Okay...
I put the Shure 450 away for now, as I'm not going to try to tackle 2
problems at the same time.
Now, on to the TT 705 mic. I have checked the wiring, and made sure
all connections are solid and all
solder points are solid. All check out fine. When the TT 705 is in
PTT mode (via the switch at the base)
and the 9V battery is in, I get 60 OHMS of resistance with the PTT
button depressed and infinite resistance
with the PTT switch open. Is this acceptable?
And, as a reminder, if I attach the 705 to the radio with the 705
switched to PTT, the radio locks into transmit
mode. Is something wrong with the circuitry in the microphone? I'm
not sure what impact the NPN transistor
would have on the resistance between the PTT and ground pins in the
connector. I'm used to open and
closed switches, which have almost no resistance when closed.
Thanks!
John
K2JNC
On Aug 17, 2009, at 9:07 PM, Richards wrote:
Gee... I wonder if there is more than one issue here...
Have you checked the wiring diagram on the Shure mic?
Also same question about the TT mic?
I am thinking the one mic may be wired incorrectly and
the other may have another issue. I would trace all wiring diagrams
out
and see if there are differences in the way they are wired. That
might
eliminate some possible problems.
After you have traced the microphone wiring on both microphones, you
will have either identified a problem, or eliminated a possible
problem.
After checking the wiring diagrams... I would check each microphone
with
a continuity tester to see if the switches are going on and off as
they
should. Again... just a basic check to see if you can identify a
problem in the microphone, or eliminate that as a possible problem.
After checking wiring and switch functionality, you can then look to
relay problems in the rig. But these seem easier to check to me and
you will either ID a problem, or eliminate some possibilities. These
seem easiest to do first.
Just a thought...
============== Richards - K8JHR ===============
John Callari wrote:
It seems that something is wrong with the PTT as controlled via the
PTT/VOX button on the face of the radio.
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