Henry -
The R-4C probably needs only a good cleaning/DeoxIT treatment.
Primarily the rotary switches, but also the tube and crystal sockets.
Go through with a screwdriver and check all chassis hardware, tube
sockets, PC boards, terminal strips, shields, essentially every screw
that goes into the chassis. If not tight, tighten firmly, if tight,
loosen slightly and retighten. This should take care of most problems
that occur in long term storage.
Follow the same process in the T-4XC, then troubleshoot what remains, if
anything!
I believe the screws in the bottom of the AC-4 are 6-32 x 1/4" pan head.
The 6JF6 is a 'potential' replacement for the 6JB6. It is the same
base, slightly higher transconductance, BUT considerably higher
interelement capacitances. So they 'may' work, especially on the lower
bands, but neutralization may be problematic. It may be necessary to
increase the value of C65 to bring the adjustment in range.
Don't hesitate to post here if you have more questions!
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>
Henry Vredegoor wrote:
Hello All,
I am new to this list, but reading it for some time now.
I'm in the process of setting up/restoring/repairing a Drake 4C line:
R4C, I own this receiver for 35+ years, proved defective when I
recently switched it on after some years of storage
T4XC, bought recently, sold as being defective
MN4, working OK
MS4, working OK
AC4, currently being refurbished by me
As all items were bought separately, I'm missing bits here and there,
like the screws that mount the AC4 PSU in the MS4 cabinet from the
bottom side.
I assume they are non-metric (M3/M4 do not fit).
Can anybody here on this list please tell me what thread/size they
are, so I can order the right screws?
I could not find any info on this in the documentation.
I too have a second question.
With the AC4 came four spare tubes, supposedly usable as a replacement
for the 6JB6A power tube, type 6JF6
Is this a direct "drop-in" replacement for the 6JB6A in the Drake T4XC
or would I have to change (many-) things in the PA circuit
(neutrodynisation etc.) to be able to use these?
Any help appreciated.
73's,
Henry - PA0HJA
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