Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Darrell -
Nice job!
The 2-B came with Sylvania or RCA tubes when new. By the way, Zenith
didn't make tubes, and all Zenith branded tubes were made by Sylvania.
V2 can be problematic. The 6U8(A) is marginal on gain, and as it ages
the 18.0 MHz crystal will sometimes fail to oscillate. The oscillator
circuit is a little different in that it operates with fundamental
crystals below 18 MHz, and 3rd overtone crystals from 18 MHz and up,
with no switching. Anyway, the 18.0 MHz crystal is a 3rd overtone, and
seems to be "on the edge" in more ways than one. Changing tube to a
6EA8, with its higher gain, will make this circuit more reliable. Quite
a few 18.0 MHz crystals have been replaced over the years, when a simple
tube change would usually "fix" the old one.
The 8BN8 is correct also. The very first 2-A's had a 6BN8 here, but at
s/n 1000, it was changed to an 8BN8 for hum reduction. There is an
article at www.wb4hfn.com explaining the mechanism involved.
You're off to a good start!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
Darrell Bellerive wrote:
Darrell Bellerive <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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When I completed my first radio restoration project, an Heathkit GR-81, and
announced that my next project would be a Drake 2-B receiver, a few people
asked me to post my progress to the mailing list. I will cross post to both
the Drake ([email protected]) and Glowbugs
([EMAIL PROTECTED]) lists. I will also include "VA7TO 2-B:"
in the subject for those who would like to filter messages.
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