Another place to look for rx audio is the top side of the volume pot. Some are squelch gated and some aren't, but it should be constant level and decent frequency response.
Also, be aware that if you are using tone decode on the rx, the busy light may not follow the tone decode function. Some radios "flash" or "blink" the busy light when receiving a signal without the programmed ctcss/dtcss. Mike/W5JR ---[Original Message]--- From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Jul 3, 2008 1:49:32 PM Subject: Re: [Repeater-Builder] RELM SMUxx Link Radio? Thanks for the ideas... I'll have to check on the Relm I have and see if she has a 'busy' indicator, thinking it does, should have some 4N25's or similar laying on the bench somewhere from another project, fortunately the controllers aren't fussy and can use either + or - for COS. I was trying to avoid using the speaker audio but it looks like that might be the easiest choice right now unless I can find something better between now and next week. Thanks, Dave - N0TRQ -- Every electronic device is manufactured with smoke stored deep inside... only a true genius can find a way to set it free. On Thu, Jul 3, 2008 at 9:18 AM, Jim Brown <[EMAIL PROTECTED]> wrote: > I have had good success in obtaining a COS signal from an 'unknown > circuit' by opening the lead to the front panel LED that indicates receive > activity. Place the diode of an opto isolator in series with the LED and > then use the transistor section of the opto isolator in your circuit as the > COS signal. You can use the transistor to pull up a resistor to a positive > voltage if you need a positive going COS ( with the other end grounded) or > you can pull a resistor to ground for a negative going COS (with the other > end connected to a plus voltage ). > > I have no idea if your radios have this front panel activity LED, but most > do. The PTT and mic inputs are pretty straightforward, and the speaker > audio can be used in a pinch, if the knob is removed from the audio gain > control to discourage folks from 'tweaking'. > > 73 - Jim W5ZIT > > > --- On *Tue, 7/1/08, dakaratcaptivereefing <[EMAIL PROTECTED]>* wrote: > > From: dakaratcaptivereefing <[EMAIL PROTECTED]> > Subject: [Repeater-Builder] RELM SMUxx Link Radio? > To: Repeater-Builder@yahoogroups.com > Date: Tuesday, July 1, 2008, 12:42 PM > > I've recently been tasked to link a couple of VHF repeaters with a UHF > link.. not too difficult, however the link radio's provided are Relm > SMUxxxx's, they are all programmed and ready to go. > > I'm just having trouble finding any good docs on locations to tap for > Rcv/Tx audio and maybe COS in these radios. > > On the plus side, I've bought an extra controller for myself and have > an extra mobile rig of the same model to experiment with before > tackling the repeaters... might as well make a mobile remote base for > my RV to play with while out fishing etc... > > Can anyone recommend a good starting point or some docs? Even better I > like pics :) > > Thanks > Dave - N0TRQ > > > > --
