Thank you Jon Rorke for a well thought out reply. You hit the nail on the head and I haven't seen anything on this topic. That's why I asked. I have a Motorola MSF's and a Motorola MSR that have a VCO input and I was curious how to interface to it for simulcasting. I also have Motorola GPS receiver modules that plug into the repeaters. I sincerely apologize if some find this message thread as stupid, based on private emails, but not knowing where or who to ask I thought that this was the correct mailing list. Is there an easier way that as a noob with Allstar I just don't know about yet? If I read you correctly any GPS that provides a 1pps output provides the VCO locking in some form but is there a tutorial or a HOWTO that discusses this? I have a TKR-850 that I want to use as well and I'm not aware of a VCO input. If ya'll could just point me in the right direction I'd be much appreciative. I appreciate your helpful answer. Thank you. [Quote] uh,.... what? Seriously? (I know I'm working on cup #1 and it's not quite 6am... I had to read this a couple of times to 'really' see this question and it's just as silly, every time!) [/QUOTE] Message: 1 Date: Tue, 25 Feb 2014 08:49:33 -0500 From: Jon Rorke <jrorke@cogeco.ca> To: app_rpt-users@ohnosec.org Subject: Re: [App_rpt-users] VCO Locking Message-ID: <530C9F6D.5060402@cogeco.ca> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" If you talking about synchronizing transmitters for simulcast, then that is done with an external reference oscillator (instead of the transmitter's internal ref Oscillator) at each site and that oscillator is locked by a GPS receiver to achieve very accurate frequency. Typically the external oscillator operates at some frequency like 16, 12.5 or 10 MHz but can be locked the GPS that puts out a 1 pps signal. Perhaps others can elaborate further. Jon VA3RQ