I think you have asked this before, Neil. From August 6 this year, and
quoted from Garey's answer to you:
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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