[Amps] APT ARF-1505 FET's for HF amps

[Dan Levin]

> It looks like Advanced Power Technology has some 300 volt
> VDMOS FETs that do 750 watts in modes A-E (ARF1505).
> A push-pull pair of them would be very close to legal
> limit (US) from one module.  

We looked at these FET's for Project Gamma.  Cooling a 750 watt point source is a huge problem.  We decided after discussion with APT's applications engineer (who is a ham) that we would be better off with a larger number of smaller parts.  I believe that Elecraft reached the same conclusion.

APT is suggesting the use of their ARF-463A/B pair of parts running at 60 volts.  Each four FET module would deliver around 400 watts, four modules delivers full power.  Much easier to cool than the 1505, and running these parts at 60 volts should make them pretty much bullet-proof (these parts have a breakdown voltage of 500 volts).

ARF-463's are ~$70 per pair in quantity one from RELL, so the amplifier would need $560 worth of FET's.  Compare that to $88 per matched pair of MRF150's in small quantity - or a total cost of $704 for 16. 

Our only concern with the APT parts for Project Gamma was the need to design and build a 60 volt power supply, whereas using MRF150's allows the use of surplus telecom 48 volt power supplies which are available very cheaply.

                          ***dan, K6IF
                          http://www.k6if.com/ssamp