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Author Topic: Mixing tubes in Ameritron  (Read 594 times)

Offline RadioPushka

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Mixing tubes in Ameritron
« on: February 17, 2022, 0521 UTC »
Is it ok to mix a 572b tube and a G811 tube in the same amplifier? or bad idea, and I need to save up for 572b?
Thank you!
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Offline RobRich

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Re: Mixing tubes in Ameritron
« Reply #1 on: February 17, 2022, 1524 UTC »
There are slight capacitance differences and distinct gain differences between an 811a and a 572b. I would suggest not mixing them, as there could be a resulting distributed loading imbalance between the mixed tubes.
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Offline RadioPushka

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Re: Mixing tubes in Ameritron
« Reply #2 on: February 19, 2022, 0248 UTC »
Yeah, thank you!
That's what I have noticed too when I switch a single 572b and a single 811A. I want to make sure.
Also, I have this issue, I have the load all the way down to 0 and anything slightly above that the output drops significantly. I have a 1.1 swr on my vertical antenna. Also, at this low load setting the tubes glow, they glow harder when I set it higher. Do you know how I can get it to where the tubes are not glowing and the power is not lost due to a tuning mismatch? I am operating at 6920 khz and the band setting is set to 40 meters.
"Is pushka his technician?" - Radio Ga Ga
 "Get better modulation, stupid" - Radio Genix
а нука, какая песня сейчас играет на Радио?
https://radiopushka.site/?page=voteforsongs
вот пожалуйста!
можно еще закзать на прослушку;)

Offline Polar Bear

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Re: Mixing tubes in Ameritron
« Reply #3 on: February 22, 2022, 2050 UTC »
Always use matched tubes..

There are many fine articles online - I would suggest that you read them..

Offline radiogaga

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Re: Mixing tubes in Ameritron
« Reply #4 on: February 23, 2022, 0154 UTC »
Also, I have this issue, I have the load all the way down to 0 and anything slightly above that the output drops significantly. I have a 1.1 swr on my vertical antenna. Also, at this low load setting the tubes glow, they glow harder when I set it higher. Do you know how I can get it to where the tubes are not glowing and the power is not lost due to a tuning mismatch? I am operating at 6920 khz and the band setting is set to 40 meters.

Do you know how to properly tune a tube amp to resonance?
Does your plate current dip at all?
Tubes in amps are supposed to have glowing plates...just not too much for too long.... ;)

Offline RadioPushka

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Re: Mixing tubes in Ameritron
« Reply #5 on: February 23, 2022, 0321 UTC »

Do you know how to properly tune a tube amp to resonance?
Does your plate current dip at all?
Tubes in amps are supposed to have glowing plates...just not too much for too long.... ;)
Yes, I get a resonance point out of the tunning range. I have the load at 0 and that's not enough, it needs to go under 0 for resonance. and the dip in plate current Is very small when i adjust the plate knob. yeah they glow when mistuned. I have tuned it before and it worked. It just won't tune into a perfect match on 6920. It can tune when the swr is over 1.5
"Is pushka his technician?" - Radio Ga Ga
 "Get better modulation, stupid" - Radio Genix
а нука, какая песня сейчас играет на Радио?
https://radiopushka.site/?page=voteforsongs
вот пожалуйста!
можно еще закзать на прослушку;)

 

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