Steve Katz wrote:
> Along the same line, different amp:
>
> Tom, have you tested any of the Mirage VHF amps?
>
> I have a few which don't seem to do well. Never tried to specifically
> measure IMD, but they're not anything close to linear once operated at maybe
> 50% of rated output power. 1 dB compression occurs at maybe just over 50%
> rated output, and at 100% rated output they're in heavy compression (CW
> signal, 14Vdc power). Not just one, but a few different models....
The transistors used in these sorts of amps are usually designed for VHF
mobile radio use - class C, heavily into saturation for high efficiency
at the rated power, inherent current limiting for high VSWR tolerance.
These are things that kill linear operation, the 50% output you see at
1dB compression is about the best they can do. Moving to 28 or 50V makes
a world of difference.
Steve
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