SB401/301 combo on CW

Stewart Lyon stu_w6cux at JUNO.COM
Tue Nov 3 20:20:58 EST 1998


Hi Gang,
I have been using my SB401/301 on sideband and find them a very
satisfactory setup. However, I intend to try my hand on CW during the
Sweepstakes this year.  I find that the SB401 is a great CW transmitter
and the SB301 a great CW receiver but together they are not so great. I
know a lot of you folks use this setup on CW so there must be a better
way than in the Heathkit manuals.

First, the sidetone setup. The way it is now the speaker line is routed
through the transmitter where it is switched to a sidetone generator on
transmit. What happens if you want to use headphones? Joe Lutz found a SB
on this but he couldn't read it. How do you CW folks do it?

I prefer to monitor my on-the-air signal rather than use a side tone and
have modified by SB301 to add a "key down gain" scheme.  The problem is
that the SB401 outputs a signal from the carrier generator board when on
the air in the TRCV mode and all the time in the TRAN mode. Has anyone
tried to key the carrier generator crystal along with the mixer and 6CL6
driver? Wonder if it would chirp or be mushy?

The third complaint I have that maybe someone has solved is the pulling
of the -301 LMO whenever the -401 is switched to it (as in the LOCKED
mode)  The frequency changes about 2 KHz. This because of the additional
load of the tx mixer. It seems to me the -301 should have another buffer
for the LMO like there is for the BFO. Maybe I'll add one if I can
remember how to design tube circuits.

Anyway -- any and all comments welcome. (Except about not modifing -- too
late for that.)

73, Stu - W6CUX
Winnetka, CA
ARRL Life Member

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