Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Guy -
The AC-3 was designed for the TR-3, before the "twins" existed. The
speaker output of the TR-3 was brought out of the backshell of the AC-3
connector on a short RCA jack "pigtail" so the transceiver could be
unplugged from a single connector when used mobile. It was designed as
a mobile transceiver, most hams at that time still used separate rx and
tx at home. There was no provision for keying or ALC for an external
linear amplifier for the same reason! Most hams weren't running linear
amps mobile either..... :-)
When the R-4/T-4X came along, the AC-4 was designed to include the ALC
and VOX connectors, and the speaker lead came directly out of the
receiver. Pin 3 is the ALC input to the T-4X, (referenced to chassis
ground,) and Pins 5 and 8 are the ISOLATED N.O. relay contacts for the
VOX or external amplifier keying. Pin 12 (ref to chassis) is the
speaker output of the TR-3/4.
I got my first R-4/T-4X with an AC-3 because the AC-4 wasn't out yet,
and I just opened the AC-3 connector and moved the speaker pigtail to
the ALC Pin 3, and added a two pin connector on a pigtail to Pins 5 and
8. Your guy worked a lot harder at it!!
Bottom line, you have a TR-3 power supply modified to drive and control
a B-Line. Not a problem, the AC-3 is perfectly capable, and essentially
identical to the AC-4 except for the "added features" on yours.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Guy Giacopuzzi wrote:
Dear Drake list members,
I'm a bit new to Drake radios, and recently purchased a B-line,
with an AC-3...after reading the scary stories about bias supply
failures, I decided to recap the power supply prior to powering up the
transmitter... before recapping I did a little looking...I found some
mods on the AC-3 (three of them, what I think are mods)......was
hoping someone could explain them...
On the rear apron, there's (1), a female RCA jack on the apron
labeled "agc" and (2), a two pin female jack labeled "antivox".
Also, there's (3) a second (extra) cable coming out of a gromet lined
hole (the hole was drilled right under the "n" of "caution") and this
cable is rather expertly tied to the main cable and goes into the
Cinch/Jones female plug. Both the added female jacks go to the extra
cable. Curiously, the extra cable has but one wire actually attached
to the internal wiring of the power supply...and that one wire goes to
a ground lug. The "anti-vox" goes to pins 5 and 8 in the Cinch/Jones
plug...The "agc" goes to pin 3. Pins 3,5 and 8 are the only unused
pins in the plug
Oh, yes. There's another, separate, cable: It has a two pin
male (which appears to fit the "anti vox" female" with a female RCA on
it...it's about 14" long. When examining the schematic for the AC-3,/
none /of the above appears on the schematic. When looking in the
transmitter manual, none of these connections or cables show up in the
connection diagrams between the receiver, transmitter, and AC-3. It
appears, on the surface, the previous owner wanted both anti-vox and
agc outputs on the back of the AC-3...but why? Any ideas?
Thanks,
Guy,
WA6OQQ.
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