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Re: OT2m with a Motorola GP300

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  • wbirriel
    Thank you to all, I managed to make it work by soldering a 10Kohm resistor from pin 3 to pin 1. I found through some obscure site that you have to add
    Message 1 of 5 , Aug 27, 2010
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      Thank you to all, I managed to make it work by soldering a 10Kohm resistor from pin 3 to pin 1. I found through some obscure site that you have to add resistance to ground from the mic line and it activates the PTT without distorting the sound. They didn't say what resistance but I figured 10 Kohm should keep distortion to a minimum and I have to say that so far so good.

      73's

      Walter
      KJ4TUW

      --- In tracker2@yahoogroups.com, "k7ybz" <k7ybz@...> wrote:
      >
      > Sorry,
      > I should have looked this up before my last post.
      >
      > Here is a link to the mic schematic for GP300:
      > http://www.batlabs.com/images/gpspkmk.gif
      >
      > Here is a link to a service cable for the GP300:
      > http://www.batlabs.com/images/gp300svc.gif
      >
      > What I cannot determine is if the PTT for the service cable is HIGH (Some Voltage) or LOW (gnd).
      >
      > You will have to do more research and might have to do a little experimenting based off the service cable schematic.
      >
      > The OT2 only has a 0.1uf blocking cap rather than the 1.0uf for the service cable and the resistor for the HT is only 2.2k vs the 33k for the service cable. The PTT for the OT2 goes to gnd.
      >
      > Larry
      > K7YBZ
      >
      >
      >
      >
      > --- In tracker2@yahoogroups.com, "k7ybz" <k7ybz@> wrote:
      > >
      > > The OT2 does have a 0.1uf blocking cap on the mic input. With the separate PTT wire you should not use the HT jumper.
      > >
      > > For the colors listed below:
      > > RED -- SPEAKER -- OT2 PIN 5
      > > WHITE -- MIC ---- OT2 PIN 1
      > > BLUE -- PTT ----- OT2 PIN 3
      > > BLACK -- GND ---- OT2 PIN 6
      > >
      > > If you got the cable from Argent Data, Scott does note that some of the cables came with the blue and black wires swapped. So you will want to check the wiring from the pins to verify the connectivity.
      > >
      > > Larry
      > > K7YBZ
      > >
      > > --- In tracker2@yahoogroups.com, "Alan" <alan@> wrote:
      > > >
      > > > Don't think mot combines PTT on tx audio line. They often will put regulated + voltage on Mic line to power hand mics that need power. A small cap will isolate the +v off the mic hi line. OT2 might already have a cap on mic input, not sure.
      > > >
      > > > Red - Speaker
      > > > White - Mic
      > > > Blue - PTT (if used)
      > > > Black - Ground
      > > >
      > > > Argent has a cable
      > > > http://www.argentdata.com/catalog/product_info.php?cPath=21&products_id=71
      > > >
      > > > Alan
      > > >
      > > >
      > > >
      > > > --- In tracker2@yahoogroups.com, "wbirriel" <wbirriel@> wrote:
      > > > >
      > > > > I tried using the OT2m with a Motorola GP300. The GP300 and the P110 use the Mic output also for the PTT. I proceeded to set the HT jumper just like it says on page 7 of the Tracker 2 manual to enable PTT signaling through the output line, after setting the jumper the PTT was stuck on. Nothing made it set to off except removing the jumper. Does anyone have any idea on what I should do to make it work properly?
      > > > >
      > > > > Walter
      > > > > KJ4TUW
      > > > >
      > > >
      > >
      >
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