Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Tom -
As usual, "it depends".
First question is what is the serial number of your R-4A?
Second is, does it have a letter following the serial number?
3 - What is the letter at the end of the R-4B serial number?
4 - What is the letter at the end of the T-4XB serial number?
The letters are a color code for the Carrier Oscillator and BFO crystals
in the Tx and Rx. Ideally, the letters (and color stripes on the
crystals themselves, CHECK!) are the same in Tx and Rx.
All that said, this is ONLY important if you intend to operate SSB in
transceive mode. The "late" A and all B Line units had color coded
crystals to keep the "transceive alignment" stable over temperature.
Unlike the C Line, where the two oscillators are patched together in a
sort of phase lock, the A and B Line relied on the relative stability of
the two oscillators. Varying room temperatures, off to on and even in
some cases before and after a transmission all were enough to put you
"off frequency". Not enough to be noticeable on CW, i.e., < 50 -100
Hz, but plenty to get complaints from SSB contacts. And this was in the
days before "channelized" SSB brought on by the insufferable "digital
dials" with 10 Hz resolution!! :-)
Having the "wrong" color code combination can be even worse, since the
various colors represented different "slopes", some actually the reverse
of others.
Aside from this, some people claim that the "early" R-4A (13 tube
version, s/n below 4054) "sounds better" because of the tube type
Product Detector. The "late" R-4A (11 tube version) had the PD and
other "non-signal path" stages converted to solid state, and began the
color coded crystal system.
The R-4B began almost identical to the "late" R-4A, with the significant
change from bipolar to FET PTO after the first 1000 receivers at s/n
8000. Aside from that, the differences were mainly cosmetic. Things
like the "PTO in use" light, black lettering "above the belt" on the
front panel, slanted dial skirt, etc., essentially the little
refinements of a design after building 7000 units.!
Bottom line, either receiver will work just fine with the T-4XB, and if
you don't intend to operate SSB in transceive the differences are almost
all cosmetic. Which one is "prettier", has the least copper "crud", has
the least aftermarket "improvements", etc......
More than you ever wanted to know!!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Tom Bowman wrote:
Hi,
The subject line says it all. I have both an R-4A and an R-4B. I'm
going to keep one to transceive with my T-4XB.
What is the advantage of using the R-4B instead of the R-4A with the
T-4XB?
Thanks!
Tom, WA3REY
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