[Drake] T-4XB--no output

[Jerry K]

While on the subject of fried T-4's/TR-4's, for the life of me I can't
understand why all Drake owners don't do this simple, removable,
no-holes-to-drill air flow mod for the PA cage. Take a little 3" diameter
12VDC fan, attach it to the rear uppermost outboard corner of the PA cage
with a couple of 6-32 machine screws/nuts (air flow pointing in), run the
12V leads into the chassis to a simple rectifier circuit consisting of a
1N4007 (or whatever is handy) and a 10 uF 50V electrolytic. Tap the
transmitter side of the 12VAC near the filament fuse for power to feed the
rectifier. The resulting supply to the fan will be around 8-9 VDC which will
run the fan at a whisper-quiet half speed or so, and the fan will run
anytime the rig is powered up. Assuming you don't abuse the finals while
tuning up, you will likely never have to replace another expensive 6JB6
again. There is simply no reason to NOT do this. The fan stays on the PA
cage when you remove the top cabinet cover, fits like it was made for it,
and the fan mounting holes even line up correctly with the holes in the PA
cage cover. 6JB6's run hot as a firecracker under the best of conditions,
this cures that permanently with a "non-invasive" mod. I have done this mod
on four or five Drakes with uniformly perfect results, and my TR-4 has been
running it for a couple of years with no problems. A picture of one of these
simple mods after installation is on the Bay if you look at the photos of
the T-4XB I have up for sale.
Jerry W5KP

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