2 Meter LDMOS Amp Project

Post Script - After the trip I got the idea in my head that having a LDMOS amp for 2 meters that can do up to a full KW would be a fun project. I figured having several more db when out and about putting grids on wouldn't hurt, and adding another Yagi will make me EME capable for a trip to Wyoming next summer.

Here are the photos of the amp project. I'm using a -10db pad on the input so 7 watts drive from the Elecraft K3/internal transverter gives me 550 watts. That's a very comfortable level for for testing.

I did finally swap in a -8db pad for 850 watts out - that was the design power level goal, and about what my generator can source when in the field. The amp draws 25 amps @ 48 vdc. I added a small fan inside to move some air over the output coax and LP filter when doing modes like JT65b.

I set my 9 element Yagi up in the driveway for a few days and made nine EME contacts, so the project seems to have worked out well. :-)

See Jim, W6PQL excellent web site for more info and top quality modules and parts.

The smoke test. 7 watts drive = 550 watts thru a -10 dB pad.

It all fits in a 8x12 chassis. My sequencer controls FET switches for the 48 vdc and 12 vdc supplies.

That is one mighty big heatsink, a 4 inch muffin fan will sit on top too.