Re: [Repeater-Builder] Re: Retuning a UHF Motorola Micor without a deviation meter or signal generator ?
Thanks for the help, Josh! I've saved this email to reference when the time comes to do the work. From what I've seen, there are at least five different documents out on the web concerning the retuning of Micor's into the ham bands, but they all start with assumptions of a well-stocked test bench and some fairly good knowledge of the "geography" of the Micor systems. I'm hoping to compile everything that I can find together into a document that will act as more of a real project plan, from "parts and equipment needed" through buttoning everything down and putting it in operation. When/If I get it done, I'll be sure to put it in the files for this group. Thanks again! Brian, WW9A Columbus, IN > >From: Josh >To: Repeater-Builder@yahoogroups.com >Sent: Sun, May 30, 2010 12:03:28 AM >Subject: [Repeater-Builder] Re: Retuning a UHF Motorola Micor without a >deviation meter or signal generator ? > > > >Brian, >Here's what your project would look like. > >First, you'll need crystals. Those can be ordered. > >Second you'll need access to a 'test set' of sorts for the micor. There are >several types, this'll set you back $20 to $100 (depending what test set you >get). This is necessary to 'tune' the RX and TX on the unit to work with your >new crystals. > >Third, You've got filters to tune. The easiest way to do this is with a >spectrum analyzer and tracking generator. I just bought one for $1100 - there >are other, less accurate ways to do this, but I chose the 'buy the right tool >for the job' route. You really want to see whats going on. This same tool will >be required (or use other processes) to tune a duplexer so you can use a >common antenna for TX and RX. > >You'll be interfacing an external repeater controller (not difficult, although >I'm fighting a COS issue right now on my micor project) to give you a time out >timer, CW or voice ID'er, and the DTMF control you'll want (disabling the >repeater if it goes berzerk). I'm using the NHRC-2 , under $100 if you do it >as a kit. > >Micors are REALLY easy to work on and a lot of fun - I'm getting close to the >end of my project on one here, and I've learned a ton. > >If you don't have access to the tools, and dont have friends that do, there >are folks on the groups (this and others) that might be willing to 'tune >stuff' for you, so you can do all but a few parts yourself. > >Good luck with your project! > >Josh >--- In Repeater-Builder@yahoogroups.com, Brian Smith wrote: >> >> I will apologize in advance, as I am an extreme newby in the world of >> repeater building / operation. >> � >> We've been donated a UHF Motorola Micor system.� The system has >> documentation that shows that it once ran at 78W out in commercial service. >> � >> Being an amateur radio operator without a commercial or well-stocked test >> bench, I do not have ready access to a deviation meter or signal generator. >> Is it possible to retune these things down to the amateur radio 440 band >> without these two pieces of test equipment? >> How likely is it that I will run into significant performance issues without >> these pieces of equipment? >> � >> Thanks! >> Brian, WW9A >> > > >
Re: [Repeater-Builder] Retuning a UHF Motorola Micor without a deviation meter or signal generator ?
The power output is from the a sticker on the front of the transmitter with a hand-written "78" in the watts blank. The repeater is currently in the 455 range and we have been coordinated the 442.225T/447.225T pair. As guessed, I am located in Columbus, Indiana (about 40 miles south of Indy). Thanks for the help! Brian, WW9A > >From: Mike Morris >To: Repeater-Builder@yahoogroups.com >Sent: Sun, May 30, 2010 12:22:26 AM >Subject: Re: [Repeater-Builder] Retuning a UHF Motorola Micor without a >deviation meter or signal generator ? > > >At 08:31 PM 05/29/10, you wrote: > >>I will apologize in advance, as I am an extreme newby in the world >>of repeater building / operation. > >No apology needed. We've all had to start somewhere. > >>We've been donated a UHF Motorola Micor system. The system has >>documentation that shows that it once ran at 78W out in commercial service. > >Is that on the "Power Set" sticker, or do you actually >have a station logbook? (very rare). > >>Being an amateur radio operator without a commercial or well-stocked >>test bench, I do not have ready access to a deviation meter or >>signal generator. > >Nobody does when they get started. But both can be "faked". > >>Is it possible to retune these things down to the amateur radio 440 >>band without these two pieces of test equipment? > >Yes, but it is more difficult without them. > >Where is the station now (i.e. frequency) ? > >Where are you going? (i.e. frequency) ? >Do you have a coordination there? > >A peak deviation meter can be faked with a >DC coupled oscilloscope and a discriminator >based receiver, You offset the transmitter + >and - 5khz and adjust the gain so that the display >shifts + and - 5 lines on the scope face. Then >you run enough audio into the transmitter to >saturate the audio stages (i.e. force it into limiting) >and set for 4.8 KHz. Set this way nothing is going >to go beyond that point. Then you adjust the level >from the repeater controller for a 1:1 repeat gain. >There's more to it than that but that will get you >started. > >A signal generator can be faked with a >programmable scanner (you use the local >oscillator / multiplier as an uncalibrated >radiating source). There was a comment >thread on that topic not long ago, you >might want to check the list archives. > >>How likely is it that I will run into significant performance issues >>without these pieces of equipment? > >You might want to say where you are. This mailing list >has almost 5,000 members worldwide, mostly in the USA, >and we might have someone local to you that would >be willing to "Elmer". > >And retuning the station only has to be done once. When >I was getting started I would take the receiver and transmitter >chassis over to a friends 2-way shop, we'd tune them up, >and I'd take them back home and do the rest of the work >there. > >>Thanks! >> >>Brian, WW9A > >Your license comes back to Columbus, Indiana which >is south of Indianapolis. Is that where you are located? > >Mike WA6ILQ > > >
[Repeater-Builder] Retuning a UHF Motorola Micor without a deviation meter or signal generator ?
I will apologize in advance, as I am an extreme newby in the world of repeater building / operation. We've been donated a UHF Motorola Micor system. The system has documentation that shows that it once ran at 78W out in commercial service. Being an amateur radio operator without a commercial or well-stocked test bench, I do not have ready access to a deviation meter or signal generator. Is it possible to retune these things down to the amateur radio 440 band without these two pieces of test equipment? How likely is it that I will run into significant performance issues without these pieces of equipment? Thanks! Brian, WW9A
