[Hallicrafters] Hallicrafters HT-33A
Roger (K8RI)
hallicraftersgroup at rogerhalstead.com
Fri Sep 19 00:09:36 EDT 2008
Carl wrote:
> There are several choices from the USA, China, and Svetlana depending
> on work involved and acceptable expense.
>
> 4CX1000A, 4CX1500A & B, 4CX1600B, 5CX1500A & B.
>
> There are also numerous Russian triodes as well as the USA 3CX1000A7
> and the 8877.
>
If you hunt there are PL-172s and 8295A out there, BUT it may take some
work to find a good one. Most, or many of the PL172s are gassy. If the
guys would stick them in the amps and let them cook every few months
there'd be more good ones. 8295A tubes are the most desirable and
although the PL-172 has a "/8295A" on it a true 8295A is a ceramic and
metal Pentode while the PL172 is glass and metal. The 8295A is about a
1/2" taller than the PL172 but there's plenty of room in the HT-33A and
B. If you can find either tube guaranteed it's worth a small fortune and
considerably more than the amps sell for with the 8295As going for about
twice the price of a PL172. Most pull out 8295As aren't very expensive,
nor are the PL172s. The problem with those 172s is as I stated before,
so many of them are gassy. I've picked up two HT-33Bs over the years
for about $300 to $350.
I don't know of any that are direct "plug-in replacements. The 8877
although rated at 50% more power is considerably smaller than the
PL172/8295A and takes a much better cooling arrangement than what the
HT33 A and B has. That was one of the nice things about the original
tubes. They only needed a fan blowing air up around the tube and
socket. That fan didn't even have a shroud.
I don't know about the other tubes but converting to an 8877 takes some
physical mods with a bit of care to make it look good. I think the
others are also smaller in diameter.
I don't know about the "A" model, but the "B" easily puts out the legal
limit with my voice characteristics even with that 110 volt primary. It
does take a good hefty (short) run of #10 for the AC power if you don't
want to see excessive voltage drop.
73
Roger (K8RI)
> Carl
> KM1H
>
>
> ----- Original Message ----- From: "Glen Zook" <gzook at yahoo.com>
> To: <hallicrafters at mailman.qth.net>
> Sent: Thursday, September 18, 2008 8:31 PM
> Subject: [Hallicrafters] Hallicrafters HT-33A
>
>
>> I just obtained a Hallicrafters HT-33A linear with a bad final
>> (PL-172). I believe that there have been some articles on changing
>> out the tube with a more readily available tube. However, I have
>> been looking on the Internet and just cannot find any. In this case
>> google is not my friend!
>>
>> Does anyone have a suggestion as to where I might locate this
>> information?
>>
>> Glen, K9STH
>>
>> Website: http://k9sth.com
>>
>>
>>
>> ______________________________________________________________
>>
>
> ______________________________________________________________
>
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