Heath 301/401 CW problems in tranceive mode

[Darwin D. Geiselbrecht]

In an offline response to an earlier post, someone asked what kind of problems
I had experienced when using the 301/401 in CW tranceive mode (saying also
that he had not experienced problems with 303/401).  I am posting the reply in
hope that others may have worked out some of the issues (or I may find that
mine are unique).

.....
 My experience with the SB-301/SB-401 combo in tranceive mode relates to the
following:

1. The SB-301 does not contain a regulator on the B+.  As such when using the
RX  HFO in conjunction with a setup that contains a high power amp (SB-221)
and the poor regulation of my rural power line, the HF crystal oscilator tends
to a slight chirp on the higher bands in spite of it being crystal controlled.
Also, the lack of B+ regulation leads to a slight frequency shift with
changing line voltage when my 5 ton Texas air conditioner kicks in. I added a
regulator tube on a bracket below the chassis in one of my SB-301's and it
seemed to cure this one.  You would not see this problem with the SB-303.

2.  On both the 301's I have, the drive level of the HF osc is marginal on the
higher bands. The circuits must be carefully peaked with the cables in place
(the correct ones) .  I believe that the fundamental problem here is that  the
HF osc amp stage should have been designed into the SB-301 rather than in the
401 as it is.  Of course, that would have been extra circuitry when the 301
was used stand alone. Like I said, it works, but I have never been happy with
it. Again, you probably wouldn't have seen this on the SB-303, I believe that
it contains a HF osc buffer in the RX.

3. I'm stretching the old memory on this one, so I may stand to be corrected,
but the BFO offset feature you describe is at the heart of one of the problems
with the combo.  As I remember, in CW mode the 401 always uses its internal CW
BFO.  This is why the basic TX (without option pack) includes the CW crystal.
This osc is offset by 1KC from the 301 CW BFO and runs all the time in CW
mode.  With the cables in place. the 1KC beat is usually audible in the 301.
Note that this issue does not occur on SSB where the RX BFO is used  I dressed
up some cables and used RG-174 on some runs in the 401 and it helped some, but
the right answer would probably be to take the B+ off the TX BFO at the right
times. . I seem to remember that I could not find the right switch and relay
lugs to do it. It is possible that the wiring/buffering in the 303 does not
offer sufficient coupling from the 401 BFO cable such that the beat is
inaudible.

4. The 301/401 does not contain RIT, so "tranceive on CW" would usually mean
using the TX VFO, especially when chasing old boatanchors and Hartley's around
the band.   At that point,  you might as well use the units as separates.

I have never tried tranceive with the 303.  Since I operate exclusively CW
with the Heath's I much prefer using them as separate units. Since acquiring
the 303, I have never had the desire to hook up the cables.

73 Darwin K5DOA

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