If you have another scanner, you can test for the noise this way. Tune the second radio to 350.000Mhz AM mode. Note amplitude modulation not FM. Remove the battery cover. Place the antenna of the second radio on the positive side of the middle battery. You should hear an increase in noise. Do the same test on 460.000 and 500.000 Mhz. This test will a least prove that you have the noise. Many of the tests you mention have been discussed in the 540 posts on the this list. None of them fixed the problem but the shielded door. That being said move forward with your tests. You may hit on something somebody missed.
BCD436HP/BCD536HP: UHF Reception Issues due to Noise from Battery Compartment
- Thread starter bearcat
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I can tell you if the anti-static bag has zero ohms it has little no effect. I have been following this thread for a while. I had no Aluminium tape well at least not till about 8 minutes ago. I tried a bag wrap around the Eneloop battery. That seems to provide the best difference but it still what I call the margin of error. Ie moving the radio 1/1000 of an inch in any direction provide the same difference. I did what seem to sound marginal better when driving, but again I could pin to that or different atmospheric conditions.
I also tried a business card cut in half between the battery and the cover. To see if was the force of batteries getting the push in. Then a business card cut in half wrap in the ESD bag.
Today I got my tape from amazon. I put it on. I post back either this weekend or next week with what I saw.
Just to clarify. The radio is generating unwanted RF noise. That noise is making its way to the receiver (antenna). The noise is louder than most weak signals. By shielding the door the noise is reduced and the antenna does not see it (or at least most of it). Hence the receiver will hear weak signals. On DMR is it so dramatic that you will not ever know a signal is present. While on analog not only can I hear signals that were never heard prior, it also clears up the noise/static on weaker signals it could hear. Keep in mind we are only talking UHF and maybe a bit on VHF. The radio on 800 has always been great. So RF shielding is the goal.
JamesO
Member
Shielding the battery door should not be the goal, this is just a bandaid.
The source of the signal leakage needs to be identified and addressed. My guess is something in production may have been missed or gone wrong?
Possibly a wrong component, missing screw, missing ground or bent or improperly installed shield.
I realize you want to fix or resolve the problem with your radio, but if they all do not exhibit the problem, something is wrong with the production or assembly.of some subset of radios.
It is possibly the leakage is bad enough that the radio would even be FCC Part 15 compliant??
The source of the signal leakage needs to be identified and addressed. My guess is something in production may have been missed or gone wrong?
Possibly a wrong component, missing screw, missing ground or bent or improperly installed shield.
I realize you want to fix or resolve the problem with your radio, but if they all do not exhibit the problem, something is wrong with the production or assembly.of some subset of radios.
It is possibly the leakage is bad enough that the radio would even be FCC Part 15 compliant??
I could not agree more, but right now the shielded door is the answer. If you can find the issue or get Uniden to tell us then have at it. So far no one has found another answer. I said from the beginning that some component is missing or misaligned or whatever, but I have no way of finding it. All though their will be those that disagree I think they all have the issue to some degree.
As far as Part 15 compliance I have no idea what the criteria is, but I know it is no that stringent of a spec.
jeffm77
Member
Bearcat, can you e-mail me direct. Got a question for you. Can't find your e-mail address.
Yes I understand all that what puzzling is by shielding the door the noise can not get out the back. But it not begin redirect so what is puzzling is that it not going up into the body of the scanner.
I am listing to a analog frequency in 400mhz. One of my coworkers was a radio guy for navy. He also puzzled as to why the block single those not just get to antenna on inside. Only the thing we came up is that there is shielding perhapes above the battery Compartment. So the Basically helps trap the noise.
Perhapes the tape is a working as an antenna instead of blocking.
I got a bcd125at might try tape on battery door off that unit and see what it those.
You did not mention your results now that you have the door shielded?
The shielding is not acting as an antenna. It is prohibiting the middle battery from acting as an antenna. That is where the noise is being generated. If you remove the batteries and run the radio on USB power the noise is greatly reduced. Most agree that since the tape must go over the foam we have create a capacitor.
As for posting like I said.
I am waiting to post to eliminated any interference from atmospheric conditions that affect the RF waves as they travel which will affect how good your receive. ie a longer enough sample size to be sure of what I am seeing. It the same as what I did when testing the ESD bag and Business card.
As for a capacitor, unless your putting tape above and under the foam your not creating a capacitor. Two layers or several layers of the tape is not creating a capacitor unless you are putting material between the layers. To create a capacitor you need two conductors and an insulator. I can not speak for others but on my setup no capacitor was created. My Tape is all above the foam.
As for removing the middle battery. I run the radio several times with no batteries off USB and never notice a big difference.
I suggest this test to get some immediate results. According to RRDB you have a large DMR Con+ system in your area. Setup a custom search from 451 - 473, Mode NFM, Step Size 6.25. Run the search. You should see the radio decoding the DMR data stream from the control channels. While the scanner is stopped on the data stream remove the battery door. Does the signal disappear? Do this same test on all of the data streams you find. If any of the signals disappear with the door off. You have fixed the problem. Also I assume you are using an antenna on the radio, not an external outside antenna. Note the test will work whether you have the the DMR upgrade or not.
You have to look at it different. The bottom battery is connected to the negative/ground part of the radio by the external metal sleeve of the battery which is then covered by the insulating sleeve of the battery. With the shielded cover in place the center battery couple into the shielded cover then that couples into the bottom battery. Because of the series connection the capacitance is cut in half. With the shielding on top of the foam the distance is reduced between the shield layer and the battery sleeve layer increasing the capacitance and effectiveness.
Comments above are from a mechanical perspective and how in a very theoretical approach capacitance can be created reducing what is radiated into the antenna and shunted to ground.
Puzzling that the reception and shielding varies from unit to unit across all the members reporting no change or great improvement. While I tried one layer of copper shield tape under the foam I can't say I noticed any improvement on weak signals. It has been an interesting thread.
Mike
I'd like to see someone experiment with using a piece of wire to connect the CASE of the center battery to the others, without any other shielding (or with the battery door removed). My theory is that shielding isn't even what's happening here (otherwise it wouldn't matter whether the tape was above or below the foam), but rather there's a stray signal on the center battery that has no path to ground, and the tape (only when installed above the foam) is acting as a conductor across all three batteries, giving the signal that path. I realize the outer battery cases aren't any more grounded than the center battery case, but there has to be a reason why above the foam vs. below the foam yields such a big difference in results.
A complimentary test would be to take a unit that is showing improvement with the "shielding" in place (above the foam), and cover the shielding tape with a layer of vinyl electric tape (or something non-conductive). The "shield" would then still be in place, but without anything conductive touching the battery cases. If my theory holds any water, the poor reception will return.
A complimentary test would be to take a unit that is showing improvement with the "shielding" in place (above the foam), and cover the shielding tape with a layer of vinyl electric tape (or something non-conductive). The "shield" would then still be in place, but without anything conductive touching the battery cases. If my theory holds any water, the poor reception will return.
I seem to remember that someone stated you should NOT take the cover off the battery and attach a wire between them. There is a voltage potential on the sleeve of the battery. Even if that did work it would not be a very convenient solution for changing batteries.
Oh sure; I'm suggesting it as an additional diagnostic, not as a permanent fix.
So Thursday around this time I put this tape https://www.amazon.com/gp/product/B01FROBUXE/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
On the battery door over the foam, I place two layers.
Where I notice the biggest difference was on
472.23750 127.3 PLBC Police 1County Police 1
470.35000 107.2 PLFD 2 NorthCounty Fire F-2 Response North
I did notice some improvements on mainly on office side not so much on dispatch
471.50000 131.8 PLBC Police 2County Police 2
I did however notice very minor improvements on
472.08750 103.5 PLFire/EMS DspCounty Fire/EMS F-1 Dispatch
471.17500 110.9 PLFD 3 SouthCounty Fire F-3 Response South
472.51250 114.8 PLFD 4 FD/PDCounty Fire F-4 Fire / PD Backup Ch
471.02500 118.8 PL FD 5 EMS OpsCounty Fire F-5 EMS Operations
472.68750 123.0 PLFD 6 LZ OpsCounty Fire F-6 Medivac LZ Control
The system for all these channels is analog systems. The two channel with the biggest difference were also the one that serves the further area from where I am at in country on daily basis. I main interested in this because when I travel I notice the P25 system seem to come in bad. Sometime in next 2 to 3 years, the county is switching to P25 system. So I, of course, want to make sure I am getting the best receptions I can.
The before and after examination were done with radio in the same place with the same diamond SRH77CA antenna
The wife, about as non-technical as you can get, notices a difference in scanner over the last few days. So it not just me that notices a difference.
Transmission had less static. I was able to listen to the radio at the much lower volume level. The improvement was noticeable in the three place I listen to the scanner. At work in concrete and steel building. At home and in the car.
Now as for the capacitance with the outer battery. Sorry not buying that on my scanner I picking up zero voltage across the battery terminal and outer skin of battery. And resistance shows full resistance.
I did take a peek into the radio and the back of the radio those have metal shell above the battery area to the top of the radio. On the side of the battery. but said metal has round holes likely to do adjustments. it possible that shielding that battery door is simply keep what noise the batteries or sd card make from reaching these hole and messing with the reception of the radio.
That my opinion as some who been dealing with RF and Electronics since 1992.
On the battery door over the foam, I place two layers.
Where I notice the biggest difference was on
472.23750 127.3 PLBC Police 1County Police 1
470.35000 107.2 PLFD 2 NorthCounty Fire F-2 Response North
I did notice some improvements on mainly on office side not so much on dispatch
471.50000 131.8 PLBC Police 2County Police 2
I did however notice very minor improvements on
472.08750 103.5 PLFire/EMS DspCounty Fire/EMS F-1 Dispatch
471.17500 110.9 PLFD 3 SouthCounty Fire F-3 Response South
472.51250 114.8 PLFD 4 FD/PDCounty Fire F-4 Fire / PD Backup Ch
471.02500 118.8 PL FD 5 EMS OpsCounty Fire F-5 EMS Operations
472.68750 123.0 PLFD 6 LZ OpsCounty Fire F-6 Medivac LZ Control
The system for all these channels is analog systems. The two channel with the biggest difference were also the one that serves the further area from where I am at in country on daily basis. I main interested in this because when I travel I notice the P25 system seem to come in bad. Sometime in next 2 to 3 years, the county is switching to P25 system. So I, of course, want to make sure I am getting the best receptions I can.
The before and after examination were done with radio in the same place with the same diamond SRH77CA antenna
The wife, about as non-technical as you can get, notices a difference in scanner over the last few days. So it not just me that notices a difference.
Transmission had less static. I was able to listen to the radio at the much lower volume level. The improvement was noticeable in the three place I listen to the scanner. At work in concrete and steel building. At home and in the car.
Now as for the capacitance with the outer battery. Sorry not buying that on my scanner I picking up zero voltage across the battery terminal and outer skin of battery. And resistance shows full resistance.
I did take a peek into the radio and the back of the radio those have metal shell above the battery area to the top of the radio. On the side of the battery. but said metal has round holes likely to do adjustments. it possible that shielding that battery door is simply keep what noise the batteries or sd card make from reaching these hole and messing with the reception of the radio.
That my opinion as some who been dealing with RF and Electronics since 1992.
Any reason for two layers? Did one not suffice? Curious as I used a similar product as a single layer with improvement but not beyond adding a second if it attenuates the noise more.
Doc W4EMS
On the battery door over the foam, I place two layers.
Doc W4EMS
On the battery door over the foam, I place two layers.
Using aluminum shielding tape, I had two layers. I cannot really say for sure how much you need. Just put on two it cannot hurt. Now with copper it appears about 6 layers are best, more than 6 and things get worse.
When I removed the protective cover from my batteries with the shielding tape touching all three the radio would not power up. I was happy I did not hurt the radio. I went no further with that test. Did you try any testing with DMR reception. Also while you are listening to the improved freqs. Take the door off while they are transmitting. You should hear more noise or even a total signal drop out.
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Just to add another data point, I applied 2 layers of this foil tape to the inside of my battery door today:
https://www.amazon.com/gp/product/B00DY9IXFI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
Then I monitored a busy fire ops channel on 453 MHz and saw no detectable difference with the foiled door vs without it. This ops channel is analog, about 30 miles distant, and with the RS800 duck I was averaging 2 to 3 bars. There is a fair noise floor on this signal as one might expect on a duck antenna, and the signal to noise ratio did not audibly change when removing the foiled door. I put both layers of foil tape over the foam pad, however with the first one I left a small section of the paper backer material in place so that the tape would not stick to the foam pad.
Perhaps this isn't the right type of foil tape? Or could it be that the tape needs to actually stick to the foam pad? I have some copper foil tape on the way. I will try 6 layers of it just to see, but I don't hold much hope for it. I think my 2015 vintage BCD436HP is just one of those units that's not affected by this issue, as that fire ops signal is also unchanged if I run the radio on USB power with no batteries. It's sn 376Z58000xxx. I bought the radio new from Amazon. It's never been returned for any reason, still has the older bluish backlight and original RTC battery, both of which are still working fine after a year of average use.
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https://www.amazon.com/gp/product/B00DY9IXFI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
Then I monitored a busy fire ops channel on 453 MHz and saw no detectable difference with the foiled door vs without it. This ops channel is analog, about 30 miles distant, and with the RS800 duck I was averaging 2 to 3 bars. There is a fair noise floor on this signal as one might expect on a duck antenna, and the signal to noise ratio did not audibly change when removing the foiled door. I put both layers of foil tape over the foam pad, however with the first one I left a small section of the paper backer material in place so that the tape would not stick to the foam pad.
Perhaps this isn't the right type of foil tape? Or could it be that the tape needs to actually stick to the foam pad? I have some copper foil tape on the way. I will try 6 layers of it just to see, but I don't hold much hope for it. I think my 2015 vintage BCD436HP is just one of those units that's not affected by this issue, as that fire ops signal is also unchanged if I run the radio on USB power with no batteries. It's sn 376Z58000xxx. I bought the radio new from Amazon. It's never been returned for any reason, still has the older bluish backlight and original RTC battery, both of which are still working fine after a year of average use.
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