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 wa6...@gmail.com 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
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
