Need directions on Bias setting? AMPLIFIER

[Bombardier]

 

[brandon7861]

The quiescent drain current is listed on the dxworld website as 500mA each mosfet.

HF LINEAR AMPLIFIER BOARD 600W 1.8-30MHz | Dxworld-e

HF LINEAR AMPLIFIER BOARD 600WMOSFETS NOT INCLUDED YOU CAN USE MOSFETS SD2933 VRF2933 OR SD2943FOR SD2933:RF INPUT: 10W MAX SSB/CWRF OUTPUT: 600W MAX SSB/CWFOR VRF2933:RF INPUT: 10W MAX SSB/CWRF OUTPUT: 700W MAX SSB/CWFOR SD2943:RF INPUT: 10W MAX SSB/CWRF OUTPUT: 700W MAX SSB/CWFREQ:1.5-30MHz...

www.dxworld-e.com

The MicroSemi datasheet over on Mouser has a 300w single mosfet test circuit that shows 250mA bias.

 

[brandon7861]

I have no manual for that, but I'll take a guess at the procedure. I assume the bias button provides power to the bias network in the absence of an RF signal. Being I see no convenient jumper to remove for measuring the mosfet drain currents individually, I would have to guess the procedure would be something like this: While watching the current meter, adjust both potentiometers so the current draw is the lowest (being careful not to let it go high by turning the pot the wrong way). At this point assume both mosfets are off. Then, from that current reading, with the button pressed, turn one pot until the current into the amp increases by 500mA from what it was before. Then, turn the other pot for another 500mA increase and release button.

 

[Bombardier]

Thanks for the late reply,all works great Thank you very much.Mark....

 

[Rwb]

View attachment 57933

wow the soldering sure wouldnt pass quality control at eagle pitcher and the jagged bare ground wire looks spooky from my observations