[Hallicrafters] HT-37 Low Power Output

[David C. Hallam]

Paul,

I would first suspect the finals.  Try replacing them with new or known good
6146's or 6146A's.  Don't use 6146B's or 6146W's unless you plan on
resetting the neutralization.  These later types have different
interelectrode capacitance and MAY require neutralization if you use them.

Unless you have fiddled with the neutralizing capacitor, neutralization has
nothing do with your low output problem.

Also the 12BY7A driver runs very hot and you might to try substitution here.
12BY7A's are used as a driver on a lot of these old tube type transmitters.
They run hot on all of them.  I use one of the black IERC shields on all of
mine to reduce the temperature.  Any of the other types of tube shields
actually increase the tube temperature as they hold in the heat.

Check the bias on the finals as per the procedure in your manual.

David
KC2JD

> -----Original Message-----
> From: hallicrafters-bounces at mailman.qth.net
> [mailto:hallicrafters-bounces at mailman.qth.net]On Behalf Of Paul Adolph
> Sent: Wednesday, January 03, 2007 2:16 PM
> To: hallicrafters at mailman.qth.net
> Subject: [Hallicrafters] HT-37 Low Power Output
>
>
> Hi,
> I found this group and went through some of the archives. I have
> a couple of
> Hallicrafters receivers and 1 hallicarfters transmitter and found
> a lot of
> great information. I thought I would ask the group a question I have
> regarding my HT-37 transmitter.
>
> I have operated the HT-37 for 3 years now and it has provided
> full output.
> I get great audio reports with it using a D-104 mic and I really
> enjoy using
> it.
>
> I was using it this past week and noticed reduced output on the
> wattmeter I
> run it through. (the meter works fine with other transmitters). The
> wattmeter has a built in dummy load.  I have a frequency counter on the
> external antenna relay so I know exactly where I am tranmitting.  The
> transmitter meter seems to work as normal during tune-up on each band and
> the frequency counter reads the frequency but the wattmeter shows
> about 12
> watts out on CW,  5 watts out on AM and about the same on SSB when I talk
> into the mic.  That's on 80 meters.  The other bands the power is more
> reduced as I check through 40, 20, 15 then 10 meters.
>
> I have never experienced 6146's getting weak or going bad so I
> don't know if
> 1 or both tubes are bad or need neutralizing so I don't know what
> to expect
> from bad output tubes.  The problem could be somewhere else but
> I'm not sure
> where to look.
>
> Other than the power output problem the transmitter seems to operate fine
> and if not for the wattmeter I would not know anything was wrong.  Do you
> have any suggestions on what could be going on with this transmitter?
>
> Thanks for your help with this,
>
> Paul Adolph (N3FTL)
>
>
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