BCD436HP/BCD536HP: Terrible UHF reception and emitting RFI

[takheng]

I purchased a new BCD436HP on Amazon and got it yesterday. What I was disappointed is that the uhf performance really bad with portable handheld antenna. Also, I notice it was emitting RFI that similar to my SDS100 as state in my previous post.
SDS100: - Noise floor very high when using handheld antenna

I compare my new BCD436HP to my SDS100 as well as my well perform BCD396XT. BCD396XT blew them out. My new BCD436HP is even worst than my poor performance SDS100 in portable configuration.

I put a Motorola XPR7550e as an RSSI meter side by side to probe the interfere that BCD436HP emit. Normally, the Motorola radio show -127dBm at an idle channel. When my new BCD436HP power up, the RSSI went up to -110dBm. That indicate the unit was emitting at least 10 to 20 db RFI, and wipe out the weak signal.
I attempt to use an SDR and a short antenna to locate the interfere. The RFI seems coming from both the top (near "Uniden" logo) and the bottom of the unit, but might not from the center battery. I use eneloop rechargeable battery. I also tried to power by usb power only, same result, the RFI didn't eliminate.
I applied copper tape on the inside of the battery lid, but that doesn't help to eliminate the RFI and no improvement on reception.

I don't know when the unit was manufacture. The SN start with 376Z1800xxxx. I doubt whether it is manufacture earlier that doesn't have C1 capacity install on the board. I was so unlucky that I got the defective device from Uniden twice. Really disappointed.

So what should I do next to improve my BCD436HP reception? I live in Asia and shipping back to Uniden take months and cost much money. I haven't encounter other problem like RTC or display issue. Is it worth sending it back to Uniden for repair? Or is it possible to just take it apart and install C1 capacity by my own?

 

[Ubbe]

Or is it possible to just take it apart and install C1 capacity by my own?

There where several design changes to the circuit board. One didn't had anywhere to solder a capacitor. Try and find those RR posts with pictures and serial number ranges that are affected.

What does the 436 specification say about the noise floor? Uniden will probably say that it works to specs and send it back to you unrepaired.

/Ubbe

 

[takheng]

There where several design changes to the circuit board. One didn't had anywhere to solder a capacitor. Try and find those RR posts with pictures and serial number ranges that are affected.

I took it apart just now, founding that C1 capacitor is installed on the board. But it keep emitting the RFI. Weird!

 

[WaLT3R_Wh1T3]

I purchased a new BCD436HP on Amazon and got it yesterday. What I was disappointed is that the uhf performance really bad with portable handheld antenna. Also, I notice it was emitting RFI that similar to my SDS100 as state in my previous post.
SDS100: - Noise floor very high when using handheld antenna

I compare my new BCD436HP to my SDS100 as well as my well perform BCD396XT. BCD396XT blew them out. My new BCD436HP is even worst than my poor performance SDS100 in portable configuration.

I put a Motorola XPR7550e as an RSSI meter side by side to probe the interfere that BCD436HP emit. Normally, the Motorola radio show -127dBm at an idle channel. When my new BCD436HP power up, the RSSI went up to -110dBm. That indicate the unit was emitting at least 10 to 20 db RFI, and wipe out the weak signal.
I attempt to use an SDR and a short antenna to locate the interfere. The RFI seems coming from both the top (near "Uniden" logo) and the bottom of the unit, but might not from the center battery. I use eneloop rechargeable battery. I also tried to power by usb power only, same result, the RFI didn't eliminate.
I applied copper tape on the inside of the battery lid, but that doesn't help to eliminate the RFI and no improvement on reception.

I don't know when the unit was manufacture. The SN start with 376Z1800xxxx. I doubt whether it is manufacture earlier that doesn't have C1 capacity install on the board. I was so unlucky that I got the defective device from Uniden twice. Really disappointed.

So what should I do next to improve my BCD436HP reception? I live in Asia and shipping back to Uniden take months and cost much money. I haven't encounter other problem like RTC or display issue. Is it worth sending it back to Uniden for repair? Or is it possible to just take it apart and install C1 capacity by my own?

I’m not too far removed from just a beginner myself, but I’ve also seen that using some copper shielding tape on the inside of the battery cover makes a noticeable improvement

 

[takheng]

I’m not too far removed from just a beginner myself, but I’ve also seen that using some copper shielding tape on the inside of the battery cover makes a noticeable improvement

I've tried to apply copper shielding tape on the inside of the battery cover, without much improvement on reception. It seems that the RFI noise is coming from somewhere internal, rather than from battery compartment. And C1 capacitor is found installed on the board, but it still continue to emitting interfere.