jeffm77
Member
So, what you are saying is you removed the foam, put the foil tape down, then replaced the foam, then put more foil over top of the foam?
BCD436HP/BCD536HP: UHF Reception Issues due to Noise from Battery Compartment
- Thread starter bearcat
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troymail
Silent Key
Best results appear to be --- place a layer (in my case two) of the foil on the inside of the flat part of the battery door directly OVER the existing foam pad.
Signal strength of the noise, not intended signals.
At least for me, the signal strength of an intended signal doesn't change with the shielded door on or off.
If I have time and the curiosity level rises enough, I'll do a desense test this weekend.
jeffm77
Member
I think a desense test would be helpful, KevinC.
I've put one layer of tape on my battery door and haven't seen an appreciable change, but I don't have a lot of signals coming in tonight at all. I'll see how it behaves tomorrow when I'm commuting into the city.
I had two "and a half" layers (one going one direction where two 1" strips covered the door neatly, and the second the other direction which left a gap in the middle, which I then covered with a third strip) but removed the top layer and a half when it became apparent it wasn't doing much.
I just tried doing the PWR check with the shielded door on vs off, with my radio holding on a quiet channel (no traffic) in the 422 MHz range. With the door off, the PWR reading was in the 120s. With the door on, the reading is consistently 111-115.
You have batteries installed, correct?
Yes, fresh Sanyo eneloop XXs. And a Diamond SRH-789 antenna.
Great news. Glad you are now a believer too.
Do you have 450 - 470 mhz activity in canada?
Not where I am at home (30 miles into the Rocky Mountain foothills), but in the city, yes. There's a DMR DT3 control channel at 461.85 which I can pick up reliably here at home but there's no appreciable improvement on that signal with the shielded door on vs the door off vs no shielding at all.
To be fair, it hasn't been root caused yet, so we don't know if it takes a certain condition to show up or if it even affects all units.
But it is a great discovery!
Tried again with the radio in RF Power Plot mode tuned to 450.0000.
Shielded door on: 170
Shielded door off: 190
While I was preparing to write this post, a transmission came in on 154.830, from a transmitter quite close to me (under 5 miles line-of-sight, on a mountaintop).
Shielded door on: 406
Shielded door off: 405
This is what my door looks like, latch tab at top of pic:
Shielded door on: 170
Shielded door off: 190
While I was preparing to write this post, a transmission came in on 154.830, from a transmitter quite close to me (under 5 miles line-of-sight, on a mountaintop).
Shielded door on: 406
Shielded door off: 405
This is what my door looks like, latch tab at top of pic:
What setting did you in sample rate?
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100ms. That shouldn't affect anything, but stranger things have happened.
This is what I get. I get 1-2 bars.
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D
darunimal
Guest
A couple of Quick Thoughts here:
First 3 batteries, only 1 end of the 6 inches or so of battery is grounded, is this a antenna? (of course its only grounded once, since the other end is positive)
Second, if any one else want to reproduce the injection of noise for themselves, simply Edit a Custom Search between 440-472mhz and watch your scanner crawl through the search range, not really a crawl but not 80steps a second either. For proper control, the manufacturer included a SMA-BNC adapter in the box, put it on and watch the crawl, burping, jumping, writhing begin. To stop it, Turn On Attenuation, watch it fly.
Third, I noticed when taking the scanner apart, you have a mother and daughter board. there is a shield over top the daughter board (it the one that sits against the scanner rear case) between it and the mother board (power sourced board) . There's an extra opening at the bottom lip of the shield, where it mates with the case with feet. It this where some spurious injection coming off the demodulator refracted by the shield down to the battery, exponentially multiplying itself
http://forums.radioreference.com/un...iden-x36-simulcast-performance-thread-10.html
First 3 batteries, only 1 end of the 6 inches or so of battery is grounded, is this a antenna? (of course its only grounded once, since the other end is positive)
Second, if any one else want to reproduce the injection of noise for themselves, simply Edit a Custom Search between 440-472mhz and watch your scanner crawl through the search range, not really a crawl but not 80steps a second either. For proper control, the manufacturer included a SMA-BNC adapter in the box, put it on and watch the crawl, burping, jumping, writhing begin. To stop it, Turn On Attenuation, watch it fly.
Third, I noticed when taking the scanner apart, you have a mother and daughter board. there is a shield over top the daughter board (it the one that sits against the scanner rear case) between it and the mother board (power sourced board) . There's an extra opening at the bottom lip of the shield, where it mates with the case with feet. It this where some spurious injection coming off the demodulator refracted by the shield down to the battery, exponentially multiplying itself
http://forums.radioreference.com/un...iden-x36-simulcast-performance-thread-10.html
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k3fs
Member
I can respect the fact that not EVERY radio has bad UHF reception. With the small sample size of radios in my area, I am not aware of any that do not show this problem. Again, I am not going to get too tangled up in chasing numbers. There are a couple of you tube videos that show the improvement that is being received and are exactly identical to what my results, and others have been. It's not like that non receivable signal is going to be full scale. It is now a signal you can receive and decode and in most cases have much less noise on the signal.
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