Hi, I'm trying to tune an analog UHF MSF5000, I have an rf voltmeter but don't have a probe tip that will fit into the holes on the filters, can I get away with just adding a wire to the end of the probe or do I need the tuning tool kit. If I inject the receive frequency into the receiver input I get a reading on the meter that responds to adjusting the filter screws. I tuned the receiver and transmitter filters this way, seems to work ok but I have some desense.
Thanks,
Ken
MSF5000 Tuning
Moderator: Queue Moderator
The holes in the filter cavities are for injecting a signal and taking a meter reading on of the meter pins. If you don’t have the book as I guess. I can post part of the tuning info on my server.
Special equipment is nice but not needed. The injection probe is a piece of small coax that barley enters the cavity without upsetting the tuning of it.
The meter is actually a 50 uA movement with a switch to select the different metering points.
If you have desense, you likely have other problems though. It is configured as a repeater? Do you have a duplexer?
Nand.
Special equipment is nice but not needed. The injection probe is a piece of small coax that barley enters the cavity without upsetting the tuning of it.
The meter is actually a 50 uA movement with a switch to select the different metering points.
If you have desense, you likely have other problems though. It is configured as a repeater? Do you have a duplexer?
Nand.
MSF5000 Tuning
Nand,
Thanks for the reply. The radio is an internally duplexed C64CLB7106AT. I do have the manual and MSF test meter. The manual idicates that you inject your receive freq into J11 (filter input) and using an rf voltmeter and probe inserted into filters tune for peak/dips. I tuned the injection/image filters using the test set ua meter. The desense I have is on weak signals that will pump the repeater on/off. Just thought that by not using the correct probe I may not have tuned filters correctly.
Thanks for your help,
Ken
Thanks for the reply. The radio is an internally duplexed C64CLB7106AT. I do have the manual and MSF test meter. The manual idicates that you inject your receive freq into J11 (filter input) and using an rf voltmeter and probe inserted into filters tune for peak/dips. I tuned the injection/image filters using the test set ua meter. The desense I have is on weak signals that will pump the repeater on/off. Just thought that by not using the correct probe I may not have tuned filters correctly.
Thanks for your help,
Ken
"Just thought that by not using the correct probe I may not have tuned filters correctly. "
Hello Ken,
I'm by no means an MSF expert, I did one that way and my end result was the same as yours. I got a hold of a tuning kit and realigned the station and it made a night and day difference.
Doug
Hello Ken,
I'm by no means an MSF expert, I did one that way and my end result was the same as yours. I got a hold of a tuning kit and realigned the station and it made a night and day difference.
Doug
May the Schwarz be with you.
My error. I assumed you were asking about the RX frontend tuning where the holes in the cavities are used for inserting a signal.
I never had an internal duplexer and never tuned one.
Getting the correct cable as Doug suggest is likely the way to go. It prevents the probe from detuning of the cavity if it is inserted to deep.
Nand.
I never had an internal duplexer and never tuned one.
Getting the correct cable as Doug suggest is likely the way to go. It prevents the probe from detuning of the cavity if it is inserted to deep.
Nand.
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MSS-Dave
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Ken...
With the internal duplexed MSF, you have to follow the tuning instructions exactly or it will desense itself to death. I tried the "manual SINADDER" read: ears and it don't work. I have a C74CXB7106 in service, at rated power(internal duplexer) I have less than 1 dB of desense. Jacking the amp up to 135 watts out yielded the same. I have tuning info if Nand doesn't have it to post, let us know.
Dave
With the internal duplexed MSF, you have to follow the tuning instructions exactly or it will desense itself to death. I tried the "manual SINADDER" read: ears and it don't work. I have a C74CXB7106 in service, at rated power(internal duplexer) I have less than 1 dB of desense. Jacking the amp up to 135 watts out yielded the same. I have tuning info if Nand doesn't have it to post, let us know.
Dave
MSF5000 Tuning
Thanks guy's for the reply's,
The desense I have is very minimual, I just like to have everything perfect. It's a lot easier to tune things at home, repeater site is a pain. Can somebody describe the tuning cable, can I make one, or order one from Motorola if it's available. I'm using a Motorola 1340A rf voltmeter with the probe that came with it, just doesn't work with holes in filters. This is a amateur repeater, now running a micor that just won't die, been running for many years without much attention and still sounds great, guess I'll have to shoot it. Don't know why we got this MSF5000, seemed like a good idea at the time.
The desense I have is very minimual, I just like to have everything perfect. It's a lot easier to tune things at home, repeater site is a pain. Can somebody describe the tuning cable, can I make one, or order one from Motorola if it's available. I'm using a Motorola 1340A rf voltmeter with the probe that came with it, just doesn't work with holes in filters. This is a amateur repeater, now running a micor that just won't die, been running for many years without much attention and still sounds great, guess I'll have to shoot it. Don't know why we got this MSF5000, seemed like a good idea at the time.
My two bits worth:
You will not likely get this radio to spec with out following the alignment instructions EXACTLY.
One of the necessary steps is that the filter being aligned is properly terminated with a 50Z load.
I usuially use a second analyzer in place of the RF voltmeter.
I also suspect that an RF probe would do as well.
I have some extra alignment cables, and I would give you one for the cost of postage.
You will not likely get this radio to spec with out following the alignment instructions EXACTLY.
One of the necessary steps is that the filter being aligned is properly terminated with a 50Z load.
I usuially use a second analyzer in place of the RF voltmeter.
I also suspect that an RF probe would do as well.
I have some extra alignment cables, and I would give you one for the cost of postage.
Aloha, Bernie