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Curt, Thanks for the quick reply.? To test the Two-Tone generator, I fed its output through an attenuator to my uBITX and tuned to the expected distortion product frequency.? I couldn't hear

David I cannot easily see from here - but possibly you are only looking at the amplifier ITOI by itself, and not its impact on the chain? Farhan had placed a cumulative calculation tool at his

Greetings from North Carolina.? I'm a uBITX owner and have lurked on this group for some time.? Lots of good discussion. I have built a fairly close copy of Farhan's Specan analyzer, plus the

Evan, both bias pots are set fully CW, zero gate voltage. In SSB mode, the TX idling current is over 900ma. Something is pulling a lot of current but nothing seems hot. In RX the current draw is about

Barry, The best way is to measure the current is to first rotate both bias pots to full clockwise position, ?note the current, then increase each pot one at a time to get the total current 200 ms

Can someone give me an idea what typically is the V6 current draw in SSB mode with no modulation? Thanks Barry K3bo

Well, I haven't done it yet to the uBitX, but here is Evan's picture of how he did it: /g/BITX20/message/83186 and that is what I plan to do when I remove the boards to make the

Thanks, John. Do you have any recommendation for leaded parts? - Jerry KF6VB

Jerry, for surface mount parts I mostly use the ATC100B 500V series. For larger capacitance values parallel lower values to keep your voltage rating high as they de-rate with capacitance ....but

*** Do you have an exact series to recommend? Starting from scratch with a Digikey search is daunting. This particular LPF probably likes leaded parts - the lands are too far apart for SMD. I

Jerry, 3kv caps for 70W? I use 500V caps for 600w and they just loaf along.Filter caps need to be able to take lots of circulating current. If you use those small caps from Hilitchi you should use

Vic, where did you install the back to back? -- Frank, KG9H

Yeah, it doesn't make much sense. I was thinking about RF in the shack - RF sometimes does strange things. I put the amp on the bench just to look at it and measure the quiescent, which is 228 mA.

That seems hard to achieve. Maybe you are over driving the amp and possibly also the tinysa. If you have an attenuator available, see if the harmonic drops more than the attenuation. Curt

Vic Interesting misfortune. A 500w amp remains on my wish list. Switching diodes and maybe even transistors are often even more vulnerable when not biased. I am thinking try using the leaded parts

Thanks for reminding me, Arv. I used to know this stuff pretty well, but that was over 40 years ago. Time to review. In the meantime, I took the uBITX and the amp off the desk, lest I be tempted to

Frequently there are comments regarding the proper bias setting for transistor amplifiers (BJT and MOSFET). For SSB, in order to minimize spurious emissions you want to operate your finals in the

Characterizing the Chinese amp/LPF with the TinySA... Second harmonic not too bad. THIRD harmonic OTOH is consistently 10 dB higher than the fundamental! Think I need to look at the biasing on that

So my adventure with the CCLPF ( cheap Chinese...) continues. I started by characterizing the existing filters with a NanoVNA. Enjoying the learning curve on that one... The 80M was just weird -