I built this project and it works very well. I used a heat sink
substantially larger than the one the author used. I have had no thermal
problems. I built it with a switchable attenuator so that I can feed it
with 5 watts or 1 watt for full output. I get 50+ watts out on 40
meters, nearly 70 watts on 30 meters, and 60+ watts out on 15 meters. If
you do manage to blow the finals (which I have not), they only cost 75
cents each. The 28 volt power supply was a pain.
Nice design, and it works.
Regards,
Mike Maiorana, KU4QO
Bill Wiese wrote:
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There's an nifty little 1.8-30MHz power amp recipe in there; it's
based upon two power MOSFETs that seem more intended for switching
power supply use than RF use - nevertheless these little buggers work
fine thru 30MHz (there's a tad of drop-off on 10M but it's still a
useful unit) without spectral problems, distortion, etc. [The output
of this amp has switch-selected lowpass filters for the HF bands to
cutout harmonics/TVI.]
