Pete -
There were two versions of the T-4XB transmitter, but the C129 / C140
was the same in both. 60uF @ 250 and 10 uF @ 10V. A direct
replacement is available from <www.hayseedhamfest.com>.
Both schematics are on my Service Supplement CD for the B-Line (along
with all three of the R-4B). You might find the photos of the
underchassis and all pc boards helpful in 'restoring' the original! :-)
The ID of the schematic has the 'effective' s'/n as the last five
digits. An ID ending in 16159 covers s/n 16159 and up.
--
73, Garey - K4OAH
St Charles, IL
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Pete Juliano wrote:
I am in the process of refurbishing a T4XB that has been significantly
modified. (This is more like a detective story and whodunit or done what?)
The can electrolytic which I believe is a combination of C129 and
C140 was removed from the T4XB and a metal plug was fitted to the
chassis.
I have a manual I downloaded and in the spare parts list is the
following entry for a combination electrolytic
C129 = 20 Mfd @ 250 Volts
C140 = 10 Mfd @ 25 Volts
The schematic from the same downloaded manual shows C129 as being 60
MFd. In this T4XB, C129 has been replaced with a 60 MFd @ 350 Volt
radial electrolytic that was cable tied underneath the chassis to hold
it in place.
Thus two questions:
1) Which is the correct value? (I would think having the larger value
of capacitance is more desirable especially since this is in the plate
circuit of the 12AX7.)
2) I have no problem with having something different in the radio so
long as it is electrically correct. But is there any chance the dual
electrolytic originally installed is available from some source. The
can as originally installed appears to have no insulating ring and the
three ears on the can were simply bent over and soldered to the
chassis. Or is on the "unobtainium" list?
Thanks in advance.
Pete N6QW
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