And the batteries are (apparently) only acting as an antenna for the noise that is present on the + terminal of the middle battery. You can take the batteries out and attach a piece of wire to that terminal and replicate the wide-band noise.
BCD436HP/BCD536HP: UHF Reception Issues due to Noise from Battery Compartment
- Thread starter bearcat
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And the batteries are (apparently) only acting as an antenna for the noise that is present on the + terminal of the middle battery. You can take the batteries out and attach a piece of wire to that terminal and replicate the wide-band noise.
Webheadfred
Member
Ascetically, it looks better under the foam. Why electrically would it be better over the foam?
I have no idea but in my case (no pun intended) going over the foam makes a difference. Others have reported under is fine
I'm leaning towards bearcat's hypothesis that it may have something to do with applying more pressure on the batteries, keeping them better seated. Maybe add another dimension to the experiment by testing weather stripping or adhesive foam blocks of various thickness...
Not an EE, but I'm thinking the conductive coupling of the batteries (via the foil touching them) is cancelling the noise. By merely placing the foil on the battery door without touching you are only slightly attenuating the noise...but I could be wrong.
Now that's friggin' funny!!!!
Not so much pressure but moving the shielding as close to the noise as possible
Webheadfred
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k3fs
Member
Not so much aesthetics, but my plan to put the foam under the battery was due to my keeping my spare SD card under that foam. I had cut a little sliver from the foam, and my spare SD card fit there perfectly. I may try placing the copper over the foam, put a piece of electrical tape on the copper and slit it to again slide my SD card in place. I am hoping that small slit does not cause a big leak of noise. I certainly will have enough tape to run some trials.
There is certainly some good input and feed back here, and that's a good thing.
There is certainly some good input and feed back here, and that's a good thing.
Look on the bright side. You'll have enough copper tape left over to experiment with relining you Aluminum Foil Deflector Beanie. 
I suspect that the center cell is acting as a radiator of the noise - specifically toward the left side of the cell. That's where the noise sniffs the strongest. So, putting the shielding under that cell only serves to act as a better antenna. Putting it over the cell acts like an attenuator.
The closer the proximity to that cell, the better the reflective (or perhaps disruptive) properties.
Because the shielding is making better capacitive coupling with the center cell.
The closer the shielding, the more capacitive coupling happening. An interesting test would be to try PRESSING IN on the battery cover of a shielded cover to see if that makes a difference.
He never has good luck receiving signals. :wink:
All supporting that it's the middle cell that is the (re-)radiator.
The difference is the proximity to the noise source which I believe is behind the middle cell on the left side. Not sure exactly what circuit is located there, but that seems to be the source.
That would likely only make for a better antenna and make the issue worse.
Not likely. It's shielding the noise source and the unintended battery/re-radiator. Bearcat tried shielding the entire rear case with no benefits. If it were a counterpoise improvement, that would have resulted in some benefit, but it didn't.
The first number after the z is the year of manufacture - 3=2013 / 4=2014 and so forth. 2016 models have a 6 in that position.
No. Several here have already reported many cell manufacturers.
I've been talking with 'cat' many times about this. I also did many of the same tests he has done (not sure who was first - nor does it matter).
I have also suggested many tests over the past several months - some with no benefit, and some like using the Airspy as a SA.
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Webheadfred
Member
Look on the bright side. You'll have enough copper tape left over to..... Aluminum Foil Deflector Beanie.
Actually Gary, I'll have enough copper tape left over to build an art-foamboard 440 log periodic antenna to squeeze a bit more performance from this radio and maybe hit a few more repeaters with the Icom. I assure you, I always look on the bright side and am enjoying this thread out of curiosity rather than any complaint with my radio. Enjoy your needling. Cheers.
I was not able to find any stray RF from either of my 436HP's.
I generally run them on exterior antennas but for the sake of helping out, I tried using a duck antenna and my RSSI is the same with or without an antenna when tuned to various UHF 460 MHz frequencies.
So that tells me something is different with the design or perhaps the SD card.
I'm using the U3 class SanDisk cards in mine and maybe that is why I don't see any noise in the band. I did try sniffing around with a RF probe I made and a spectrum analyzer just in case the noise shifted but nothing stands out.
So in conclusion, I won't be applying any extra shielding in mine as there is nothing to shield!
I generally run them on exterior antennas but for the sake of helping out, I tried using a duck antenna and my RSSI is the same with or without an antenna when tuned to various UHF 460 MHz frequencies.
So that tells me something is different with the design or perhaps the SD card.
I'm using the U3 class SanDisk cards in mine and maybe that is why I don't see any noise in the band. I did try sniffing around with a RF probe I made and a spectrum analyzer just in case the noise shifted but nothing stands out.
So in conclusion, I won't be applying any extra shielding in mine as there is nothing to shield!
Webheadfred
Member
I too use the SanDisk class 3 cards. After the copper install I could't tell any difference.
cellphone
Silent key.
Has anyone tried experimenting without batteries installed running on USB power? Is the noise originating from the SD card slot and using the batteries to act as an antenna?
Thank you very much for providing that info.
From what i have read on this thread so far the 2013 and 2014 units seem to have the issue. My 2015 and another with 2016 report not having the issue.
Great info to have when looking for my next unit.
FYI, the battery cover comes from Uniden without the foam block. I didn't see the foam on the Uniden accessories page, but you have to dig to find stuff there.
I was wondering about the possibility that it's the type of card, too. Maybe different types of cards communicate at different speeds, and certain cards generate 400 MHz signals. I never noticed the issue on my older 436, but was comparing a newer one to others and saw the same noise. I'm currently using a SanDisk Mobile Ultra 8GB card that is supposed to be more rugged than other cards.
I'll have to try the various cards I have and sniff for the noise to see if there is any change. I'll also try stock cells and Eneloop Pros to see if there is a difference.
Even if the foam doesn't come with the cover, you can use any foam (sticky or not) since the tape will hold it in place.
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