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

[Martin Sole]

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)
>