Paul Sokoloff, WA3GFZ, wrote: > I am looking for an Ameritron AL-811 or > any good amplifier of medium power (200-300 > watts AM) that would also do 160 meters. > Any opinions on the Ameritron. I am not > familiar with the unit, but it looks like > it will fit the bill
No, it won't, but through no fault of the amplifier. You need a *lot* more plate dissipation to run 200 - 300 watts out. Here's my thinking: First, carrier-level efficiency for a linear amplifier running AM is 33%, best case. This means that at 250 watts out, you will be burning 500 watts off the plates of the tubes. Think 3-500Z. But you really shouldn't run a '500 at max plate dissipation full-time. Think two 3-500Z's. Now for the power supply. It has to crank out 750 watts average power, with peaks of about 1500 watts - 3 kV @ 500 mA. Quite doable with just about anything out there and no real problem. The Ameritron amplifier you should be looking at is the AL-82. Or anything that runs a pair of 3-500's. I run about the power you are looking for with my old Heath SB-220. After a typical old-buzzard AM transmission, the 500's have quite a bit of color on the plates and the shack temperature has gone up 10 degrees. Bottom line: You need a lot of plate dissipation to run low-level-modulation AM. Jim, K7JEB Glendale, AZ
