[Hallicrafters] HT37 problems

[David C. Hallam]

Joe,

Check the 2nd mixer and driver tuning.  If you have full output on 80, you
should have full output on 20.  There is a tuning problem in these stages.
80 and 20 do not use the 1st mixer.

You can't null the carrier in DSB because you are transmitting some carrier.
This is AM output.

Check the bypass electrolytic is in the speech amplifier.  This may be the
cause of no audio.  I've had that problem.

The B&W network was designated 2Q4.  I don't know if they are a replacement
for Hallicrafters network.  Good luck on finding one.  I am looking for one
for a 6M SSB exciter I want to build from an old, old circuit published in
QST.

David C. Hallam
KC2JD

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net]On Behalf Of Joseph
Trombino Jr
Sent: Sunday, August 14, 2005 4:05 PM
To: Hallicrafters
Subject: [Hallicrafters] HT37 problems


OK...so now I have RF output on all bands although 10m, 15m, and 20m is very
low.....40m and 80m just about full output.

CW mode keys rig fine and output same as above.

Have a couple problems remaining:

balanced modulator section:  unable to null out the carrier in the DSB mode.

unable to get audio through the system in USB/LSB mode.

All tubes checked GOOD on B&K 747B tube tester...some replaced with used but
good tubes to no avail.

Any way to check the Z1 audio phase shift network???  Any replacements
available???  I recall years ago there was a B&W phase shift network out
there but can't remember the nomenclature.

Any and all suggestions/comments/speculations/thoughts are welcomed at this
point.

The Drake2B/2BQ I received last week are working FB.....now to get the
transmitter on the air for a nice vintage station.

                                            73, Joe W2KJ


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