BCT-8 Garbled Audio in Trunking mode--only

[kskarma]

I have (3)- BCT-8's that I have owned for 5-6 years and after about that length of time, they all have developed an audio problem when trunking...and ONLY when trunking. The best way I can describe it is like a radio that is tuned just a bit 'off-frequency'...or when you are hearing a Single Sideband ham on a regular shortwave radio. You can kind of make out most of the words, but they are not as clear as they have been...

SO...for the first two of my BCT-8's, I sent them off to Bearcat service and for the standard fee ($50 as I recall), they repaired them and they have worked fine ever since...this was within the last year or so for these two that I sent them.

This question is for the true tekkies on here? Is getting these back to correct operation on Trunking just a matter of a bit of alignment, or do you think some component was actually replaced? The 'Repair Tag' does not shed much light on this...I think it just said..."Repaired and Tested"... IF...it is just a matter of tweaking an adjustment in the scanner, I am competent to do that...but I would need to know WHICH coil or pot to adjust...assuming that the component is accessible..

If no one has any actual expertise about this, I will just send this BCT-8 (Number 3..!) off to Bearcat and cough up the $50 for the service. Being a bit cheap...and having some 'experimental urge', I would not mind trying to fix it myself...and pocket the $$$$$...

 

[DaveIN]

Without a service manual you can just guess, but it does sound like a filter problem. It would be odd however to just have the problem on the trunked receive only, unless a different set of filters are used for the trunked mode. Do you load the radios using external software? Is this a Motorola or EDACS trunked system type? If EDACS I'd make sure the frequencies are entered correctly. If Motorola, I'd use the Control Channel only setting fro TrunkTracking.

Does this happen when using the Highway Patrol or Police search bank as in, does it sound garbled on a Motorola trunked system when the radio tracks a Motorola system in the search bank mode?

 

[kskarma]

I don't think any of this applies...but...I appreciate your post.

DaveIN...Thanks for your response. I'll try to address the questions you raise. First of all, the basics.... The 3 BCT-8's I have are all set up identically. Two of them are used in the house in separate locations, the other one is in my car. All of them have a very basic Motorola trunking system of 15 freqs.... and 4 of those freqs rotate on a daily basis as the control channel. ALL of them work perfectly for about 4-5 years...good audio, NO problems...then...over a period of a few months, I notice a gradual deterioration in the audio quality...until finally I am really unable to understand anything. IF I turn off the "trunking", the radios work fine...but of course, are NOT in trunking mode, but rather just receiving 800M freqs...I have to manually lock out the control channel...and change it each day, but the audio is OK when operating that way.

I don't quite understand the direction of your last paragraph...the 15 freq. system here is used by a LOT of services, Police, S.O., HiPatrol, and many others. I typically have 50 TG's in the banks..and, as I said....these all work fine and have for many years...so I don't think any of the Programming issues you touch on could be a problem.

 

[DaveIN]

In the search bank Police and Highway Patrol it has the ability to stop on a Motorola control channel and start tracking (if the control channel only mode is active). Does the radio still sound off frequency when using this mode?

 

[kskarma]

DaveIN.... I fail to see what you are getting at with your question... IF you read my posts, you should see that the BCT-8's ALL have worked fine for a long time, and then two of them...and now the third, have developed a problem in the Trunking audio... Uniden / Bearcat has fixed two of them...and now those two work as intended. I fail to see what could be learned by whether or not the Search works...as that would NOT fix my problem. IF I had been doing anything wrong in the setup or programming, I think that Bearcat would have told me so...and...I don't think they would have worked correctly for such a long time...

And, yes....it does fail the same way in Search...but...I could care less about that...as I want it to work right in Scan....which is how I use it... Thanks for your efforts...

 

[w2csx]

Just a guess, but maybe your area has switched to apco p 25???

 

[kskarma]

Close...but NO cigar....!!!!

Let me ask you, have you actually READ my postings?? This has happened before...to two other BCT-8's... And...currently those two are working perfectly fine after having been serviced by Bearcat. And...while some of the radio users here DO use APCO...(i.e. digital)...those are not the freqs. that I am having this problem with...(with just this ONE BCT-8)..the others work fine...as does my BR-330T.

My many years of servicing main frame computers for a BIG company (guess which one!) would suggest to me that if you have 4 units of any kind...and three of them work just fine...and one does not...that the problem just MIGHT be with that one unit....!!!

I am NOT a novice in this...have had many scanners over the years (about 35 years and as many scanners!), I currently have about a dozen running...a few in Trunking...a few that do not Trunk.

This just reminds me a bit of the problem that used to happen to the Bearcat 250 scanners....after a few years of service..when they would develop "Bearcat Disease"...a problem with the CPU chip I think... They would get to the point where they were unable to store freqs...or scan..etc. It was only repairable by Uniden and I think I had or knew of 4- 250s with this problem.

 

[w2csx]

kskarma., i didn't mean to offend you ... sorry

 

[sector4666]

Trouble with trunking

A friend has the same touble, not with the BCT 8 , but with the 2 top of the line scanners
made by both top competing companies. He thought it was his scanner , a Fixed Base unit, So he purchased another from the competing company, another fixed digital apco 25 base unit . He is a ham and works as a radio tech for a large corporation and is extremely knowledgable with radio equipment
He can only use the radios, ( each) with the tiny stubby duck antenna to receive...or get what one referred to as sounding slightly off frequency. the problem he insists is he is unfortunately located in a
" Simulcast OVERLAP SIGNAL ZONE " of which there are many . In other words, receiving signals from two or more towers simultaneously , micro seconds apart...is what causes this weird phenomena...
This could possibly be your problem , and many others for that matter with the 800 , in our case 700 & 800 systems now coming on the air . Something to look into .....

 

[homer545]

I have the same problem with my BCT8

kskarma: Just wondering if you found an answer to your problem? My BCT8 is doing exactly the same thing. It would be nice to be able to fix it without shipping it out to Uniden.

Thanks

 

[N8IAA]

Additional thought---have you tried attentuation? Is it on a Simulcast/multisite system? Less signal is better for those.
Larry

 

[kskarma]

OK...good points from both of you..but since two of my BCT-8 have NO problems...nor does my BR-330T, I have to conclude that it is the scanner that is faulty...esp. in view of the fact that within the last 2 years, 2 other BCT-8's have developed the exact same problem. With each of those, I tried a lot of fixes, workarounds, etc...altering the stored freqs a few KhZ, attenuation, temperature of their environment..on and on. When those were giving me trouble, the APCO system had not yet been activated. The one that is having crappy audio is currently in my van...and no matter where I drive, it does the same thing...this would be over some 30-50 miles radius...so signal strength is not a problem...no intermod, etc.

Finally, a visit to the "Home Base" in TX...fixed the problem...and both of those have been working fine ever since...

And...N8IAA..fyi ...yes...as far as I know this trunking system uses 2 main towers, one on either side of town. Closest one is about a mile away...other one is probably...4 miles distant. Have never had any indications of front end overload with these...or any other of my scanners at my location. I currently have 5 other non-trunking..but 800Mz, scanners operating..in "Manual CC lock out" mode. No problems with any of those either..2 are RS, 3 are Bearcats..small ones...BCT-7, BC-700 & BC-350C. All have the identical freq. layout / sequence of the 15 freqs. in the trunking group.

 

[homer545]

I found the solution to this problem.

Take the bottom cover off the radio. On the bottom circuit board of the radio directly under the speaker magnet there is a varible coil. Take a small flathead screwdriver and turn the coil about 2 millimeters clockwise. Boom......you will have clear audio in trunking mode once again.

I have done this and it corrected the problem with my BCT8. I read on a couple of other forums that the magnet in the speaker is causing the inductance in the coil to go out of wack.

Let me know if this works for you.

 

[kskarma]

I sure will give that a try....soon..

homer545.. That sure sounds like something I will try shortly. And...even if it does not work, I will be no worse off than I am now....! When I do stuff like this, I make a tiny mark at the original position so that I can re-set the pot, etc. back to the unchanged location if needed.

Thanks again...and I will update this after I give it a shot... If this works, I will send you a "virtual $50 bill"......<GRINS>!!!!

 

[w2csx]

I found the solution to this problem.

Take the bottom cover off the radio. On the bottom circuit board of the radio directly under the speaker magnet there is a varible coil. Take a small flathead screwdriver and turn the coil about 2 millimeters clockwise. Boom......you will have clear audio in trunking mode once again.

I have done this and it corrected the problem with my BCT8. I read on a couple of other forums that the magnet in the speaker is causing the inductance in the coil to go out of wack.

Let me know if this works for you.

WOW is that weird or what!

 

[kskarma]

The BCT-8 FIX is in.....or....&quot;ON&quot;....WHEEE!!!

It looks like all it takes to remedy this condition is the "fix" that is outlined in homer545's posting. I just did that to my BCT-8...and BINGO....the audio is now clear and it stops on Trunked Transmissions as it did before..and just as my other two BCT-8's do.

Step-by-Step Directions....

Remove power from the scanner. Remove the 4 phillips head screws that are found on the sides of the bottom cover. Carefully pull off the bottom cover...it might be tight and there are wires to the speaker that you need to be aware of...so take it easy..

Locate a small tuneable coil that is close to the center of the circuit board. It is silver in color and about 1/4" square. Examine the top and you will see the 'slug' with a small screwdriver slot in it. For 'insurance' purposes, mark the exact location of the slot...just in case you need to reposition it if you screw up. (Ask me how I know to do this....!!)

At this point you might want to position the scanner so that you can re-attach the power cord and be able to put the bottom cover back to the point where it might be close to its original position. You might find that when you do this, the scanner will work as when new....or...you might not. This step is just a bit of 'experimenting' and might give you an idea as to how far out of alignment it is.

Now...for the actual 'surgery'...with a small screwdriver, turn the slug in the coil 'Clockwise' a very small amount ! In my case, it was almost the smallest amount that I could move it...and still be able to say that I had indeed adjusted it. Now...attach the power cord again...and give it a try. You should hear a big improvement...this might depend on how far out of adjustment it was. You may want to give that slug another slight tweak...or not. The 2mm movement that was mentioned in the preceeding post is a good guide...I don't think I went that far....but the change was immediate.

My Wild A** Guess about this is that some of the components (a capacitor most likely) in the tuned circuit has changed value over the years...with time, heat, cold, etc. and has allowed that tuned circuit to become 'detuned'.... Since I am guessing (again!)...that your BCT-8 was working fine for a long time and then over a period of a few months, it got more and more flaky...that would mean that only a tiny bit of tweaking is going to be all that is needed to bring it back to 100%..

Before reattaching the bottom cover, let it warm up for a half hour...listen to the audio...bask in your new success, give a big THANKS to Homer545...then remove power, replace the bottom...and SCAN AWAY!!

I am sending a stack of Virtual $50 bills to Homer545 for this tip....and if it works for you, please do the same...!!!

 

[homer545]

Glad to hear that it worked for you also.......i will by 50 virtual beers with the virtual 50 bucks....

 

[saleen49]

This is an awesome thread. I was having the same problem with my BCT8 and not just in Trunk mode. I found it necessary to turn the tuning pot screw 45 degrees to get clear audio again. I can now get quality Trunked reception thanks to this thread.

Thank You!

 

[kskarma]

Saleen49...Your timing with this posting is on the money. I just put this "fix" on another of my BCT-8's a few days ago...I did not have to rotate the pot as much as you did, but it put things right again. Being able to make this adjustment and to NOT have to send it to Bearcat for their $50 service has saved me the cost of a few years subscriptions to Radio Reference....

And another "Thanks to Homer545" for the initial hint about this...!

 

[Jethro32]

Thanks Homer545, Ive been going crazy trying to get my BCT8 to work since the rebanding in my area. Your post did the trick.
Thanks!