[Hallicrafters] HT-33A amp followed me home

[Roger Halstead (K8RI)]

>From what I've seen recently and this is my own take:
They are a nice amp, but the 110VAC only means you need a good heavy duty 
circuit to the thing.

The amps work well, but the tubes are expensive...really expensive.  The 
problems with the tube is many tend to be gassy.  The PL172 uses a 
glass/metal construction where the Eimac 8295A is metal/ceramic and less 
likely to be gassy.  They occasionally show up at swaps at a reasonable 
prices, but you never know for sure what you are getting.

They are available with "I believe" a 30 day warranty from several tube 
suppliers.  Prices vary, but I was quoted $1200 for a PL-172 that would be 
good, to $2400 for a NOS Eimac 8295A

>    A Hallicrafters HT-33A hf amplifier with the Penta PL-172A final
> followed me home in the past few days. Does anyone have any mods that
> were pertinent to those amps that I should be made aware of? Also what
> is the approximate value of such an amplifier? It is in pretty good

The prices vary widely.  I saw a really nice (looked like new) HT-33B go for 
$1000 recently and I've seen some that looked almost as nice go for $300. 
The 33A is slightly less sought after.  Neither is rare.
I'm still looking for a straight HT-33.

As  side note, many of us who have working HT-33Bs would not part with them 
for $1000. Any one who has had to purchase a tube would probably say the 
same thing.  I'd love to have an Eimac 8295A in there, but no way am I 
paying $2400 for a tube for that amp. Although... If I won the lottery?

Prices have been trending down over the last year or so, but there are 
exceptions.

Operationally you can run them according to the manual.    Running those 
particular tubes at reduced ratings really isn't doing them much of a favor, 
or adding to the longjevity.  If they were all plugged in and run an hour or 
so every few months there would probably be a lot more out there that aren't 
gassy.  Just don't hit the grid too hard or it's all over for the tube.

Back "in the old days" when we were limited to 1 KW DC input (average with a 
1/4 second time constant on the meter), my voice characteristics gave a bit 
over 2 KW PEP out without pushing the amp.  With speech compression that 
dropped considerably, but they are capable of close to todays legal limit 
output.
With the price of the tubes, I'd tune and load according to the manual and 
they hit it a bit on the easy side.

> cosmetic condition except for a broken glass on the front of the
> multimeter. Any useful info on replacing that glass would be most

I had mine apart about 6 months ago, but I don't remember just how that is 
set up.  It's currently out of the cabinet so I'll take a look tonight.

Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)
www.rogerhalstead.com
Here's hoping the tube is a good one and it serves you well.
> helpfull.
>    Thanks and 73 from Fern
>
>
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