Steve -
I've never tried it, but I would say the odds are not good. Aside from
the dual disc readout (perhaps not mechanical clearance), the R-4A PTO
tunes 500 kHz from 4.955 to 5.455 MHz in ten full turns. The TR-4C
tunes 600 kHz from 4.9 - 5.5 MHz in eleven turns. The linearity might
suffer if you 'retuned' 50 kHz higher. The circuitry is the same, both
run on 10 VDC derived from the +150V bus dropped by a power resistor to
emulate a true current source.
The output levels are similar, although the TR PTOs are typically a
little higher output.
If you have a TR-4C PTO you could try it, and it would probably work
although with an extra 100 kHz coverage. But if you're looking for a
replacement I'd look for an R-4A or R-4B unit. They are essentially the
same, a BJT oscillator and buffer, although R-4Bs above s/n 8000 had an
FET oscillator.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Steve Wedge wrote:
Will a PTO from a TR-4C work in an R-4A? The frequencies look the
same and it appears the supply voltage is taken from the +150V
supply. Are the dial drives different?
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