Quick answer: Yes and No.
Yes, the same crystals will work in both, but are (or should really be)
different.
The R-4 BAND oscillator is a tube, and the crystals are probably (or should be) parallel resonant,
cut for a 32 pF parallel load.
The R-4A BAND oscillator is a bipolar transistor and the crystals are (or should be) series
resonant, series resistance less than 30 ohms.
ALL T-4X(any) are bipolar transistor, series resonant.
Now, that said, either will 'work' in either, but will resonate at a 'few' kHz different frequency,
proportional to crystal frequency. I believe some of the band-to-band variations seem in some
receivers is the result of swapping crystals from unit to unit. The original specification was +/-
0.003% of marked frequency, (+/- 210 Hz @ 7 MHz,) with modern International Crystal Mfr crystals
typically much closer than that. A SET of new crystals from ICM will typically be within a few tens
of Hz from band to band.
Once again, more than anyone wanted to know, but ..... I can't help myself!
:-)
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>
Neil M Califano wrote:
Quick question: Do the R4 and the R4A take the same crystals?
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