Q: Lafayette 6m rig mic connections?

[Joel Govostes]

here are some more details, if any of you Lafayette/BA officianados could
kindly take a look--
----------------------
My HE45-B schematic shows mic plug/jack pin #3 going straight thru from the
actual mic element ("hot" side) to the speech amp circuit.  Mic pin #2 goes
to cold side of mic, cable shield/chassis ground, and one side of PTT
switch.
The lead from the screen of the 7868 modulator tube (tube's pin 1/7)
connects to pin 4 on the mic jack through a 2200 ohm resistor.  All's fine
so far.

Mic pin 4, however, is shown as *shorted* with a jumper-wire to the mic pin
2, which then is grounded.

According to these conditions, keying the mic would activate the T/R relay
AND connect the the relay-energizing-voltage (mic pin 1) to mic pin 2,
which, again, goes to ground.  Therefore mic pin 4, (and 7868 screen) would
then become grounded also.  I'm not sure if this is what is supposed to be
going on.

Next, on the chassis mic JACK, my schematic shows a paralleled (.001 mfd)
capacitor & (10K)resistor coming off jack pin 4 to ground.  I don't
understand the reason for this, as pin 4 is directly grounded already as
above.

Then, finally, is the mysterious jack pin 5, which is shown connected to
the hot side of the loudspeaker.  There is NO corresponding pin # 5
connection on the mike plug.  Nothing there at all, just a blank pin.
(Huh?)

Hams being hams, someone may have gone in there and rearranged things in
the rig before, sometime since *1964*, but it's hard to say!  Anyway, I
have not been able to modulate the carrier at all,and am suspicious of the
whole mic-rig connection, since everything else in the transmitter audio
chain has checked out A-OK, and the mic, even as it *was wired, doesn't
match the diagram.

MIC: The hand mic I got with the rig (@ hamfest) is not the original
Lafayette mic, although it is hi-Z (Astatic) and works fine on my Heathkit.

Whew! -- Thanks very much for any input or suggestions on any of this...

73

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