[App_rpt-users] Wiring a GM300 to a RTCM

[R. Wayne]

Shouldn't I also have the RADIO COS/PL VALID pin hooked up to CTCSS LOGIC input on the RTCM? What would the connection be?

From: Sam Nabkey 
Sent: Saturday, June 20, 2015 6:05 AM
To: R. Wayne 
Cc: Allstar app_rpt-users Group 
Subject: Re: [App_rpt-users] Wiring a GM300 to a RTCM

The GM300 either presents de-emphasized squelched audio or non de-emphasized discrimator audio at pin 11 depending on the position of the jumper inside the radio.

The squelch circuit inside the RTCM is superior to the squelch built into to GM300.   Properly calibrated,  there isn't any burst.  

I hooked pin 8 to the CTCSS pin on the RTCM so I can use the radios decoder.  I also don't use the RTCM for encoding CTCSS.   I let the radio do it.

Both those links should get you rolling.

Your mileage may vary...  Caution!  Beverage in this container may be HOT!!

Go have some fun!!

On Jun 20, 2015 8:30 AM, "R. Wayne" <allstar at controlservers.net> wrote:

  But, but, but... it helps to know the words to google! I googled RTCM GM300 and didn’t get the links you did. But I’m here to learn!

  Not sure of this line.

  GM300 Pin 11 - RTCM Pin 3 - Rx Audio JU 551 inside the GM300,  in position A gives FLAT (not De-emphasised) audio out pin 11.We want to use the RTCM's internal Squelch.

  So pin 11 on the GM300 already has the flat audio we seek. But Jumper 551 to the A position is the best audio? OK. Buy why the RTCM’s squelch? I know that we’ve had problems with squelch tails...

  From: Sam Nabkey 
  Sent: Saturday, June 20, 2015 5:06 AM
  To: R. Wayne 
  Cc: Allstar app_rpt-users Group 
  Subject: Re: [App_rpt-users] Wiring a GM300 to a RTCM

  Hello.. 

  GM300 Pin 11 - RTCM Pin 3 - Rx Audio JU 551 inside the GM300,  in position A gives FLAT (not De-emphasised) audio out pin 11.We want to use the RTCM's internal Squelch.

  GM300 Pin 8 - RTCM  Pin 4 - CTCSS Input
  GM300 Pin 5 - RTCM Pin 2 - TX Audio
  GM300 Pin 3 - RTCM Pin 7 - PTT
  GM300 Pin 7 - RTCM Pin 9 - Gnd

  RTCM Info - http://www.micro-node.com/thin-m1.html
  GM300 Info- http://www.batlabs.com/gm300.html

  Google is your friend.  

  Have fun!!!  



  On Sat, Jun 20, 2015 at 1:48 AM, R. Wayne <allstar at controlservers.net> wrote:

    I’ll confess that I am new to this part. It was dumped on me without warning and that’s OK. Time to learn a few things. I have a GM300 that is going to be a remote base and a cable purchased from eBay that is prewired for the GM300 side. I understand (I think) that TX goes RX, RX goes to TX, GRND to GRND – but now for PTT, COR and CTCSS. I wonder if some could push me over a cliff – I mean in the right direction. I have no documentation on the RTCM.

    Thanks, R. Wayne

    The RTCM connections are:

    DB9-Female

    1 Vin (12v)
    2 TX Audio
    3 RX Audio
    4 CTCSS
    5 GND
    6 GND
    7 PTT
    8 GND
    9 GND

    The GM300 cable (and radio) connections are:


    Pin #

    2     MIC                                          BLU
    3     PTT                                           WHI-BLU
    4     PROGRAMMABLE OUTPUT     BRO
    5     FLAT TX AUDIO                        GRN
    7     GROUND                                  WHI-GRN  
    8     PROGRAMMABLE I/O (COR ?)ONG
    11   RECEIVE AUDIO                       WHI-ONG
    14   PROGRAMMABLE I/O              WHI-BRO
    15-16  Jumpered to enable internal speaker

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