BC125AT - Very poor reception - cause?

[blacktop]

Hi all,
I recently purchased a second hand BC125AT (I already had another 125AT that I really like). The person I got it from I believe to be a genuine person and thought the scanner worked fine. In fact, he told me he took it to one or two auto races and that was the extent of its usage. I believe that, as the unit was in pristine condition on the outside, not a mark to be found ANYwhere, even on the screen. When I got it home I first tried to tune the local weather broadcast. It sounded like it might be 30-40 miles away the level was so low (and white noise mixed in with the audio). No bars were showing on the received signal indicators. The transmitter is essentially clear line of sight, and only being 10 miles away.

Does anyone have any thoughts on how or what in the unit may have gone bad (other than the obvious 'antenna/antenna connector got hit and there is a solder break' scenario).

I exchanged the OEM antenna with a VHF mag-mount 5/8 just to validate that it was not a bad antenna, but there was no change. I tried an extendable stick as well, same deal. Again, I don't know if the radio took a hit (but he assures me it didn't) and if it didn't, what might cause such a drastic change in receive sensitivity.

I'm not new to this stuff, I have about 30 scanners or so and I know you pretty much need your habds on the radio and the right test gear to answer my question. I guess I'm really looking to find out if there is a known systemic issue with these radios.

thanks in advance

 

[jonwienke]

Most likely problem is a static discharge or too much RF hit the antenna, and the protection diodes or the first stage amplifier transistor got smoked. That won't leave any marks on the case, but will bork reception.

 

[riccom]

That or the solder joint came loose from the BnC to the board

 

[jonwienke]

The only other possibility would be something wedged in the BNC connector, preventing the antenna from connecting properly. Did you check that?

 

[pb_lonny]

I can't say I have ever heard of this, have you compared them side by side?

 

[pinballwiz86]

I guess I'm really looking to find out if there is a known systemic issue with these radios.

No, there is no known reception issue with the 125AT. It is a great little radio. I think you will like it too once it works again. Too bad yours needs a repair. Send it in to Uniden.

 

[nanZor]

Note that VERY early units had an issue where the radio seemed deaf on certain freqs, and cpu noise made it seem deaf or very noisy on some VHF freqs. An early firmware update that lowered the cpu speed seemed to cure that.

This was only with handheld antennas - it could not be heard with an external antenna using a transmission line, sometimes with heavy common-mode choking applied, so essentially the radio was receiving itself / rfi / common mode noise etc.

Not sure if this is your case, but just a caution to be wary of when buying used.

 

[blacktop]

Hi jonwienke,
Thanks so much for that. At least that gives me an good starting point. Some other great advice there too. I did check the connection...it looks great. When I disconnect the 5/8 VHF mag mount, everything is gone. Connect it up again, and the local weather is 'just there'. {sorry, wrote this reply yesterday, but forgot to push 'post reply}

pb_lonny: Yes, I tried a side-by-side between my original 125AT and this one. No comparison. The original works great, but the second 125AT is just not pulling anything in.

nanZor: Firmware in both is 1.04.02 Great suggestion, but I'm thinking that is not likely the issue.

riccom: Yes, I had that happen on another hand held once...I'll pull it apart and have a look. Would be nice if that was it. The fact that it 'kind of' starts to work when I hook an antenna on that feeds it a decent signal, it starts to receive very faintly, every time. Wiggling or gently tapping never yeilds a reception change or any associated 'crackling' that might indicate a break.

pinballwiz86: I think sending to Uniden may be the way to go, but it is sad that it costs nearly as much to repair as it does to simply buy a new one....

thanks everyone

 

[pb_lonny]

Sorry it sounds like it is stuffed... I have a new UBC126AT coming, I hope it works well...

 

[wtp]

did you swap antennas between the two radios ?

 

[blacktop]

did you swap antennas between the two radios ?

Yes, I tried 3 different antenna in each BC125AT...same result every time...original 125AT works great....2nd 125AT nearly deaf.

pb_lonny (Paul): It's unlikely that it is a manufacturing defect....you'll probably be good to go once you get it in your hands.

 

[wtp]

thanks for the answer, i just want to touch every base.

 

[blacktop]

thanks for the answer, i just want to touch every base.

Appreciate all of the help. Going to send in for repair... thanks.

 

[majoco]

Has the BNC antenna socket had a 'wrong plug' pushed in to it and spread all the little fingers so they don't touch the pin of the antenna? Have you swapped antennas across from the good to the bad and vice versa? and as other have said - is the BNC connector still joined to the PC board and is it slightly loose? Does it have an "ATT" (attenuator) button - usually it would show something on the display but I haven't got a 125! It could still be a static discharge into an external antenna that has zapped either the input protection diodes or the RF amplifier FET transistor.