BC92XLT Issue ?

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Ganuke

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Hello,

I have been a long-time reader and sometimes poster here. Currently there is an issue with a scanner that I am wondering if anyone can assist with ...... or even confirm it being an issue with this scanner. It is a Uniden BC92XLT scanner which is actually owned by a cousin of mine. He has owned this scanner for about 2 years now so I'm sure by now the warranty on it has expired. To the best of my knowledge my cousin has not dropped or otherwise put this scanner through abuse. In fact because of the problem he has had with it..... he has rarely used it. As I said..... I posted here before in regard to my own scanner ( A Radio Shack Pro 92 ) and have received very good help and information from members here. So really...... while a post-warranty scanner could not be replaced by the manufacturer ..... still would like to know what the real problem with this scanner could be and if it is a known issue with this scanner.

Ok...... that problem with this Uniden BC92XLT is that it constantly stops on low band frequencies that have been input into the scanner. These would be frequencies such as in the 47.XXX range and 33.XXX range. My cousin had told me that the scanner would just ' get stuck ' on various frequencies. It is when I brought it home to tinker with the frequencies and see if I could figure out what the issue may be that I came to realize the problem ( at least having had it for a few days now ) is with just the low band range.

The scanner will stop on any and all low band range frequencies and literally be stuck there. When I first took the scanner home I filled it with known active frequencies that I have in my Radio Shack Pro 92 scanner ..... figuring those would mostly all work well in his scanner from his house which is just 3 miles away. After inputting those...... as my cousin had said..... it started getting stuck on frequencies all of which after having had it for a few days are in the low band range as I said above. In fact...... I just had to lock out another one as I have that scanner on while I write this.

I have tried turning the squelch slowly and completely clockwise ...... and it still remains stuck on any low band frequency that it stops on with the ' snowy ' noise. I also put a Diamond RH77CA antenna onto my cousin's BC92XLT in place of the stock antenna it came with thinking that it might just be the result of a crummy stock antenna that is causing the thing to get stuck on all the low band frequencies. Doing that had no better result as the scanner still kept getting stuck on the same low band frequencies that I had input into the scanner.

The ' good ' thing is that the area in which my cousin and I live has recently been moving their scanner frequencies for such things as Police, EMS, and Fire to a higher range above the low band area. Prior to this most of the police, EMS, and Fire frequencies were in the low band range. That is why my cousin had gotten so frustrated with it continually getting stuck on most of the frequencies that were needed to pick up most activity in our area. Now with this recent move of the Police, EMS, and Fire frequencies up the band range ....... I've input the newer higher range frequencies into his scanner from what I had in mine ( which I got in large part from here at Radio Reference. :) )

Hopefully all frequencies that can be found in our area move out of the low band range which would seemingly make this scanner completely useful for my cousin finally. Also my cousin didn't just completely ignore the issue from when it first started. He was twice at the retailer that had sold him the scanner and told them what was happening with it getting stuck on frequencies. He did this about 2 or 3 times..... each time the place would keep the scanner for a few days...... call him back and said they had corrected the problem. My cousin would then go to pick it back up only to find out a short time later the BC92XLT was still getting stuck on the same frequencies ( which now I know are all in the low band range. ) It was going to be a 4th time my cousin went back to the retailer who sold him the scanner to try and once again get th problem with the scanner fixed but before doing so he had called them to explain that the problem with it was still going on. Whoever took the call at the retailer told him that they remember him and the issue with his scanner and that they had fixed it and there was nothing wrong with the scanner...... this after my cousin brought up about having the thing just replaced as it was then still under warranty. That phone call concluded with the person from this retailer again saying they had fixed the problem and there was nothing wrong with the scanner ....... and that he must be inputting the frequencies wrong so it would not be replaced even though at that time it still had warranty coverage.

I actually find all the detailing about this now..... like I said above I'm sure much too late for anything to be done about it. Had I known fully about this back when his scanner was still under warranty I'd of called the retailer myself ...... and if he wasn't given a replacement ..... would have emailed a long ( longer than this post :D ) and not so happy letter about what was going on with this scanner and the retailer who sold it to my cousin..... to Uniden myself. My cousin is one who doesn't like to raise too much of a fuss on stuff. I on the other hand am one to raise a big fuss if I feel a consumer is getting messed over.

Anyway..... long post I know...... and basically wondering if anyone knows of a possible solution to this problem with my cousin's BC92XLT ? At the least ...... does anyone know of this being an issue with this particular scanner ?


Ganuke
 

CStarr59

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Location
Schuylkill County PA.
I've had my bc92xlt for about 2 years and it has always worked perfectly. About 2 months ago it started just as yours, getting stuck on low band frequencies. I assumed it was electrical interference but it has gotten worse. Even outside it does it now away from all electrical distractions. So basically it sits unused in my scanner drawer. Recently I purchased a psr-100 and it has made me a happy scanner again. I really don't think the bc92xlt is worth fixing at this point. It gave me many happy hours of service, but now its time to move on.
 

Ganuke

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Feb 2, 2005
Messages
25
Location
Pennsylvania ( West-Central )
I've had my bc92xlt for about 2 years and it has always worked perfectly. About 2 months ago it started just as yours, getting stuck on low band frequencies. I assumed it was electrical interference but it has gotten worse. Even outside it does it now away from all electrical distractions. So basically it sits unused in my scanner drawer. Recently I purchased a psr-100 and it has made me a happy scanner again. I really don't think the bc92xlt is worth fixing at this point. It gave me many happy hours of service, but now its time to move on.
Yep..... this particular scanner I have of my cousins I just wondered if this was a common happening for the thing..... like a known issue. From lack of response in this thread ...... maybe it isn't and he ended up getting one of the few BC92XLT scanners that refuse to bring in low band frequencies without getting stuck on them. And with wondering if this was a known issue for this scanner..... basically wondered if there was any quick / easy fix for it. I agree that it would not be worth the effort to open the scanner up to try and diagnose the problem myself...... and not sure I'd even know where to start for that matter. And the warranty on this scanner has come and gone. I would have liked to have known the lack of assistance my cousin was getting by the people at the retailer where he had this scanner purchased while the thing was still under warranty. I'd of raised a nice fuss over it and not have taken any ' well you are just programming the thing wrong ' response.

But too late for that as well. And not even sure at this point in time if emailing Uniden would do any good as well with the scanner being out of warranty...... even if it was just to bring up the issue with the scanner while expecting not much in response / reaction to it. So having had this scanner of my cousin's for a bit over a week now...... basically the ' fix ' I went about with it as I described in the last post was basically just to input the known active frequencies I have in my own Rdio Shack Pro 92 into his scanner. Well..... at least the frequencies that I have which are active ...... and are above any XX.XXX low band range. After having done that and spent a few days and nights with it on to test it out making sure it didn't still get stuck on any of the higher band frequencies...... results seem good..... no sticking. And it worked out nice as I said in the last post...... since many of the fire / EMS / Police frequencies in the area we live have moved from low band to a higher band frequency just in the past few months.

With that said...... still doesn't make me happy that his scanner has this issue in the first place. And if anyone else out there knows of this being an issue with this particular scanner ..... do chime in. Or for that matter if anyone knows of some fix to it ..... chime in as well. I plan on giving my cousin his scanner back tomorrow ....... set up with the active non-low band frequencies I input which should get him using it again for the first time in a long time at least. But would be nice if there is some fix to this that can be done to get it bringing in the low band frequencies without getting stuck as well.

Ganuke
 

wbswetnam

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Same low band problem with 92XLT

Mine has the same problem - it seems to lock up on lowband frequencies. If I set the squelch to the middle position it isn't aas bad but then of course, you miss weaker stations. Not a major issue in most parts of the country anymore, since lowband is now (mostly) only used by state patrol in a handful of states such as CA, MO and WV. Still, if you are on vacation and you want to use the "Service Scan" for police or fire, it locks up on low band frequencies - it doesn't allow you to select/unselect individual public service bands for service scanning like the RS Pro-96 will allow you to do.

For $120 dollars it's not a bad little scanner aside from this fault. But if you are in one of those places that still uses low band, it would suck, I agree.
 

WA1ATA

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Have you verified that the problem is actually in the scanner rather than simply being lots of noise on the VHF lowband?

If you remove the antenna, does it still get stuck/lockup/unsquelch on the lowband freqs? Is the squelch setting that locks the scanner signficantly different between low band and hi band when you have removed the antenna?

Do you have other receivers/scanners that you can use to compare the amount of background noise on the lowband vs. highband and UHF?

I have noticed that on both my Uniden 95XLT (similar to the 92) and also on my Radio Shack/GRE scanner that the lowband has much more noise and will lockup the scanners at lower squelch settings than for VHF Hi or UHF or 800.
 

SCPD

QRT
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This is a common "feature / fault" with the 72XLT and 92XLT. Here in Australia we have the UBC73XLT and UBC93XLT which both do much the same thing. Myself and others have seen this happen and can not work out why :(

Paul
 

nanZor

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Ok, this is happening on both my 92xlt and 72xlt - that I love for what they are. Not happening on any of my other rigs.

Maybe we can find something in common, and perhaps develop a work-around.

My testing is going to try two things - to see if it is a timing issue, or if it is a large frequency jump that is causing it while scanning.

I took a look at my 92 and 72, and noticed that my low-band freqs are preceeded by a UHF frequency.

So what I'm trying now is a timing issue - I'm just temporarily locking out the preceeding frequency in memory and will scan for a few hours to see if the squelch opens on my low-band freq again. Maybe this will give just an extra bit of timing to the scanner as it detects a lockout, and then moves on towards the low-band freq.

If that proves unsuccessful, I'll try programming in a VHF frequency just before the low-band freq, and see if a smaller jump in frequency prevents the open squelch deal.

It'll take awhile, so I'll let you know if anything good comes out of this...
 

WA1ATA

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Fairhaven MA / San Jose CA / Kihei HI
I've noticed that the squelch seems to have a lot of hysteresis. In other words, once unsquelched the signal level has to be significantly lower before it will start scanning again. Generally that's a good thing, but it does tend to make the 72/92/95XLT lock up on VHF low signals. It seems like the base noise level is higher on VHF Lo than other bands. My scanning locations have always had a higher external noise floor in low freqs from the various bits and pieces of electronics gear in my house, so I had always assumed it was that rather than a problem with the scanner.

In some radios, there are adjustment pots to set the relative squelch threshold for various bands. Per the schematic over on the Yahoo BC92XLT group there doesn't seem to be one.
http://f1.grp.yahoofs.com/v1/AH5vTm...BC72XLT SCHEMATIC ( 2006 with closecall ).pdf

You might be able to reduce the squelch hysteresis by tweaking RT2, but I haven't tried that.
 
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nanZor

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Spent all day on this! Having both a 95xlt and 72xlt along with a 346 and 396 for backup helps narrow the problem. :)

No amount of fiddling with programming like putting vhf-low into it's own bank, preceding a vhf-low with a lockout etc does anything to trick some sort of timing issue. Scratch that out.

Basically the testing revealed that there is a random pll/vco unlock that blows the squelch open on vhf-low. It can take up to 2 minutes to recover depending on the frequency.

With both the 95 and 72, I factory-reset them. Then I programmed each identically with about 10 vhf-low frequencies. Both are using the same antenna (800mhz rs duck). Nearby is a 396 with a bandscope, and the 346 is using the close-call.

Then the squelch blows on one unit, it will be just fine on the other. An hour later, the problem changes to the other scanner. Nothing seen nor heard on the 346/396.

During these minute-long blowing-squelch situations, even a power-cycle of the scanner returns to the same open squelch! WOW.

I suspected voltage irregularities, so I tested both again with Uniden-supplied ac adapter, and also with fresh alkalines - it didn't make a difference. The rechargeables are Sanyo Eneloops, babied in a Maha, and selected to be the best mates by selecting those closest in capacity to each other. No difference.

Thinking that it might be my local FM station pulling it off frequency somehow, I attached a PAR FM broadcast filter inline. Nope - an hour later, blowing squelch. And also doesn't explain why one unit is affected, while the other isn't - only to change places with the problem 20 minutes later.

Even when you don't have the blowing squelch issue, when I opened up the squelch and listened to each programmed channel, you could hear the vco/pll grinding away in the background trying to get it's act together. You could hear the change in pitch as it went along. Change to another channel, wait a few minutes, and it comes along slowly. So even if it doesn't blow squelch, there is a general sensitivity problem as something *internal* sweeps through the band.

Now here is where it gets really weird:

If you remove the antenna, the problem goes away. AHA - must be external - but the 346/396 don't detect a thing wrong. Without the other radios for support, it would be easy to assume that it is an external source causing the issue - I did at first.

So, put the antenna back, and this time while the squelch has been blown open, touch the base of the bnc connector. The scanner squelches! When the scanner finally settles down, touching the base of the connector doesn't make any difference. Even open the squelch when the scanner seems normal, and touching the base makes no difference.

Both units were opened and the bnc connector is just fine. Very beefy actually. All screws were tightened just a tad more on both sides of the boards, although they were definitely not loose. Nope, no change.

The best I can determine at this time is that the "call is coming from inside the house". :)

That is, yes, it takes an antenna attached to have the problem. A paperclip works. The pll/vco randomly unlocks, squelch blows, and then takes awhile to lock up again. It is almost as if something unlocks inside, and a feedback loop is created.

Man, this is a shame. While I don't concentrate on vhf-low, this random unsquelching takes my love for these inexpensive but generally well-performing units down a notch. The first indication if you only have one of these, is to look for an outside problem, when it really seems to be a random internal issue. :(
 
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nanZor

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Even the 346 / 396 are not immune to low-band internal noise

This same phenomenon is also present with 346 / 396 units, although to a much lesser degree!

We have a master oscillator or clock putting out spurs in the vhf-low band. These spurs contantly change by moving up in frequency.

You need an antenna to allow the radio to listen to the spurs. In the 346/396 case, there seems to be better shielding/filtering, so the spurs are less in number, but they are there. With the extra sensitivity of the 346/396, you may not even need the antenna!

You can program a conventional system as a test on a 346/396, pepper it with vhf-low freqs, use FM to hear it better, and eventually you will have the same problem, only it will take much more time as the spurs move more slowly. Yet when it happens, squelch will blow, and it takes at least a squelch of "10" or more to stop it - sometimes max squelch won't work if it is a strong one.

Heh, 34.700 just blew squelch on my 396 right now. Yet an Icom R20 and RS Pro-106 show no outside interference issues. They are MUCH cleaner than the Uniden's on VHF low.

For fun, you can even track them as they qsy up the band by using a direct frequency search, places a hold on it, and then following it with the tune-knob.

Man, this was driving me crazy. It's just internal birdies, spurs, whatever you want to call it, which sweeps up the band. Tolerable on the 346/396, but absolutely unusable on a 72/95xlt.
 

SCPD

QRT
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Excellent work in finding the problem, glad it is not just us over this side of the world that has this problem.

Paul
 
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