BCD436HP Close Call Capture sensitivity

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Valeriy

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Well, I reside in a signals-rich environment and usually get scores of Close Call hits every day
and night but, powering the 436 with a power bank, I have noticed a sort of Close Call Capture sensitivity
reduction, so to speak: when the unit is connected to a power bank, the number of Close Call hits drops
nearly to zero, and rises again only when the unit is running on the internal batteries power.
Could that be just a coincidence, or it has already been noticed by someone else?
 

jonwienke

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There are 2 possibilities:

The power bank's internal circuitry is generating RF interference, and desensitizing the scanner's receiver. If this is the case, putting a ferrite bead on the USB cable to block RF coming through the USB cable may help, or perhaps you could find a cable with one already attached. Or get a different power bank with better quality internal circuitry.

If you are using the stock antenna, the USB cable may be affecting reception. Try using a different antenna, preferably one outdoors.
 

troymail

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Given the well documented issues many of us have with interference in at least the UHF band (and have applied various solutions like copper tape and other "fixes" to the battery door), it wouldn't surprise me in the least if you're having some noise or interference issues.
 

jonwienke

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You're confusing a totally different issue. The OP's problem only occurs when a particular external power device is plugged in.
 

Valeriy

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There are 2 possibilities:
The power bank's internal circuitry is generating RF interference, and desensitizing the scanner's receiver. If this is the case, putting a ferrite bead on the USB cable to block RF coming through the USB cable may help, or perhaps you could find a cable with one already attached. Or get a different power bank with better quality internal circuitry.
.
I've thought of that, and checked the power bank with an IBQ 102 counter, but it looks like the power bank doesn't generate any detectable EM noise.
And yes, I already use an USB cable with a ferrite choke near the micro-USB plug.
I haven't tried yet to use an other power bank, instead. I'll try that out.
Thanks for the reply.
Regards.
 

Valeriy

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Given the well documented issues many of us have with interference in at least the UHF band (and have applied various solutions like copper tape and other "fixes" to the battery door), it wouldn't surprise me in the least if you're having some noise or interference issues.
Yes, some months ago I have put an aluminum foil inside the battery bay door, after reading a post here.
Regards.
 

Ubbe

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If possible, detach only the cable end at the charger and see if the scanner outputs RF interference from the cable, as it works as an emitting antenna.

/Ubbe
 

Valeriy

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If possible, detach only the cable end at the charger and see if the scanner outputs RF interference from the cable, as it works as an emitting antenna.
/Ubbe
Well, I verified that, and using a shorter USB cable, which I keep wrapped in two loops in order to further reduce its linear size, and still with a clip-on ferrite choke near the mini-USB plug, the number of daily (and nightly) Close Call hits is nearly as high as when the 436 is running on the internal batteries power.
Thank you very much.
Regards.
 
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