Monday, January 30, 2012

Unode Biased Push-Pull FET

This is my new Homebrew "Vacuum Unode Biased Push-Pull FET Power Amp" of my own design.

Unode? - with the vacuum tube containing only one element, look closely, you will see, I did not know what else to call them :-)  And, I like the name and the glow.

I have experimented with this type of bias for FET Power Amplifiers before. Building some Amps with varying degree of success. The Unodes (lamps) are used as a Positive Temperature Coefficient (PTC) element providing a nice stable bias environment for power FET's.

Unode Biased FET Power Amp

This is the prototype, with Homebrew PCB being planned (and soon created). Performance measurements, Low Pass Filter, and other part modifications will most likely follow. For now the Amp is doing a smoke test. Power and Spectrum measurements will soon follow.

A real Toner Transfer PCB will eliminate the Grounding Solder Globs and make the amp much more presentable. Soldering over the edge of a Manhattan pad is always difficult. Next time I build this style of prototype board, I will use Solder Wick for the over-the-edge ground connections.

This power amp (in it's final form) will be used with my Propeller WSPR, QRSS, and OPERA Beacon.


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