Dick -
The AC-4 was designed to drive the T-4X Series transmitters AND the TR-4 Series transceivers. I
don't really KNOW, but I suspect that the AC-4 was designed for the T-4X, and the additional current
and reduced ripple requirements of the receiver portion of the TR-4 drove the need for more filter
capacitors. Also, since the DC-4 was used with the TR-4, with the possibility of long leads between
the two could have driven the need for more power supply decoupling.
All models used the 60 - 20 - 10 Twist-Lok cap. The 20 uF was used to just decouple the main +250V
at the input to the TR-4. The 60 uF and 10 uF were both used to further decouple the 245V and 235V
supply busses for the low-level IF and AF stages.
Electrolytic caps available when the TR-4 was designed and built, were rated at D C Working Volts
(DCWV), not as a maximum. The capacitance and voltage values you have selected will work just fine.
Tom at HayseedHamfest.com has drop-in replacements which make for a much neater job. It's pretty
crowded under the chassis.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Dick KF4NS wrote:
I plan on replacing the multi cap can with individual caps as part of
the restoration, but first I have a couple questions.
1. Why is it there to begin with since the AC-4 has already filtered
the 250V and why are there 3 different cap values? ( I already
replaced the 10mfd at 25V right at the pin8 connection of V19A with a
10 @ 50V)
2. The three values I have in mine are 60-20-10mfd at 250V so I
planned on using a 100-33-22 @ 350V but would appreciate your input on
these values I chose.
73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow!
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