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@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 _______________________________________________ App_rpt-users mailing list App_rpt-users@ohnosec.org http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users To unsubscribe from this list please visit http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.