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

[bg_nashville]

I recently bought a Diamond SRH789 to use with my 436hp. I was extremely pleased with the results. I also tried the antenna on my 396xt. With the antenna extended to 12 inches on both radios, the reception in the 460MHz range was about the same on both radios.

I didn't think adding copper foil tape to the battery door on the 436hp would improve reception even more, but it did. Amazingly, I am sitting here listening to a Kentucky State Police P25 repeater that I have never heard before that is 80 miles north of Nashville.

I didn't notice a difference until the third layer of tape. I stopped at the fifth.

 

[bearcat]

I recently bought a Diamond SRH789 to use with my 436hp. I was extremely pleased with the results. I also tried the antenna on my 396xt. With the antenna extended to 12 inches on both radios, the reception in the 460MHz range was about the same on both radios.

I didn't think adding copper foil tape to the battery door on the 436hp would improve reception even more, but it did. Amazingly, I am sitting here listening to a Kentucky State Police P25 repeater that I have never heard before that is 80 miles north of Nashville.

I didn't notice a difference until the third layer of tape. I stopped at the fifth.

Great! I been trying to emphasis that it is not what you ARE hearing. It is what you are NOT hearing.

 

[jeffm77]

Have we gotten the results back from the member that was going to use a SA to do testing?

 

[N1SQB]

Did mine today! Interesting in that it does improve my 450-460s a little bit. Worth the $6 I spent on the 6 foot roll.

 

[KevinC]

Did mine today! Interesting in that it does improve my 450-460s a little bit. Worth the $6 I spent on the 6 foot roll.

It would work a lot better on top of the foam so it touches the batteries.

 

[bearcat]

Did mine today! Interesting in that it does improve my 450-460s a little bit. Worth the $6 I spent on the 6 foot roll.

I cannot tell how many layers you have on there. Somewhere around 6 layers should yield the best results with copper and as KevinC stated go over the foam. The improvement will be significant.

 

[N1SQB]

Um Ok! Back to the ol drawing board! LOL I was going by the pics on the first few pages. Time to add a few more layers besides the two already on there. :roll:

Manny

 

[ur20v]

I cannot tell how many layers you have on there. Somewhere around 6 layers should yield the best results with copper and as KevinC stated go over the foam. The improvement will be significant.

I would think the number of layers used would be dependent upon the thickness of the copper tape used, seeing as some tapes are 1 mil while others are 4 mil.

 

[bearcat]

I would think the number of layers used would be dependent upon the thickness of the copper tape used, seeing as some tapes are 1 mil while others are 4 mil.

Excellent point! We have found (at least with copper) that too much will have an adverse effect. When I got to 8 layers the noise got worse. I think we had 1 mil.

 

[KC0KBC]

Great! I been trying to emphasis that it is not what you ARE hearing. It is what you are NOT hearing.

Duly noted, but let me say - I just did mine tonight, four full layers plus a narrower reversed layer against the foam (so I can undo all this), all on top of the foam. It's too soon to know if I'm hearing anything "new" but I'm hearing all the usual stations with better signal strength and much better clarity. One of my systems is about 30 miles away and has always had some noise on it, now it's just as clear as systems 5 miles away.

 

[bearcat]

Duly noted, but let me say - I just did mine tonight, four full layers plus a narrower reversed layer against the foam (so I can undo all this), all on top of the foam. It's too soon to know if I'm hearing anything "new" but I'm hearing all the usual stations with better signal strength and much better clarity. One of my systems is about 30 miles away and has always had some noise on it, now it's just as clear as systems 5 miles away.

Agreed. Many of my noisy UHF analog stations are now crystal clear and the ones I could not hear at all are now great also. Many DMR stations that would not decode at all, now come in perfectly clear. My current testing is a battery case sprayed with nickel RF/EMI paint 10 coats and an aluminum shielding tape just covering the foam. It really works well. I should say that I am splitting hairs. The door I covered with aluminum shielding tape also works very well.

 

[RFI-EMI-GUY]

I havent read all the thread posts, however I am wondering if there is any effort being made to bond the door to the circuit board ground ? It would be more effective in my opinion.

 

[Comp-100]

I havent read all the thread posts, however I am wondering if there is any effort being made to bond the door to the circuit board ground ? It would be more effective in my opinion.

It's been suggested in the thread to try to use the negative battery terminal as a ground. I seem to recall someone tried a quick test and it was not helpful and maybe detrimental; which is quite strange.

While we know that you can sniff some signal in the area, it is not known that the signal there is infact the one causing the issue since there are no circuit measurements yet that give any indication of the source of the issue. It's still in theory possible that it is not an internal signal but an external signal, but the nature of the reports seems to indicate some fairly wideband noise. Not to say that could not be generated by something like DTV signals.

 

[bearcat]

It's been suggested in the thread to try to use the negative battery terminal as a ground. I seem to recall someone tried a quick test and it was not helpful and maybe detrimental; which is quite strange.

While we know that you can sniff some signal in the area, it is not known that the signal there is infact the one causing the issue since there are no circuit measurements yet that give any indication of the source of the issue. It's still in theory possible that it is not an internal signal but an external signal, but the nature of the reports seems to indicate some fairly wideband noise. Not to say that could not be generated by something like DTV signals.

The noise is broadband probably over 250mhz wide. I highly doubt it is from an external source, it is being generated by the something in the radio. If it were external then the SA would also see that same noise which it does not until you probe the middle battery positive side.

 

[Comp-100]

The noise is broadband probably over 250mhz wide. I highly doubt it is from an external source, it is being generated by the something in the radio. If it were external then the SA would also see that same noise which it does not until you probe the middle battery positive side.

I agree basically, but reports are too varied yet to say for sure so i was just saying there are few absolutes at this point. The fact that external antenna seems to be unaffected also points to an internal source, but i don't know if there are enough data points on that yet. The wideband nature of the noise seems to create a very different type of behaviour. It's like the noise is actually entering at an intermediate stage based on signal levels vs audio and digital decode reports, if this is true an external antenna should not overcome the issue in all cases.

 

[scannersnstuff]

absolute horse doodie that you have to do this with a $500.00 scanner ! .

 

[bearcat]

absolute horse doodie that you have to do this with a $500.00 scanner ! .

You are correct. If I say something was missed in design, quality, or whatever. I will get attacked by those who think this problem does not and never has existed. Quite frankly I love everything about the radio, except the sub par performance on UHF. It has been discussed for two years. Most who make the claim that it is sub par are attacked as if it we are making it up. Now there is proof. There is some sort of noise that is overloading the receiver on UHF. I can tune to a know active freq and remove my shielded battery door and the signal will totally disappear, slide it back on and a perfectly full quieting signal appears. Hence without the shielded door you will never hear a peep.

As far as Uniden goes, I have no idea what they may or may not do. Did they already know about the noise but it is within their specs? Did this hit them by surprise?

I know that I am just happy to have this unit now working at a level of performance that I expected when I got it. To those who do not have the issue hats off to them. They do not know what they are missing.

If you want to get best performance get some shielding tape and your noise problem will go away. Read the various posts on the best shielding methods. I have found aluminum shielding tape, not foil from the kitchen works best for me.

Call Uniden Tech Support and see what they have to say.

 

[scannersnstuff]

bearcat. uniden tech. support will play dumb. like i said so many time's before, i am not a uniden basher. out of the radio's i actively listen to, i have a bc898t,bcd396xt,bc246t,bc346xt and a gre psr-500 ! . i also am contemplating a bcd325p2. so i am no uniden hater. i just think that they dropped a major ball with the 436hp . i am anxiously waiting to see how the whistler trx-1 play's ball.

 

[RFI-EMI-GUY]

It's been suggested in the thread to try to use the negative battery terminal as a ground. I seem to recall someone tried a quick test and it was not helpful and maybe detrimental; which is quite strange.

While we know that you can sniff some signal in the area, it is not known that the signal there is infact the one causing the issue since there are no circuit measurements yet that give any indication of the source of the issue. It's still in theory possible that it is not an internal signal but an external signal, but the nature of the reports seems to indicate some fairly wideband noise. Not to say that could not be generated by something like DTV signals.

There is probably a DC power ground trace, logic ground trace and a seperate signal ground trace. The antenna connector is probably best place to bond the battery door. However, that might entail installing a shield over the entire rear cover.


Years ago I had a Regency MX3000 (an AOR rebadged) and found that its logic radiated a lot of noise pulses. I installed foil inside the entire cover to suppress it.

 

[bearcat]

There is probably a DC power ground trace, logic ground trace and a seperate signal ground trace. The antenna connector is probably best place to bond the battery door. However, that might entail installing a shield over the entire rear cover.


Years ago I had a Regency MX3000 (an AOR rebadged) and found that its logic radiated a lot of noise pulses. I installed foil inside the entire cover to suppress it.

Give it a go and let us know what you find.