[AMPS] RCA 7213

[Ian White, G3SEK]

Larry Molitor wrote:
>Does anyone have any experience with a RCA 7213?
>I have one and thought it might be interesting
>to run it triode connected grounded-grid. Any 
>pertinent thoughts would be appreciated.

It would be a terrible waste. Using a UHF tube like a 7213 on HF would
be like using a high-spirited racehorse to pull a cart. Worse than that,
in triode-connected grounded grid (TCGG) the poor beast would be dead in
six months.

I don't have the characteristic curves for a 7213, but most of the RF
drive in TCGG goes into the control grid, and modern ceramic-metal
tetrodes do not have the control-grid dissipation to handle that - and
in TCGG you can't even measure the screen and control grid currents
independently. If experience with 4CXC250s is anything to go by, TCGG is
a quick, sure way to ruin the tube.

The 7213 is rare and desirable for use at UHF, so why not trade it for
an 8877?

73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           http://www.ifwtech.demon.co.uk/g3sek

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