MSF-5000 Info Needed

KI4M · Post by **KI4M** » Mon May 01, 2006 8:16 pm

I have come across a used MSF-5000 UHF base station.. I am thinking about a possible purchase but the model id # is missing from the case. It is a 450MHz split base. It is a 100 W unit and is ex-military unit. The problem is it appears to have 2 separate exciter/receiver units. They are combined into a (I am assuming coaxial relay) listed as option BR. Has anyone ever had any experience with this or seen this before.. This is a digital base with the LED display on the controls.. I have searched here and the internet for hours to no avail.. Someone has to have seen these before.. Looking to convert to 440 ham use but do not want to pick this unit up if it has some special firmware etc that might not allow it to work on ham FM use... Thanks ahead of time.. Shane KI4M

kb0nly · Post by **kb0nly** » Tue May 02, 2006 8:19 am

http://www.repeater-builder.com/motorol ... index.html

Check out the photo tour page of the UHF, there is model number decoding info, etc.

kcbooboo · Post by **kcbooboo** » Tue May 02, 2006 8:25 am

If you can get inside the station, you might find some stickers on various assemblies that would give you the model number.

The stations have the ability to support two RF trays with one control tray, so that could be what you've got. If so, the second RF tray could be removed, leaving you with something that's more like what you're used to seeing. Of course, if the station IS a Special Product (with an SP number), then all bets are off. Stock firmware might put it back to normal too. It depends on what's in there right now.

The bandwidth of the receiver isn't very wide, and if they needed to cover frequencies that were spaced more than 6 MHz (or so) apart, the second RF tray would be the way to do it. The coaxial relay might be there to switch the outputs to the power amplifier, although I'm not aware of any mechanism in the station to do that. Maybe they added something to accomplish that task.

Bob M.

KI4M · Post by **KI4M** » Tue May 02, 2006 9:00 am

kb0nly · Post by **kb0nly** » Tue May 02, 2006 9:32 am

I couldn't get any of the pictures to load here for some reason.

kcbooboo · Post by **kcbooboo** » Tue May 02, 2006 10:15 am

I had no trouble with the pics.

The station has a secure module and TTRC in it and is digital-capable, so it's a CXB.

There's a wildcard module, or something hand-wired, in the expansion tray on top of the control tray. This probably has something to do with switching between the two RF trays.

The long tubular thingy along the back under the power amp is the low-pass filter. The left side comes from the PA output; the right side goes to a T/R relay or its own RF output jack.

If you flip down the PA, you should see a sticker on it somewhere with a TPN number, or something like that. With that number, we can give you the power rating, although it's probably 75 or 110 watts. My best guess for the model number would be C64CXB7106B or C74CXB7106B, with possibly a SPxx after it, due to the two RF trays, relays, and expansion box.

I've never seen those two relays on a station. You'd have to trace the wires and see where they go. Each RF tray has a receiver input SMA jack on the right side which would go to a T/R relay or its own RF input jack. The exciter output is another coax that comes from underneath the rear and usually loops along the left side of the RF tray. Normally this would go to the PA input.

It would help to see a photo of the side junction panel.

With luck, it's just a standard station inside, with the addition of the circuitry in the expansion tray to switch between the two RF trays. You'll have to follow the coax wiring. Also try to see what controls the two relays; if they're powered from the same two wires I'd bet they go to the expansion tray.

Bernie might be able to shed some light on this if he can view the photos.

Bob M.

KI4M · Post by **KI4M** » Tue May 02, 2006 10:23 am

kb0nly wrote:I couldn't get any of the pictures to load here for some reason.

Try them again i found a small problem with the link that might have caused some problems.. let me know...

KI4M · Post by **KI4M** » Tue May 02, 2006 10:26 am

kcbooboo wrote:
If you flip down the PA, you should see a sticker on it somewhere with a TPN number, or something like that. With that number, we can give you the power rating, although it's probably 75 or 110 watts. My best guess for the model number would be C64CXB7106B or C74CXB7106B, with possibly a SPxx after it, due to the two RF trays, relays, and expansion box.

I've never seen those two relays on a station. You'd have to trace the wires and see where they go. Each RF tray has a receiver input SMA jack on the right side which would go to a T/R relay or its own RF input jack. The exciter output is another coax that comes from underneath the rear and usually loops along the left side of the RF tray. Normally this would go to the PA input.

It would help to see a photo of the side junction panel.

With luck, it's just a standard station inside, with the addition of the circuitry in the expansion tray to switch between the two RF trays. You'll have to follow the coax wiring. Also try to see what controls the two relays; if they're powered from the same two wires I'd bet they go to the expansion tray.

Bernie might be able to shed some light on this if he can view the photos.

Bob M.

Bob;
I am getting these pics from the guy who has this unit.. I will try to get him to take some better detailed pics for me tonight... i will try to get all the above photos from him.. I am wanting to turn this into a 440 Ham rptr.. just don't want to buy a pig in a poke... lots of money to throw away if it will now fit the bill...

kb0nly · Post by **kb0nly** » Tue May 02, 2006 11:08 am

Well i'll try again later, for some reason i still can't view the pictures, either get a 404 error on the link or a server busy message.

I'll check them later tonight when i get back.

kb0nly · Post by **kb0nly** » Tue May 02, 2006 11:51 am

Ok, now the pictures are working. Must only allow so many connections at a time.

kb0nly · Post by **kb0nly** » Tue May 02, 2006 11:54 am

I saw one like that on ebay a while back, though i can't really offer any info on it.

Bob is the MSF guru..

kcbooboo · Post by **kcbooboo** » Tue May 02, 2006 12:31 pm

Depending on what you're paying for it, it could be worth taking the gamble. Other than the two extra relays, the expansion chassis, and the extra RF tray, it should still be a standard station inside. Of course, if it's 403-435MHz, then it won't be easily pulled up to 440-450 MHz. That's one thing you'd want to verify. I don't think there's a 475-512 MHz range for these, so it's either the low or mid range; you want mid range.

Usually the RF tray will have a white sticker or two on it giving the full model number, serial number, factory order number, and possibly date of manufacture. There could even be one on the inside of the cabinet. It's odd not to have one on the outside on the junction panel.

Judging from the photos, it's probably in a 42 inch cabinet also, as that would have enough room for the 2nd RF tray and blank panel under the main RF tray.

I could tell a lot more if I had my hands on it or could connect a computer to it and run RSS !

Bob M.

kcbooboo · Post by **kcbooboo** » Tue May 02, 2006 1:05 pm

Looking back at the photo of the relays, I'm offering this conclusion.

The lower relay with N connectors is probably an ordinary T/R relay. The base station needs one. The center connector seems to go to the RF jack on the junction panel, while the left connector goes directly to the upper relay's "S" jack. I'd bet the upper relay switches the antenna to one or the other RF tray, that lower tray probably contains just a receiver.

That would all make a lot of sense. I just don't know what they use to select the 2nd receiver. I suppose the logic in the expansion tray could be looking at the MUXBus signals and checking the active receiver channel, and switching the upper relay (the one with "Option BR" on it) when they want to use that other receiver. The transmitter is capable of a wider frequency range than the receivers are.

You want to make sure it's a 435-475 MHz split and not the 403-435 MHz range. The part number on the PA would help; the last digit is usually 1 for range 1 (403-435) and 2 for range 2 (435-475).

Bob M.

bernie · Post by **bernie** » Tue May 02, 2006 1:58 pm

My two bits worth:

IF this is ex US military it is most certainly in the R-1 split, which means you would have a case and power supply, as well as lots of hardware.

I would suppose that it could be up-banded to 440, but I would not want the job.

In the chance it came from a police department, then you might have a winner.

Check the labels to see what split it is in.

This appears to be a secure base with a second receiver. The box connected to the antenna relay is a 2-way power splitter. It may have an amplifier.

I would just un plug the Wild Card and forget about it unless you have a specific application for it.

The firmware is likely "stock". Not really a concern.

KI4M · Post by **KI4M** » Tue May 02, 2006 3:41 pm

kcbooboo wrote: You want to make sure it's a 435-475 MHz split and not the 403-435 MHz range. The part numb4er on the PA would help; the last digit is usually 1 for range 1 (403-435) and 2 for range 2 (435-475).

Bob M.

Bob I just found out that the PA is a TLE 2521A so.... That would make it a low split.. Dang that stinks.. Guess my hunt is still on for a MSF-5000 UHF mid split...

I would like to thank everyone on here for their help in this adventure... At least I learned a bunch while investigating what this was.. Guess I might have to break down and hunt around here locally... If anyone knows of a nice base or rptr UHF MSF-5000 around for a reasonable price let me know... I would be in the market for a digital unit with at least 75W out... like a C64 or the like.. would consider anything higher power... Thanks and I will be around to offer some help if I can..

kcbooboo · Post by **kcbooboo** » Tue May 02, 2006 3:50 pm

Yup, 75w 403-435 MHz power amp. That would make the station a C64CXB7106B-SPnn or something close to that.

Good luck on your search. Check local radio shops first, as shipping will kill you, unless you can find one dirt cheap but in good condition across the country.

It was an interesting exercise, however. Glad you didn't get stuck.

Bob M.

d119 · Post by **d119** » Thu May 04, 2006 6:53 pm

Why the heartaches about bringing R1 stations up to the ham band?

I did three Canadian (C44RUB) MSF's that were Range-1, and they tuned up in 440 just fine... Granted the receiver sensitivity wasn't spectacular, but thats nothing a properly tuned preamp can't fix...

Whats the guy want for the thing? I'll take it...

kcbooboo · Post by **kcbooboo** » Fri May 05, 2006 3:20 am

Maybe it "worked" at 440, but would it also work at 449.950 RX, 444.940 TX, or 444.975RX, 449.975 TX? If the station has the internal filter / duplexer, adding a preamp to it is not feasible due to the TEE cable and the fact that the front end is part of the duplexer.

Contact the original poster via PM for more info.

Bob M.

kcbooboo · Post by **kcbooboo** » Fri May 12, 2006 12:25 pm

I think it's up for sale on eBay right now.

Bob M.

d119 · Post by **d119** » Sat May 13, 2006 1:55 am

FWIW, the 403-435 unit I purchased does not use internal duplex, and tuned up on RX at 442.900 with .4uV RX Sens, and 100W out on 447.900.