At 01:48 PM 12/16/03 +0000, you wrote: >Hi all, > >I'm just starting to get into ham radio repeaters and have a couple >of beginner type questions. My club is looking to purchase a used >MSR-2000 VHF repeater. I've done some background research already >and it sounds like a good unit. What I want to know: is it a >synthesized or crystalled repeater, and if the latter what are >typical costs for having crystals made? > >Thanks! > >Jeff
It's a crystal-based radio, but the crystals are installed inside factory packaged transistorized crystal oscillators called "channel elements". Any decent vendor will have included a pair with your MSR (Probably already installed inside the RX and exciter housings). If you can get a spare set for a reasonable price, it might be worth it. I haven't priced a set of MSR elements recently - I'd call International Crystal (http://www.icmfg.com) at 800-725-1426 and ask them. If your MSR is going to be located at a radio site that will have wide temperature swings you'll want to have the crystals installed in the elements an thermal compensated by the crystal manufacturer. Just tell them what frequency you want the radio on, then send them the old elements and a check. It goes without saying that before you do so, make sure that the repeater is operating within specs on the original channels. Look at the web page at http://www.repeater-builder.com/rbtip/m2icoms.html - while it's oriented towards the GE equivalent to a Moto channel element the last three paragraphs regarding thermal compensation hold true for Moto as well. Moto elements are self-contained - there is no Moto equivalent to an EC element. Moto elements are either 0.005% (commonly called a silver element due to the raw aluminum color) or 0002% (usually in a gold anodized case). I personally use International Crystal even though they are the most expensive. Considering what I am spending on the entire repeater, the extra $ is down in the noise level. And a properly compensated channel element won't drift, and you only have to pay once. I learned the hard way about mountaintop repeater temperature compensation with my first UHF repeater - the first cold snap was simultaneous with the first snowfall and the repeater TX zoomed to about 8 khz high and the RX was worse and in the opposite direction. Withe the RX that far off frequency the touchtone decoder wouldn't decode. I ended up using a friend's synthesized UHF base to shut the system off - my crystal-controlled base wouldn't tune down far enough. We warped the base station master oscillator far enough to get the system to respond. Once it was shut off I sent a spare set of elements to International, and when they came back I swapped them into the repeater. I set them on frequency then, and touched them up 6 months later. They've been perfect since. The MSR can be likened to a Mitrek mobile married to a Micor base. There is some relevant info at http://www.repeater-builder.com/rbtip/mitrek-index.html The element part numbers for a MSR are: 0.005% (silver element) 136-174 & 406-512: RX KXN1086 TX KXN1088 0.002% (gold element) 136-174 & 406-512: RX KXN1112 TX KXN1095 30-50mhz elements are RX: KXN1085, TX KXN1087 Good luck and let me know what you end up doing. Mike WA6ILQ Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
