Bias level for REV24 P.A. board

[marc]

Hi DR hams

I would like to know if any member of the community has an idea of the bias current of the two driver transistors and the RD100HHF1 on an Apache REV 24 board?

By default, I would say 250mA per RD15HVF1 and 1 amp per RD100... but it's a doubtful guess


VY 73'
Marc f6itu

[n1gp]

Hi Marc,

Here's a doc I tucked away from W1AEX detailing the bias procedure:

https://www.dropbox.com/scl/fi/gwmy50p8 ... 0e9yv&dl=0

-Rick / N1GP

[DH1KLM]

Hi Marc,

According to Doug / W5WC the following values ​​should be set:
Driver: 250mA each.
Final: 1000 mA each.

[w-u-2-o]

Be aware that, because the thermal design of the ANAN units is marginal, and because the bias supply is not temperature compensated, when you go through the procedure as described you can wind up on a wild goose chase. Once the unit is keyed down and adjustments commence, the devices will rapidly heat up. As they heat up they consume a different amount of current, even at low power output levels. You need to proceed through the adjustments very rapidly otherwise they will wind up changing quite a bit from first to last. And because of this the adjustments will never be exact, and will still vary with temperature during normal use.

P.S. Marc--this is why you always post publicly instead of sending a PM. You get much better answers!

[marc]

Hi all

Many thanks to Sigi, Rick & Scott

@ Scott : Since I'm an obedient boy, I followed the recommendation in the "user's guide" section ;- )). So I started with a direct message.

Your warning is indeed important. I learned it the hard way a few decades ago, when I built my first linear amp. (A first generation G6ALU... memories!).

Thanks for the document Rick. I digg in the W1AEX site without finding this info. The RD100 bias makes sense to me, but the RD15 bias may be a bit optimistic. The setting on the analyzer and scope will be the final judge.

And once again, a big Thanks to all

VY 73'
Marc f6itu

[w-u-2-o]

Hi all

@ Scott : Since I'm an obedient boy, I followed the recommendation in the "user's guide" section ;- )).

Just out of curiosity, and since there are so many "user's guides" floating around, what exactly was the recommendation?