Toll_Free
Well-Known Member
The output impedance is SET by the class of operation, plate voltage and instantaneous plate current (read that as PEP plate current).
It has NOTHING to do with the tubes in the amplifier... EXCEPT for Cout and Cin, and for a smaller part, interelectrode C (to CB type amplifiers).
The 572s will run cooler, have MORE plate dissipation, have MORE grid dissipation, and are a better fit. They have SLIGHTLY more C on the output side, IIRC, BUT, they let the Pi circuit eat that up.
The ONLY problem you're going to have is if you try to get 3X572b power out.
I HAVE looked at Ameritron's website, and did find there are a couple differences between the two amplifiers.
I've swapped, LITERALLY dozens (like, 4 or 5 over the years) 572s with 811s, and have ONLY had one problem, and that was with a homebrew amplifier.
SOME people have problems with Yeasu FL2100s, but that's a Svetlana issue, since russians can't copy tubes about as bad as the Chinese. Yeah, they WORK, but a 4 cylinder diesel will PULL a tractor trailer.... I'd MUCH rather have a Cummins Turbo 6!
Good luck, most of what you read on the internet is opinion. And everyone has an opinion... Some have two, like armpits, they usually BOTH stink.
Enjoy that amp and those tubes. If you REALLY want to clean up the output section, get the parasitic suppressors from Ameritron for the 572s... BUT, those won't be exact, either, since they are designed for FOUR tubes, and higher voltages.
Better yet, get ahold of Rich Measures, tell him what you've done, and he can custom design a parasitic suppressor for your amplifier. Just DON'T say shyt about it being for <<10>> meters, or he won't help... Let him know you USE the amp on 10, though, because you have to design a suppressor to work on 10 meters different than one that will never see low VHF / upper HF.
Hope that helps. Glad you took the plunge. Keep us updated
--Toll_Free
It has NOTHING to do with the tubes in the amplifier... EXCEPT for Cout and Cin, and for a smaller part, interelectrode C (to CB type amplifiers).
The 572s will run cooler, have MORE plate dissipation, have MORE grid dissipation, and are a better fit. They have SLIGHTLY more C on the output side, IIRC, BUT, they let the Pi circuit eat that up.
The ONLY problem you're going to have is if you try to get 3X572b power out.
I HAVE looked at Ameritron's website, and did find there are a couple differences between the two amplifiers.
I've swapped, LITERALLY dozens (like, 4 or 5 over the years) 572s with 811s, and have ONLY had one problem, and that was with a homebrew amplifier.
SOME people have problems with Yeasu FL2100s, but that's a Svetlana issue, since russians can't copy tubes about as bad as the Chinese. Yeah, they WORK, but a 4 cylinder diesel will PULL a tractor trailer.... I'd MUCH rather have a Cummins Turbo 6!
Good luck, most of what you read on the internet is opinion. And everyone has an opinion... Some have two, like armpits, they usually BOTH stink.
Enjoy that amp and those tubes. If you REALLY want to clean up the output section, get the parasitic suppressors from Ameritron for the 572s... BUT, those won't be exact, either, since they are designed for FOUR tubes, and higher voltages.
Better yet, get ahold of Rich Measures, tell him what you've done, and he can custom design a parasitic suppressor for your amplifier. Just DON'T say shyt about it being for <<10>> meters, or he won't help... Let him know you USE the amp on 10, though, because you have to design a suppressor to work on 10 meters different than one that will never see low VHF / upper HF.
Hope that helps. Glad you took the plunge. Keep us updated
--Toll_Free