[AMPS] PA Recommendation Wanted

[Ian White, G3SEK]

KM1H wrote:

>Ya gotta remember that the average amp "OWNER"  does not have a clue to
>what he is doing....much less how to match his radio to his amp.
>

"Match" in the sense of "adjust to be compatible" - oops, sorry, wrong
newsgroup!


>On VHF/UHF it is even worse with clowns running 4CX250's at 2500V and
>nary a thought about bias or screen voltage stability, impedence, etc. At
>least on HF the band noise covers most of that crud....on VHF we are not
>so lucky.

Carl is right on two points. It's the operators and the power supplies
that are to blame, not the tubes themselves.

The second point is that at VHF/UHF, the background noise levels are so
low, and the ERPs so high, that dirty transmissions are very noticeable.
Suppression of splatter (intermittent high-order IMD) and noise
sidebands becomes very important. The RSGB VHF Contesting Code calls for
at least 90dB ultimate attenuation of in-band unwanted products; more if
you're a big signal.


73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)

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