by AB2EZ » Sun Jun 26, 2005 7:11 am
Bill
Super! I've been thinking about my next class E rig (even though I tell people on the air that one is enough for me) and I may want to copy your design. Can you post the schematic?
In my case, I'm using my class E rig in conjunction with my FT817ND QRP transceiver... which I've adjusted (using the software-controlled features) to put out 1 watt of (unmodulated) carrier on AM. The output of the FT817ND is very stable, and it seems to be able to put out 1 watt indefinitely...without any heating problems. That matches perfectly with the 1 watt input requirement of my driver design.
Prior to switching to this new driver design, I was experiencing a lot of problems with instabilities that would lead to the loss of an FET. I discovered, recently, that the driver I was using previously had a tendency to produce strong 2nd, 3rd, or fourth harmonics... depending upon how it was loaded. Since I have switched to this modified design (basically adding one inductor) my rig has been very stable... and I am now a very happy class E camper.
I agree that using a design that works with about 1-2 volts peak into a 50 ohm swamping resistor (input load)... i.e. a driver that requires ~ 10-40 milliwatts of r.f. input ... is an attractive alternative for many situations.
Best regards
Stu
Stu
Bernardsville NJ