The shield should be connected to pin 2 and the connector shell at the
transceiver end. Based on your description, the shield is floating and is
thus not at system ground potential. Hence, RF getting into the cable and
keeping the PTT circuit in the base of the mike latched on.
In audio, the rule is: Shield is shield and is thus not a current carrier.
Shield should be connected to ground at the load end only. Thus the shield
from the mike to the connector is connected at pin 2 of the female mike
connector which is the same point that a ground wire from the mike is
attached. Then on the extension cable male, pin 2 only has the wire
designated as ground and shield is not connected. Then at the transceiver,
the female cable connector has the ground and shield connected together.
With this method there is a dedicated ground wire from one end to the other
and the shield is connected at one end only.
73
Bob, K4TAX
----- Original Message -----
From: "John Huffman" <hjohnc@adelphia.net>
To: "tentec" <tentec@contesting.com>
Sent: Wednesday, December 28, 2005 7:49 AM
Subject: [TenTec] Mic Extension Cable Doesn't Work
I have a new Ten Tec 706 microphone that I'm using with my Pegasus. It
works
fine, no problems.
The cord is too short, so I bought an extension cable with a 4 pin female
connector on one end. I wired a 4 pin male to the other end. I connected
the
extension cable to the Pegasus and the mike to the other end of the cable.
Audio works fine, but the PPT button and the VOX button on the microphone
won't
go off. You have to unplug the mike from the cable to get them to go off.
I
start with the buttons off, all is well. I push either button and it locks
in
the on position.
I've checked the cable a dozen times. Pin 1 goes to pin 1 and nowhere
else.
Same for pins 2, 3, and 4. None of the pins are connected to the shield
of the
cable or the shells of the connectors. None of the pins are shorting
against
each other.
This even happens when I have the "Xmit Disable" button pushed on the N4PY
program, so no RF is causing the problem.
I'm guessing it may be a ground problem with the PTT circuit in the base
of the
mike. I've tried jumpering the shells at each end of the extension cable
with
no luck.
I am at a loss to understand how extending 4 wires would cause the PTT to
lock
on.
Any suggestions will be greatly appreciated.
73 de NA8M
John
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