my buddy has just retubed an old homebrew tube amp that uses a pair of 813's, he says its grounded grid class AB2, he is getting 600w on fm with 30watt drive but was expecting more, does anybody know what power output he should be getting from this amp if its running correctly, thanks.
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
-
A Winner has been selected for the 2025 Radioddity Cyber Monday giveaway! Click Here to see who won!
813 tube help
- Thread starter bob85
- Start date
I would say that is about right for that amp without overdriving it especially on 11m.What does it run for plate voltage? Normally they run around 2000v on 813's.
Hmmm. Tube's plate is rated at 125 Watts intermittent duty, so 600 from a pair that add up to 250 is about as good as it gets. The same ratio of output to tube-rating for two 3-500Z would be 2400 Watts. Those 813s are humpin'. Big time.
Just hard to find 813s that still have a good vacuum. The last few I checked were gassy, no good.
73
Just hard to find 813s that still have a good vacuum. The last few I checked were gassy, no good.
73
Don't expect ANY more from it and I would prefer to run it at around 500 watts to make it a bit easier on the tubes.I have seen several 813 amps running 800 watts INPUT to the plates and they typically had close to 600 watts output.Don't run any more than about 350 mA plate current for the pair of tubes.