KM1H wrote:
>New or good used are getting scarce here also. Too many hams are burning
>them out with excessive HV, water jackets, etc.
Most of the failures are due to incorrect loading and no grid current
meter! The output coupling on many 1296/2304 cavity amps doesn't really
work, and hardly ever has a real loading control. And if you look at
published power supply schematics for these amps (eg the N6CA design)
there is never a grid-current meter.
It would be insane to operate a triode HF amp under those conditions,
but apparently it's OK with 3CX100s...
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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