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New 2 x 2 Balanced Class E rig with a new driver design

PostPosted: Thu Jun 23, 2005 5:31 pm
by AB2EZ
I have published pictures, on my Web site, of my new 2 FET x 2 FET balanced class E rig; along with a schematic and a detailed description of my new driver design. This driver requires ~ 1 watt of r.f. input, and does a good job of driving the balanced pair of output modules. It can drive a larger (e.g., 5 FET x 5 FET) rig with a stable, well-balanced signal on each of the gate buses.

http://mysite.verizon.net/sdp2/

Best regards
Stu
AB2EZ

PostPosted: Fri Jun 24, 2005 6:21 pm
by blaine
very nice
8)

PostPosted: Sat Jun 25, 2005 5:23 pm
by ke1gf
Stu, I designed (a year ago) a driver that drives 4 x 5 FET (FQA11N90) modules, with 3mW of input (swamped to 50Ohms) and drives each 5 FET module at 4Mhz @ 30Volts Peak-to-Peak. It's a machine!

Image

And haven't lost a FET since Christmas of 2003.

Regards,
-Bill 'GF

Looks great!

PostPosted: Sun Jun 26, 2005 7:11 am
by AB2EZ
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