[Amps] Motorola 375w VHF amp w/ 2x8560AS

Eric Dobrowansky kk2ed at comcast.net
Thu Sep 18 02:20:06 EDT 2003

Hello ALL,

I am attempting to bring a 153MHZ Micor 375w 2x8560 PA down to the 147MHZ
ham band.

Currently, the grid and loading controls tune/peak with no trouble, but the
Plate cap is at it's maximum before I quite reach resonance. The amp
efficiency isn't all that good either - 260ma Plate @ 1400v keydown yields
about 125w output, about 35%.

Has anyone modified one of these "Motorola Micor" rf decks?  Can I just add
some capacitance (ie: a doorknob cap or two) in parallel with the Plate
tuning cap? How much -5-10pf?

Has anyone made notes or documented the re-tuning of one of these amps to
the 2m band?

Any suggestions greatly appreciated.


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