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

[Jim]

Also... 3cx800 is only 13.5 volts at 1.5 amps each for the filament (1 
tube). Pretty small transformer.

Thanks
73
Jim W7RY

On 4/20/2019 9:22 AM, Mike McCarthy, W1NR wrote:
> 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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