On 9/14/2015 1:25 PM, Don Wilhelm wrote:
if it were mine, I would preserve the balanced configuration through
your switchbox and only connect the mic low to ground at each radio's
plug.
*Absolutely* ... connect the *shield* of the XLR cable to chassis and
switch both mic + and mic - carrying both wires all the way through to
the transceiver. At the transceiver the shield should be connected to
the *shell* of the Foster plug which should, in turn, be bonded to the
*case/chassis* of the transceiver.
Connecting a shield via a connector pin to a circuit board then via a
"long" trace back to the chassis/case (power supply return), is the
very definition of the "pin 1 problem." Every amateur transceiver has
a pin 1 problem and most third party accessories have to deal with that
issue in their own (typically non-standard) way.
73,
... Joe, W4TV
On 9/14/2015 1:25 PM, Don Wilhelm wrote:
Dan,
Jim Brown K9YC or Joe W4TV would be a better resource than I am, but if
it were mine, I would preserve the balanced configuration through your
switchbox and only connect the mic low to ground at each radio's plug.
73,
Don W3FPR
On 9/14/2015 1:12 PM, Dan Atchison via Elecraft wrote:
I am building a switchbox to allow use of a Heil PR-781 microphone to
be used by my K3S and K3, the switchbox using XLR connectors. I note
that in the Heil XLR cable ended in an 8-Pin Foster has mic low (-)
tied to ground and (+) tied to mic high.
Knowing that the XLR pin 1 should be chassis ground, my question is,
"At the switchbox, should I tie XLR pins 1 and 2 together and only
switch XLR pin 3 between radios?" IOW, should XLR pins 1 and 2 be
chassis grounded or should I chassis ground pin 1 and switch both XLR
pins 2 and 3?
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