[AMPS] MLA-2500 MOD FOR GG 4CX-800'S CONFIKGURATION
Fri, 4 Aug 2000 19:48:13 -0500
> >I have an MLA-2500 with soft tubes. Seeking information on modification
> >using a
> >pair of 4cx800 tubes in grounded grid.thus eliminating a seperate bias
> >supply and screen supply.
> You will need a high pressure centrifugal blower. The tubes need to be
> relocated near the Tune-C. A small 6v transformer is needed to increase
> the heater potential.
> good luck, Mel
You really only need one tube, as it will put out as much as the pair of 8875's.
To take advantage of the potential of a pair will be nullified by a power supply
melt-down. It is easy to get screen and bias voltage with a few simple mods
on the existing transformer. Running tetrodes @ zero bias and screen voltage
went out with the glass tube era.
Instead of relocating the tube near the tune C, why not add a small profile 500 pf
vacuum variable where the second tube was? This will kill two birds with one
stone....better lay-out, and removal of all those door knob padders that
are marginal @ 1500 watts.
Two Rotron fans in tandem might just do the cooling trick. Some heat sensitive
paint on the tube will tell the tale.
FAQ on WWW: http://www.contesting.com/FAQ/amps
Administrative requests: amps-REQUEST@contesting.com