Ameritron AL811 / AL811H

[YardDog]

Well I'm about to show my ignorance so bear with me for a few questions.
#1 Ameritron advertised their 811 tubes as fully neutralized and ready to rock. Many other manufacturers never mention this. Do the tubes have to be neutralized for my 811H?

#2 I've read that using 572b instead of 811 tubes is preferred in an 811h. They won't give more power, but are more robust. But I've also read that using 572b puts more strain on the rest of the amp. Is this true?

#3 My SB-200 has the original 572b RCA tubes that are fine, but I want a spare set on the shelf. I've never read anything about them being neutralized, but should they be?

#4 If I had tubes that were neutralized and put them in an amp that didn't require it, are bad things going to happen?

I don't work on amps and have no desire to know all the intricacies. I just buy them and use them. I'll pay someone else to handle the rest.

 

[nomadradio]

To get old school 811A performance today, you need to upgrade to 572B.

Been my advice for decades. Yeah, 811A tubes are cheap, and good 572B tubes are getting tougher to obtain.

Doesn't change the physics of the problem.

73

 

[nomadradio]

using 572b puts more strain on the rest of the amp. Is this true?

No. When operating at the lower voltage limit of the 811A it behaves exactly like one in all respects other than thermal robustness.

Neutralization sounded like a good idea, but all the 60s, 70s and 80s designs leave it out. Wish I could explain the difference, but the Yaesu, Heathkit and Dentron amplifiers are reasonably stable without it.

I'm sure Tom knew what he was doing including neutralization in the Ameritron designs, but I'm at a loss to explain why the older products got away without it.

73