I have a question for the group. What is reverse burst? And when is it used? Motorola radios.
Leroy. J39AI. -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of N1BUG Sent: Monday, May 03, 2010 1:54 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Micor PL encoder modification (TLN5731A) wd8chl wrote: > The usual method we've used is to pull it to ground when you don't want > tone with a transistor or a FET. You can remember though that, depending > on your link rx, letting the Micor encode reverse burst will close the > squelch quicker than just letting it coast. My experience is that the > reverse burst on the stock Micor encode board works on the vast majority > of radios, both Motorola and not. It worked on every Kenwood I had > except for the old TK-801. Ham or commercial. The only other radio I > have had in recnt years that it did not work on is the Yaesu VX-1R. Not > even "chicken burst" works with that radio. > > I can't say for sure, but I think that if you key it with the PTT input, > after the reverse burst delay, the tone will shut off...I could be wrong > though...I'm sure there's a simple way to do it though. A one-transistor > switch in the right place shoule do it. Thanks. It looks to me like the stock encoder supplies PL tone to the transmitter continuously, whether PTT is active or not. The only exception I can see is that for ~150 milliseconds after PTT input to the encoder goes inactive, it switches to reverse burst - then back to regular PL tone. It seems like a mod to keep reverse burst but kill the regular PL tone while still allowing the controller to keep the transmitter up (without tone) for IDs would be more complex. Unless I'm overlooking something, which I've been known to do! Squelch tails are *probably* not going to be much of an issue since I plan to use AND squelch with PL and the infamous Micor carrier squelch at the receive end of the link. That Micor squelch chip really clamps off the audio quickly if it's a full quieting signal. If there is enough of a squelch "click" to annoy me I can just add an audio delay in the appropriate spot. Paul
