[Amps] 3-500zs to 8877

[Donald Fox]

Apologies in advance if this made it the first time around. 
I am resending because I don't think it did.

 To start:

Many thanks for all of the informative responses to date. 

I will try to answer them as best I can while remaining brief if possible. I have a pretty good understanding of most common low tech amps like the Henrys and Heathkits etc. 

I agree that the 8877 is way more expensive if we are talking about new, but as we all know they are readily available for ~$300 as medical pulls in both 3CX and 3CPX form.

I too like the glow of the glass bottles which one does not get to enjoy from the ceramic counterparts.

Recalling that Henry likes to run their filaments in series, my present xformer is 10 volts at 15 amps which would be great for a pair of 8877s, but not in my game plan.

Agreed that the 3-500, 3CX1200A7, 3CX1200D7, and 3CX1500D7 all share the same socket as well as the instant on feature. They also are quite pricey (excepting the 3-500), and require more drive.

The instant on feature is not a big issue for me, as I am not a big DX hound, and usually have the amp ready to go while in the shack anyway.

My research says that the Henry 3K console uses 12 volt control circuitry like my 2K does. 

Regarding plate voltage, my 2KX is unusual in that a previous owner apparently lost the plate xformer, and replaced it with the unit from the 5K. 
Thus, my CW Ep is 3800 and the SSB Ep is 4400. I have seen 4k out of a 5K with 150 watts in, so I know there is plenty of room there.

Experimentation has shown that 120 watts in will produce 1500-1800 watts out in SSB, but plate input goes up a bunch for little change in output suggesting possibly an unfriendly plate circuit impedance at that level.

I do believe I can do the change properly and without any 'hacking" if it can be done without any changes other than retuning the input circuits along with the attendant socket, filament xformer, and cooling changes.

For as much as I use it, those of you recommending leaving it as is are thinking well. 

We all know as well that any power increase will make little difference on the other end except for the electric bill.

I have owned many 572B amps along with many 3-500z models. The only ceramic model I have had a few of are the SB-230. 

I remember when 3-500zs were $85, and the 8873, 4, and 5 tubes were $50. 

What a closet full of those would be worth today!!!!!!


                                                               Don