[Amps] 4cX5000 amplifier

[Clark Turner]

I have acquired an amplifier built by my Elmer (SK).  The weather is 
starting to cool off so that means I can work in the garage. Its getting 
close to rebuild time for this amplifier. What I know:

The amplifier has a 4CX5000 with one brand new tube for a spare. The 
builders notes are as follows:

3 amp plate transformer

50UF at 10KV cap

8400 volts B plus unloaded and 6700 volts B plus at 5KW Key down CW

It does have a low/TUNE mode that produces 5KV unloaded.

Screen supply is 1050 volts as measured. Has a transformer, choke, cap 
and 12 !!!  VR tubes for regulation

Amplifier is Grid Driven with Feedback and has no tuned input.

Output network is large vac variables with plug in coils. I have the 
coil for 40 as it was installed.

His notes say 8 watts input would produce 5KW in CW.

The current tube has failed and in the process blew the screen current 
meter out. I plan a full rebuild with new Plate choke, Bypass and block 
cap, New coil with 20/40/80 taps.

I could update and repair this amp and use as is or convert to Triode 
and rip the screen supply and all 12 VR tubes out. Or keep the screen 
supply and remove all those VR tubes. Most of my gear is older and will 
have way more than 8 watts drive.  I could swamp the input..

How will a 4cx5000 work in GG?

I have thought about also switching to a 3cx3000 tube and just selling 
the 5000s off.

Thoughts on what to do to this old 80s amp?

KE7TRP


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Clark Turner
480-695-2898