Robert -
Robert Sisco wrote:
Dear Drakies,
1) I had the bright idea to replace the tubes in my R4B.
Now I can not zero or calibrate the S-meter. I was unable to find two
6HS6 tubes. I suspect this has thrown the S-meter bridge out of
balance. It worked fine with the weak tubes. Where can I buy a set of
6HS6 tubes?
Replacing ALL tubes in a unit is NEVER a good idea. First of all, not
all "NOS" tubes are good! Also, MOST "current" tubes are GOOD. 6HS6
tubes are expensive, ~ $20 each. The good news is your old ones are
probably fine. The S-Meter ZERO and CALIBRATE is affected by V2, V3, V4
and V5. A "gassy" tube in ANY of these sockets can cause problems, not
to mention a bad tube. V4 and V5 are the most likely suspects, since
they are the most prone to this sort of problem. V3 is a secondary
suspect, and V2 is the least suspect. I would suggest putting ALL your
old tubes back in the receiver and see if it still works! Then if it
won't meet specifications, i.e., clearly hear a noise peak when
adjusting the Preselector on all bands with no antenna, try substituting
ONE tube at a time. If nothing changes, put the OLD one back in and go
to the next. Simplest to start with V1 and work your way down to V5.
You can swap V2 and V8, as V8 is much less critical.
2) I have a TR4CW. I was tricked into buying it, when I thought the CW
stood for morse code. I do not operate SSB. Has someone already
figured out how to change the IF crystal filter for a narrow bandwidth
for CW?
"CW" does stand for Morse code, at least to Hams. There SHOULD be a 500
Hz narrow filter already there, it came with one from the factory. That
filter is selected by the red "500 Hz" on the SIDEBAND switch is for.
What center frequency do I need to use? I can always restore the TR4CW
to original, should the need arise. In the mean time I will be using
an external receiver with selectable bandwidths.
3) I see there is a RIT modification for the TR4CW. Does someone have
a reprint of that article?
There is no "effective" RIT "modification" for the TR-4Cw. The
TR-4Cw/RIT used an entirely different PTO to incorporate RIT.
All that said, you'd be MUCH happier with a T-4XB to go with your R-4B
if you primarily (or ONLY) operate CW. MUCH better station for CW
operation. The TR-3/4 was designed as an SSB transceiver for mobile
operation. The "Cw" was an attempt to at least work a little better on
CW than the plain TR-4/C by adding aa 500 Hz filter. Users soon found
that an RIT was a MUST for "real" CW operation, leading to the
TR-4Cw/RIT, which is still only a "fair" CW station.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
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