3CX800's will go into the same sockets and have similar high voltage
and current requirements to the originals so it matches the tank circuit
better. Going full legal limit might require rebuilding the output tank
to match the difference in impedance.
Mike, W1NR
On 4/19/19 7:55 PM, 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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