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Re: [Amps] Why 2 3CX800s instead of one 8877?

To: <>, "Martin Sole" <>
Subject: Re: [Amps] Why 2 3CX800s instead of one 8877?
From: "Carl" <>
Date: Tue, 23 Apr 2019 11:12:27 -0400
List-post: <>
That is more than enough voltage to reach the then legal limit of 2000W PEP INPUT. That is also similar to the voltage and power of the Dentron DTR-2000L.

The limiting factor is the transformer and not the  tube choices.


----- Original Message ----- From: "Martin Sole" <>
To: <>
Sent: Saturday, April 20, 2019 1:34 PM
Subject: Re: [Amps] Why 2 3CX800s instead of one 8877?

I don't think the 8877 will be to lively with a mere 2400 volts on its pip. That new transformer will need to up the HT a fair bit.

Filament volts, 8877 5 volts, 8874 6.3 volts, 3CX800 13.5 volts.

Martin, HS0ZED

On 20/04/2019 06:55, Roger (K8RI) wrote:
I have been using a 76A for many years along with several other amps.

I decided I had more amps than I needed even running SO2R with backups so the 76A went up for sale. I had an immediate buyer, but as the 76 had set for a few months. I told him I wanted to run it through its paces before he made the long drive to pick it up.

You guessed it. Half power! I had used that amp for well over a decade with nary a hiccup. I go to sell it and one one of those tubes fails. One of those tubes, new costs more than the amp is worth. Now I happen to have a stash of tubes that I could modify it to use.

I would prefer to do the mod neatly, complete with a proper transformer rather than a filament transformer mounted on the back. Yes, I realize the cost. A single 3CX800 would give me what I had (it's a two hole), but going with the cost of the transformer, I might as well go with a pair of 3CX800s, or a single 8877. If I do the conversion to legal limit, I will have as much, or more into the amp than what I can get out of it, so I'll probably keep it and sell my Quadra.
Of course the third option is to just sell the 76 as is.

Other than the replacement cost and availability, Is there a reason for not using a single 8877 Vs a pair of 3CX800s? Using new tubes the 8877 would have been the economical choice, but I understand that the prices have gone up. Tube prices for legal limit amps are beginning to make the new SS legal limit amps look better all the time.

I also have a completely restored HT33B (Sans 2 panel screws) with a ceramic 8295A and 3 spare ceramic 8295As . Last time I used it it had full power, but that was prior to 1997

73, Roger (K8RI)

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