K3 8 pin mic wiring to avoid "pin 1" problems...how best to...??

[VK7JB]

Hello Group,

I'm rewiring an 8 pin mic connector FROM an Icom configuration TO a  K3 pinout.

Wiring the Mic + and PTT lines is straight forward.  But how best to wire the PTT GND,  Mic - and Cable shield connections is bothering me.

I'd like to wire the Mic - and cable shield  to avoid the risk of "pin 1" problems and RFI etc, but if I interpret  the schematic and mic pinout info for the K3 correctly,  front panel mic pins 7 & 8 are wired in common with the chassis.  

So, am I correct in understanding that on the K3, there's no way of seprating Mic-, PTT GND and cable shield/chassis - ie they're all bonded in common?

If this is correct, should I simply  wire PTT GND to pin 7 and  Mic- and cable shield to pin 8.  (But they are all connected together in the rig).

In other words,  is this wiring pinout  the most appropriate?

Pin 1 ----> Mic +
Pin 2 ----> PTT
Pin 7 ----> PTT GND
Pin 8 ----> Mic - and cable shield.
(pin 7 and 8 being bonded internally anyway)

Thanks for any clarification.  It's possible I'm over-thinking this! :)

73,
John
VK7JB

[Nr4c]

I've wired several K3, Kenwood and ICOM mics and Kenwood and K3 are
very similar.  I think you'll find that the mic and PTT are the same,
with mic being on Pin 1 and 7, PTT on 2 and 8.  Cable shield is usually
tied to pin 8 as well.

...bill  nr4c


On Thu, 2 Jun 2011 06:04:55 -0700 (PDT), VK7JB wrote:

> Hello Group,
>
> I'm rewiring an 8 pin mic connector FROM an Icom configuration TO a  
> K3
> pinout.
>
> Wiring the Mic + and PTT lines is straight forward.  But how best to
> wire
> the PTT GND,  Mic - and Cable shield connections is bothering me.
>
> I'd like to wire the Mic - and cable shield  to avoid the risk of
> "pin 1"
> problems and RFI etc, but if I interpret  the schematic and mic
> pinout info
> for the K3 correctly,  front panel mic pins 7 & 8 are wired in common
> with
> the chassis.
>
> So, am I correct in understanding that on the K3, there's no way of
> seprating Mic-, PTT GND and cable shield/chassis - ie they're all
> bonded in
> common?
>
> If this is correct, should I simply  wire PTT GND to pin 7 and  Mic-
> and
> cable shield to pin 8.  (But they are all connected together in the
> rig).
>
> In other words,  is this wiring pinout  the most appropriate?
>
> Pin 1 ----> Mic +
> Pin 2 ----> PTT
> Pin 7 ----> PTT GND
> Pin 8 ----> Mic - and cable shield.
> (pin 7 and 8 being bonded internally anyway)
>
> Thanks for any clarification.  It's possible I'm over-thinking this!
> :)
>
> 73,
> John
> VK7JB
>
>
>
>
>
>
>
> --
> View this message in context:
>
> http://elecraft.365791.n2.nabble.com/K3-8-pin-mic-wiring-to-avoid-pin-1-problems-how-best-to-tp6431057p6431057.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[Don Wilhelm-4]

  The "pin 1" problem is not a function of the cable wiring, but of the
equipment that it plugs to.
To avoid a pin 1 problem, the shield path for the connector should be
connected to the equipment enclosure.  That was easy when we had
connectors that mounted on the enclosure, but becomes difficult without
extra measures if the connector is mounted to a PC board instead of to
the enclosure.

Connect the PTT return and the AF return (mic shield) to pins 7 and 8,
and if there is an overall cable shield, it would best be connected to
the shell of the mic plug.
That is about all you can do.

73,
Don W3FPR


On 6/2/2011 9:04 AM, VK7JB wrote:
> Hello Group,
>
> I'm rewiring an 8 pin mic connector FROM an Icom configuration TO a  K3
> pinout.
>
> Wiring the Mic + and PTT lines is straight forward.  But how best to wire
> the PTT GND,  Mic - and Cable shield connections is bothering me.
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html