I had to drop
the voltage a bit.  However, 1 KHz is well within the
range of the moveable calibration mark on the dial
movement so there was no problem.

Glen, K9STH


--- Pete <aa9nf at YAHOO.COM> wrote:

I do notice that the frequency drifts a little bit
back and forth during a QSO, both on receive and
transmit, even when the rig has been on and warmed up
for several hours.  Is this normal for this rig?







Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco


	
		
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