[Elecraft] K3/K3S Pin 1 question

[Joe Subich, W4TV]

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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