On 4/13/2011 8:31 PM, Gudguyham@aol.com wrote:
>
> In a message dated 4/13/2011 8:22:42 P.M. Eastern Daylight Time,
> km1h@jeremy.mv.com writes:
>
> If you can find PL-175A's they will equal a 3-500Z watt for watt..
>
>
> Carl, I know you have a few years on me, so when I came on the scene the
> 3-500's were so popular that the PL-175A tubes were history by then. Sure, I
> have tried 4-400's in place of 3-500's so I know that they work OK in GG
> with a little less gain. I have never tried a PL-175. As I recall didn't
> Hallicrafters make an amp with that tube? I looked up the 175 and it seems
> it is a tetrode. When you mentioned it before, did you mean "watt for
> watt" in GG or AB1?
>
Hallicrafters sold the HT33A and HT33B which are different iterations of
the same amp. They used the PL172/8295A which was a glass/metal external
anode pentode with a 1 KW anode dissipation. The anode is quite large
with a coarse fin structure making them easy to cool without a lot of
back pressure. The PL172 with the glass to metal seals tend towards
getting gassy and particularly so if they just set around. There is
also a straight 8295A which is the ceramic/metal version of the same
tube. IIRC they are almost double the size of the 8877 and tested used
ones may bring more than a new 8877. They are easily worth more than the
price of the HT33B. They were brining $2400 USD for a tested and
guaranteed used one a couple years back.
Tested good used ones (without the guarantee) are considerably cheaper,
but OTOH still expensive.
73
Roger (K8RI)
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