BCD436HP/BCD536HP: UHF Reception Issues due to Noise from Battery Compartment

[kc5igh]

If you want LSM, get a used one of these: :Unication Co., Ltd.

I've taken a hard look at the Unication pagers, especially since their prices recently came down by nearly $300.

The system I'm monitoring has partially converted to Phase II radio traffic, and it's my understanding that the Unication pagers don't yet have Phase II capabilities. That's supposed to change when some new software becomes available, so I'll keep checking on that possibility.

I'm guessing that Uniden and Whistler are hard at work on LSM-capable scanners, but we won't know anything about that until they're ready to go to market. I, for one, am ready to pay Unication prices for a Uniden or Whistler scanner that reliably decodes LSM traffic!

Thanks.

 

[rbrtklamp2]

I picked up a new 436HP last week and right off the bat I could tell that it was receiving better than my last one that had the copper tape. The latest 436HP Main Board - V: 1.09.02 S:7C3D VD5857 SN# 376Z780019xx

Where did you purchase the radio from?

Sent from my SM-N910V using Tapatalk

 

[Starman918]

How can I tell if my BCD436 needs the "tin foil treatment". Is there certain serial numbers involved. Thanks

 

[dcisive]

The easiest answer to that in my opinion would be to best take a several layered foils square about the exact size of the inside of the cover. Tune to a weak frequency in the say mid 400mhz ranges. Place it on hold. Then place the foil square firmly OVER the inside of the cover and foam (don't remove the foam) and strongly put the cover in place. If you note the signal strength improving (most likely dramatically) then you'll want the foil in place all the time. To confirm with the foil in place scan and find a frequency in the mid 400mhz range that is half way decent in strength. Then remove the foil and place the back back on. You'll probably notice the frequency all but if not completely disappear. If so then you have your answer. I'm betting the foil WILL dramatically improve the signal quality. In the end I've found frequencies in as low as the 100mhz ranges are ALSO improved as well. Give it a try.

 

[troymail]

I determined it would (and did) help my situation by both:

- my Whistler picked up the UHF systems that the 436 would not at the same location

- attaching a (cheap) external antenna to the 436 and moving the antenna away from the radio (the UHF frequencies came to life).

After applying the foil, the radio started receiving (UHF DMR systems) without an external antenna.

 

[Starman918]

Thank you for the replies. I will try it.

 

[KevinC]

Most of you didn't see this as it was on the DFWScan Yahoo Group, but this is the first time I've seen Paul publicly admit the issue...

"One version of the main board had a noise issue that caused poor VHF/UHF performance. One way to see if this is the case is to just put a remote antenna on the scanner. If VHF/UHF improves, then that is likely the issue. There is a big thread at RadioReference where this has been discussed (Missing C1 capacitor might be a keyword for finding it...or poor VHF performance).

We'll fix it at no cost if that is the issue. If that happens not to be the issue, there would be a charge (i.e. if bandpass filter is blown)."

 

[troymail]

Most of you didn't see this as it was on the DFWScan Yahoo Group, but this is the first time I've seen Paul publicly admit the issue...

"One version of the main board had a noise issue that caused poor VHF/UHF performance. One way to see if this is the case is to just put a remote antenna on the scanner. If VHF/UHF improves, then that is likely the issue. There is a big thread at RadioReference where this has been discussed (Missing C1 capacitor might be a keyword for finding it...or poor VHF performance).

We'll fix it at no cost if that is the issue. If that happens not to be the issue, there would be a charge (i.e. if bandpass filter is blown)."

Interesting ... for lots of reasons - not the least of which is the "stealth" admission. But since there is no "repair program" for this, I guess it's up to me to pay to send it in (and hope they don't decide it is something else and they want more of my money..).

 

[k3fs]

Since there has been some admission, and this is a true defect. Can this get a sticky. it would certainly help people who wonder what the problem is. Granted, it is a long thread, and mostly deals with our efforts to root out the cause, and remedies. But, it is still relevant to the radios and could be helpful. There are many radios out there that still have this issue. This is also the thread he is referring people to as well.

If only we could get an update on the advertised features that are still missing.

 

[k3fs]

Interesting ... for lots of reasons - not the least of which is the "stealth" admission. But since there is no "repair program" for this, I guess it's up to me to pay to send it in (and hope they don't decide it is something else and they want more or my money..).

I agree. Not the way to handle it. But, this is more of an admission to the defect than I ever expected to see. They messed up on their original repair program, and are only willing to look into it if someone pays to have it looked at further. It would also be a night mare for them to correct this the right way.

When there is a problem, admit it as soon as possible.
Customers are not stupid. Ignoring or denying a legitimate problem is not the way to handle it.

 

[Eugene]

Would have been nice to make that admission here since we now have 48 pages on the subject. Mine is 1 year old (and no way to know how long it sat at Amazon) so I know I don't have the "C1" fix. Since it was stated on a Yahoo forum I may want to wait to see if what was stated (about fixing it "at no cost if that is the issue") will truly happen. I don't like being the guinea pig and don't like suggesting others be as well, but if others do go this route, perhaps posting how it went may help others make the decision of foil vs fix. Thanks.

Eugene KG4AVE

 

[jonwienke]

If it's a 2016 serial, ("Z6" in serial number) then you've got about a 60% chance C1 is installed. If it's 2015 or earlier, then it doesn't have C1. I've installed C1 in numerous 436 scanners, and it's not that risky of a thing to DIY if you have skills with soldering and basic hand tools.

 

[Eugene]

Which I unfortunately do not. Not with fine work like circuit boards. I will have to check....I may be lucky

Eugene KG4AVe

 

[fourthhorseman]

Is there a shot of the PCB showing either the pad either populated, or unpopulated..

Ive got a 436 coming home today from repair, I noted the C1 on the repair form....But didnt see it on the work order...
Would like to visually verify, while its getting the GPS treatment..

 

[jonwienke]

Checking for C1, and installing it if it is missing, is standard when I install a GPS.

 

[fourthhorseman]

Checking for C1, and installing it if it is missing, is standard when I install a GPS.

have a PCB Shot?

 

[Nasby]

have a PCB Shot?

I do know that somewhere in this thread there are some nice photos of the C1 in place and one where the C1 is missing. Hope that helps.

 

[royldean]

has a serial number cutoff been determined for the C1 capacitor? I've got a 5800 serial number.

 

[jonwienke]

Sometime in 2016, but I can't be more specific.

 

[jonwienke]

have a PCB Shot?

It's next to the battery terminal on the right when looking at the back of the display board.