MSF ID Problem???

[Big Towers]

Here is a new one on me. Analog UHF MSF5000. Been on for about a year, working fine. Just recently I noticed that it no longer is sending out its CW ID on use and at 15 minute intervals. Was doing so just fine. Repeater working fine otherwise, and is a single user repeater.

Based on how the CW ID is generated, gotta wonder why. Anybody have this happen before?

[Al]

I've had the same thing happen on a digital 800 Mhz MSF5000. Of course, Bernie is the expert on MSFs here, and he pointed me in the right direction. Seems that the controller is verrrry polite, and if the RX squelch is not set to close when the rx carrier goes away, the transmitter will never ID. If you have a test set, it's easy to check the rx squelch level and reset so that it closes when it should. That fixed my problem.

[Big Towers]

Thanks Al,

Didn't think of that, but very possible. The repeater is hardly ever used and so I have not noticed the squelch tail which may be an indication. I have a test set at the site, and am gussing that it probably is the Squelch setting a little to low. Just 2 hours away, so maybe later.

Thanks,

Tom

[airman1952]

I agree with Al.

I had the same exact thing happen to me a year or so back.
Also a analog MSF. (not that it matters). Plugged the DMP
in and noticed the Rx squelch was flickering. The county had
done some changes on their system where my repeater is and
it raised the noise floor a little. It never affected the repeater operation
because it was looking for PL, but it would no longer ID. Tightened the
squelch up a little and fixed the problem.

Maybe you have had a noise increase at your site all of a sudden.

How is the weather their? I grew up in Hamilton. Also lived in Missoula,
and Helena for a while. Moved away in 77.

Good luck,

Gary

[bernie]

My two bits worth:
Al has it right.

You would not notice the squelch being open in a PL station.
If this was a Carrier Squelch station the "squelch" noise would be heard during repeater Drop Out Delay period.

In the CLB version this is the Squelch control on the front panel.
On the CXB there are two squelch settings, the front panel, which becomes active when the test switch is set in the UP position "Access disable"
When ACC dis is normal the internal R1 EEPOT sets the squelch.

I must admit that I did not set the squelch on the MSF I tuned last week.
It did not ID, and it required a trip to re set the squelch.

[kcbooboo]

Thinking back about two years when I got my first MSF5000, I didn't have a digital metering panel (why Motorola even bothered to make one without the LEDs is a mystery to me) and I figured "I'm running PL so I'll just leave the squelch fully open to get maximum sensitivity." The built-in CW ID would always do strange things, like fire once and then never again until I keyed it up again, or ID every 8 minutes whether there was a carrier present or not.

Once I got a DMP, I saw the flickering RX UNSQUELCHED and RPT UNSQUELCHED LEDs, and it all became much clearer. Also, when working on these in a nice warm basement, I observed a lot more things about the station that just weren't visible out in a cold garage. For example, the receiver qualifier settings in RSS allow for tone squelch alone, or tone squelch plus carrier squelch. When set for just tone, you will get a longer squelch tail with loss of carrier since the tone decoder has some built-in hysteresis. Adding the carrier squelch qualifier lets the noise squelch circuit mute the receiver a lot faster when the input carrier goes away, so you get a much shorter squelch tail. This setting doesn't affect how the receiver unsquelches.

There are actually three squelch settings on a CXB station: the front panel squelch knob, the RX SQUELCH EEPOT, and an RPT SQUELCH EEPOT. You really need the DMP to set the two EEPOTs since there's no other indication that they're actually opened or closed. Considering all the LEDs that are on the front of a CXB's controller for the transmitter and PA, It would have been very nice to include at least one LED for the receiver.

Bob M.

[bernie]

My two bits worth:
As Airman1952 observed the site noise effects squelch setting. Site noise can change, as well as component aging in the radio can cause changes in squelch threshold.
Do not assume that all is well because you have PL.
The only way to tell if you have problems is to do "Effective Sensativity"
tests.
(Squelch=make quiet)
This is how I set the squelch controls using a regular Motorola test set with MSF cables or the standard metering panel.

Connect your signal generator to the repeater receiver with an iso-tee.
System design determines squelch, repeater key levels.
It is also possible to set R1PL DET with the DMP, or RSS, set the repeater key as you would squelch.
Voting systems generally require the squelch to be set at 20DBq point.
This is because analog voting comparators do not work well on noisy signals.
Stand alone repeaters are usuially set at 15DBq or what ever.
The reason for the repeater squelch level is to reduce keying on un usable signals, default settings allow the repeater to remain keyed on PL alone.

CLB:
Connect the test set.
Set generator to desired quieting point.
Always monitor station audio with test set, or hand set.
Enable PL generator, adjust repeater squelch starting at minimum until the repeater keys.
Turn the generator off, reduce level to minimum, turn back on, gradually increase signal until repeater keys to verify keying level.

Set test switch to PL MON.
Set squelch control while listening to the test set speaker, or an AC volt meter on audio test point to specified level, or slightly above opening point

Return PL monitor switch to normal.

CXB:
Set up as above.
There are two ways to set the EEPOTS. I use the RSS, along with a custom programming cable that allows measuring audio, as well as mike audio for setting MAX Deviation.
One can also use the test switches to set the EEPOTS. Consult manual for procedure.
Set Repeater squelch as above.

Receiver Squelch:
Set test switch to PL MON, set R1 Squelch via RSS to desired level, monitoring local speaker as above.
The front panel control squelch is only active in the ACC DIS position, has no effect on station operation with test switches in center (normal) position.
I have found that 5 clicks beyond critical squelch works well on digital MSF.

In Motorola trunking systems the green indicator on the RIB for the channel under test iluminates when the receiver is un squelched.
If the squelch is set too "loose" you may have RIB failure on the channel.

Motorola design philosophy is to have the receiver under transmitter control via signalling, (PL, DPL, trunking) eliminating the carrier squelch.

It is possible to modify Motorola equipment for "And Squelch", defeating Motorola's superior weak signal performance.

In response to customers complaining about noise bursts from their "cheaper"radios, I have made these mods in the past only to find that the system performance degraded due to squelch chopping on weak signals.

[Big Towers]

Hey guys,

I haven't gone to the site but was at another site yesterday where I can get a strong signal from the repeater in question. Although it is PL, I can key it up with a non reverse burst radio and listen to the "squelch tail" with a portable. Sure enough, nice long, shouldn't be there squelch burst on unkeying. Reverse burst radio, nice and quiet. So, no doubt, the RX squelch has opened up and is preventing the ID.

Will get there someday, we have the Digital Test sets at each site so no big deal to go up and tighten it up.

As we are the only thing on the air, I suspect it just "happened". Nothing new to raise a noise floor, so a quick twist and all should be well. Thanks for the help, will remember next time when one of the other 5 start acting odd.

Weather in Montana has been great, a little too great. Very little snow in the Mountains, 55 degree days for the next 10, short sleave weather for the last several weeks. Glad I don't live in really cold places like Chicago, Boston, New York!!!