There's a lot of history about the squelch circuits on the various repeater receiver boards related to Hamtronics, Kendercom, Spectrum and Hi-Pro... etc, etc. There are many different types of squelch circuits but most of these circuits use a common design and operation theme.
A lot of Scanners of a certain past era have the same type of IF and Squelch layout as found in the above product names. I have lots of notes, references and engineering information for many of the common Narrow Band IF Chips like (but not limited to) the MC3361, MC3357, MC3359 and a fair number of discreet circuits. Most of the basic squelch circuits in Pre-Built and Kit Amateur FM Receivers (found in repeater operation) work pretty well (with some exceptions both ways), some are better, faster and improved over the basic operation (circuit) described in the Motorola Data Book (for these devices). You just have to figure out what type of squelch operation you really want. If the circuit you have will support simple changes/mods to reconfigure the operation more toward your liking... I might have or know where to easily obtain that information from my files or references found the internet. As an example a lot of early Radio Shack Scanners have/had really mushy squelch operation, which can modified to be less annoying. If you're running a repeater controller with an audio delay module in front of the audio... much of the squelch speed hype is mute (not worth it) if the delay chops out the crash noise. You typically need to only ensure the COR/COS function works as desired. So... got milk? s. --- In [email protected], "Mike Besemer \(WM4B\)" <mwbese...@...> wrote: > > Anybody got any suggestions about fixing the squelch circuit? (Spare me the > 'get a REAL repeater' comments please!) > > > > Is the MICOR squelch still available? Anybody done it to one of these? > > > > I've got 3 of these beasts (2 in service and one spare) and the squelch on > one of them in particular is pretty lousy. > > > > 73, > > > > Mike > > WM4B > > > > From: [email protected] > [mailto:[email protected]] On Behalf Of Nate Duehr > Sent: Tuesday, October 20, 2009 11:48 PM > To: [email protected] > Subject: Re: [Repeater-Builder] kendecom repeaters on 220 > > > > > > > On Oct 18, 2009, at 11:28 AM, Jed Barton wrote: > > > Hey guys, > > > > I'm working with a group and have given them several suggestions for > > repeaters on 220 including hipro, ge, moto, etc. > > One thing i don't know much about is the kendecom, and thought i > > would ask > > since they want to know. > > As far as relyability, good, bad? > > Reliability: Looking inside ours, at the quality of the components, I > would have given it only a few years before it fried. Surprisingly > it's been up for way over 10 years now. Maybe 20? Originally > installed when novices were given 220 MHz voice priveleges, hard > linked to 2m, so they could talk to the higher license classes. > > We keep "meaning to" replace it with a converted MASTR II, but it > hasn't forced us to make it a priority, if you catch my drift. > > Complaints match Kevin and other's comments: > > Squelch action, crappy. Seriously crappy. Way too much hysteresis > means you have to crank it way up to get any kind of decent squelch > action. > > RX is relatively deaf, but workable with a pre-amp. (220 is so darn > QUIET, it's hard NOT to hear signals... so "it works", but it could > work a LOT better.) > > Like almost everyone else, the club's main techs at the time, ripped > out/bypassed the internal controller. It was so long ago, I wasn't > even a Ham back then (prior to 1991 for sure!) and did a custom > interface to an S-Com controller. Sounds like they'll do it for you > at the factory these days. > > The really annoying one for us has been this: > > TX frequency stability is very poor. We have to put it back on TX > frequency on a regular basis (annually at least). The potentiometer > quality used for this adjustment is abysmal and gets worse to fiddle > with every year it gets older. Another one of those dilemmas... "mess > with it and put in a multi-turn pot, or just replace the whole thing > with a GE?"... > > (We just had our first "neighbor" pair on 220 utilized in the area, > and the owner is someone I know. He noted that we're off frequency in > his direction (this time) a little bit, and I promised him I'd go > tweak the thing again at first opportunity.) > > Oh... almost forgot about this one: > > Getting the cover off and working on the thing in a rack-mount > environment is a complete PITA. Put a rack shelf under it for when > you need to get at the guts. Have a place to put all the little > screws (or ditch half of them and never put them back) and make your > cabling long enough to turn the thing upside down on the shelf if you > have to troubleshoot the underside of any of the circuit boards. > > Ours took a lightning hit -- again, more than ten years ago -- which > toasted some of the metering circuitry, making the pretty little > meters on the front, somewhat useless in some modes of the switches. > Unbelievable that it survived, it has ball lightning marks at the > screw holes in the front in the blue paint, to this day. Oh, by the > way... lesson learned... scrape the pretty blue paint off around those > holes and get down to bare metal before shooting your rack screws into > it. Waste of pretty blue paint, since you want your rack rails > properly grounded to the repeater's case anyway. > > Four or five years ago, we found a dried out capacitor in the audio > chain that caused it to sound horrible. > > (Perhaps that's why Bob can always tell them, and other people rave > about their audio... again, low quality components...) It was a chore > to follow the audio chain through the thing (upside down) with a scope > to find the stage that was dead. Once found, and replaced, it popped > back to the usual good quality audio we were used to hearing out of it.) > > My plan has always just been to replace it... everything else in the > network other than the 1.2 GHz analog machine, is GE MASTR II's... no > reason not to continue the "standardization process" eventually, when > other more pressing issues are completed. Working on the MASTR II's > is just easier. > > It'd make a good "basement/backyard" repeater. On a mountain, in > tight working quarters in a rack, it's a pain, and the build quality > just isn't what we like to use. > > The MASTR II shelves are MADE to drop them open and work on them on- > site... etc. Why fight with it? It ever dies, it's not getting > repaired to go back to the hill. > > That's probably enough. I won't "bash" them completely, but I > wouldn't put another into service. Especially not at their "very > proud of this blue box" NEW pricing. Ouch. > > -- > Nate Duehr, WY0X > n...@... <mailto:nate%40natetech.com> > > http://facebook.com/denverpilot > http://twitter.com/denverpilot >
