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

[jeffm77]

Ok, I ordered the copper tape off of Amazon, will have it tomorrow sometime. Bearcat, just curious about something. In your tests, have you tried doing a limit search of the UHF band? I have noticed on my 436 VS any other radio, the "other" radios will find UHF signals and the 436 will just skip right over the frequency the "other" radio(s) find. Even with the radios side by side, the 436 seems to just skip right over as if there is no signal. The 436 even does it on County UHF freqs, just skips them. So, just wondering if the tape improved the searching also. Thanks.

 

[bearcat]

Ok, I ordered the copper tape off of Amazon, will have it tomorrow sometime. Bearcat, just curious about something. In your tests, have you tried doing a limit search of the UHF band? I have noticed on my 436 VS any other radio, the "other" radios will find UHF signals and the 436 will just skip right over the frequency the "other" radio(s) find. Even with the radios side by side, the 436 seems to just skip right over as if there is no signal. The 436 even does it on County UHF freqs, just skips them. So, just wondering if the tape improved the searching also. Thanks.

I have seen the exact same thing. With the shielded cover it comes to life. I am hearing DMR sites that totally disappear when I remove the battery cover. You should check that you do see SCR in the lower left of your screen. That would indicate you are screening out certain freq ranges.

 

[jeffm77]

No, I do not have SCR on my screen. So, basically what is happening is, RF leakage is coming through the battery compartment and traveling up to the antenna, therefore, resulting in the interference and hissing noise. Like everyone has said, you use an antenna not directly connected to the radio, the interference disappears, go back to the antenna directly on the radio, it's back. Well, according to Amazon, my tape order will arrive by the end of the day tomorrow. We shall see what happens after.

 

[SCPD]

Other Option

Bit of an update, if anyone is interested.

I took measurements (Keysight BSA and a BB60C to confirm) with the stock battery cover, no cover and after application of a conductive coating and found that indeed the coating does help. These measurements were taken with eneloop pro batteries installed.

While I am not in a position to release the instrument data (due to a NDA clause) I have no problem with stating if you have access to a proper conductive coating and the ability to do the job right, you will be happy with the results.

Anne-britt

 

[bearcat]

Bit of an update, if anyone is interested.

I took measurements (Keysight BSA and a BB60C to confirm) with the stock battery cover, no cover and after application of a conductive coating and found that indeed the coating does help. These measurements were taken with eneloop pro batteries installed.

While I am not in a position to release the instrument data (due to a NDA clause) I have no problem with stating if you have access to a proper conductive coating and the ability to do the job right, you will be happy with the results.

Anne-britt

Yes coating would be a great way to do this. Sounds like you have a business opportunity. Buy a bunch of battery covers, treat them and sell them as a third party enhancement. (LOL) Are you at liberty to say a percentage of noise still coming through? If not, thanks for your input. Keep us posted on your over the air experience. Cover ON vs Cover OFF

 

[SCPD]

Yes coating would be a great way to do this. Sounds like you have a business opportunity. Buy a bunch of battery covers, treat them and sell them as a third party enhancement. (LOL) Are you at liberty to say a percentage of noise still coming through? If not, thanks for your input. Keep us posted on your over the air experience. Cover ON vs Cover OFF

Might be a business opportunity for someone (not me), you never know, your post has been popular.

I am just fortunate to work for a firm that encourages the engineering staff to "play" by offering us up to 10% of paid time each week to work on personal projects. Just happened to see your post yesterday and noticed that we were spraying today.

One can of course get pretty decent results at home using a aerosol conductive coating but it can be messy and the thickness is hard to control.

Not able to disclose the SA data as it, even our personal projects, are covered by an NDA.

Got to do some "real world" testing now. Will keep the thread up to date.

Thanks go to you for the post, wish there were more technical related threads like this here.

Anne-britt

 

[AggieCon]

So the next thing to explore is applying this to the entire back case. Non-conductive tape could be placed over if there are any concerns about shorting to the internal components.

Perhaps Darunimal could try it out when he puts his back together.

 

[tajens]

Hobby Lobby sells copper tape. It's used for stained glass. There's a downside
it's only 1/4 inch wide so I had to cut about 10 strips for the battery cover.

 

[bearcat]

So the next thing to explore is applying this to the entire back case. Non-conductive tape could be placed over if there are any concerns about shorting to the internal components.

Perhaps Darunimal could try it out when he puts his back together.

I did the entire back case during my testing and the results are nil. My rear case is still shielded and the only thing that matters is the battery cover. When you probe the radio with an SA the only place there is any noise floor increase is at the middle battery (this was confirmed but another poster). Now if someone wants to try theirs go at it, but I found that to do nothing at all.

 

[AggieCon]

How about the front?

 

[bearcat]

How about the front?

I never tried the front. There are so many openings with screen & speaker that there are not many areas to apply the tape. Also I cannot find any noise coming from the front. Certainly somebody could try it.

 

[bearcat]

Hobby Lobby sells copper tape. It's used for stained glass. There's a downside
it's only 1/4 inch wide so I had to cut about 10 strips for the battery cover.

How does the radio work now?

 

[SCPD]

When you probe the radio with an SA the only place there is any noise floor increase is at the middle battery (this was confirmed but another poster).

Based on my measurements, these were my findings as well.

Don't remember what SA, I believe it was KevinC was using but the ones I used are calibrated to accepted standards.

Anne-britt

 

[bearcat]

Based on my measurements, these were my findings as well.

Don't remember what SA, I believe it was KevinC was using but the ones I used are calibrated to accepted standards.

Anne-britt

That is good to know. I do not have an SA. I used any AirSpy SDR. It works but certainly not a test bench quality device.

 

[KevinC]

Based on my measurements, these were my findings as well.

Don't remember what SA, I believe it was KevinC was using but the ones I used are calibrated to accepted standards.

Anne-britt

Mine is current on the calibration as well. :wink:

 

[microx]

Quarter-wavelength away?

Is there a possibility it has to do with the batteries being roughly 5-1/2" - 6" or so away from where the ground shielding for the SMA mount ends inside the antenna? Does this UHF issue change when someone uses the included adapter and then puts a BNC antenna on? A quarter-wave antenna for 450mhz is 6.25", and for 470mhz is 5.97". I'm not sure if this has anything to do with it. (and why it doesn't seem to on other scanners of roughly the same dimensions) Most likely it doesn't, but since we're discussing this, I thought I'd throw that observation out there.

 

[garys]

Which tape did you order on Amazon? They have a bunch of choices.

Also, can someone post a picture of how they covered their battery cover? It doesn't look too complicated, but I'd like to see how others are doing theirs.

Ok, I ordered the copper tape off of Amazon, will have it tomorrow sometime. Bearcat, just curious about something. In your tests, have you tried doing a limit search of the UHF band? I have noticed on my 436 VS any other radio, the "other" radios will find UHF signals and the 436 will just skip right over the frequency the "other" radio(s) find. Even with the radios side by side, the 436 seems to just skip right over as if there is no signal. The 436 even does it on County UHF freqs, just skips them. So, just wondering if the tape improved the searching also. Thanks.

 

[k3fs]

Is there a possibility it has to do with the batteries being roughly 5-1/2" - 6" or so away from where the ground shielding for the SMA mount ends inside the antenna? Does this UHF issue change when someone uses the included adapter and then puts a BNC antenna on? A quarter-wave antenna for 450mhz is 6.25", and for 470mhz is 5.97". I'm not sure if this has anything to do with it. (and why it doesn't seem to on other scanners of roughly the same dimensions) Most likely it doesn't, but since we're discussing this, I thought I'd throw that observation out there.

I have noticed the same poor UHF performance using an SMA mounted antenna or a BNC mounted antenna using the adapter. Both SMA and BNC antenna options see an equal improvement when the shielded battery case door is on.

The 436 will receive better than my 396Xt when using the same outside mounted antenna. In portable use, the 396 does better, but that difference is decreasing.

 

[bearcat]

Which tape did you order on Amazon? They have a bunch of choices.

Also, can someone post a picture of how they covered their battery cover? It doesn't look too complicated, but I'd like to see how others are doing theirs.

If you look backwards in this thread folks have posted pictures.

 

[bearcat]

Copper Tape

Do we have anybody who used the copper tape and seen an improvement? I can only remember posters who used aluminum tape like I did.