[TVARC] Ameritron amplifier tubes

[John Ellis]

Richard,

Lots of folks use the 811 or 811H, so I am
responding to the group. The 811 tube has
4 pins on the base, just like the 572. The two
large ones are for the filament, one of the small
ones is for the control grid. I have seen where
some 572s use the *other* pin for the grid and
some use both pins paralleled. So, if you swap
the 811s for 572s, just be aware of that anomaly.
Running a jumper between the 2 pins of all 4
tubes should work.

If 572s are not available, 811s or 811As  should
work fine, that's what the amp was designed for.
RF Parts Co. is another source. If you strike out
on both of those, any of the larger ham radio dealers
should have a source. Remember, there is just not
too much demand for vacuum tubes these days
so there is not much incentive for people to make
them. I had good luck with the Russian ones.

73,
John, NP2B

On Wed, Oct 28, 2020 at 3:42 PM Richard Antolick <ra77 at rantolick.net> wrote:

> A friend from high school that used to sit with me in dad’s basement while
> making contacts 45 years ago got his general earlier this year and has
> setup a station.  He bought a used Ameritron 811H amplifier and is
> concerned the tubes are on their last legs.  He got some advice on
> replacing with 572B tubes.  I have no experience with these amps but from
> some web searches the 572B is said to be more robust but might require some
> mods to the amplifier.  Any advice for my friend Ron KC3PUV on the tube
> change and if mods are required, also a source for the 572Bs.  DX
> Engineering is out of stock indefinitely and he is leery of the Russian
> version.  Thanks.
>
>
>
> Rich
>
> W4RJA
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-- 

John Ellis         (NP2B)
1149 Mockingbird Lane
The Villages, FL 32163

telephone 352 633-2910
facsimile  352 633-0401
mobile     340 513-4928
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