436/536 RF overload from nearby ham radio damage resulting in receiver fail. Q2 and Q3

[radioman2008]

Greetings.

I have multiple 436/536HP scanners. recently I keyed up a ham radio transmitter where its antenna was within a foot or 2 of the scanner antenna and it damaged some of the 436/536 receivers. some scanners no longer receive anything, others sensitivity is reduced significantly. one was sent in for repair to Uniden and it was returned repaired, having replaced Q2 and Q3 transistors.

does anyone know the transistors' actual part numbers? I would like to repair the remaining scanners myself.

thank you.

 

[a417]

Greetings.

I have multiple 436/536HP scanners. recently I keyed up a ham radio transmitter where its antenna was within a foot or 2 of the scanner antenna and it damaged some of the 436/536 receivers. some scanners no longer receive anything, others sensitivity is reduced significantly. one was sent in for repair to Uniden and it was returned repaired, having replaced Q2 and Q3 transistors.

does anyone know the transistors' actual part numbers? I would like to repair the remaining scanners myself.

thank you.

If you're planning on taking them apart to fix them, I'd do that now - read the part numbers and cross reference - and then order them yourselves.

As the units are still being actively sold by the manufacturer, the schematic & BOM might still not be public knowledge.

 

[dave3825]

it was returned repaired, having replaced Q2 and Q3 transistors.

I would also be asking the location of those transistors.

does anyone know the transistors' actual part numbers? I would like to repair the remaining scanners myself.

If you can find the locations, you may be able to obtain the part number.

 

[radioman2008]

I just took it apart. Q2 and Q3 are on the RF board
they are SMT, not surprised.

I'm trying to google the part numbers but as of yet nothing standing out

it appears.... a small "s" next to a capital "WV" so kidna looks like sWV and then sideways it looks like 99 on one end

 

[pro92b]

Take a look at the eBay listing for an Infineon BFP420 transistor linked below. Look at the pictures and try to match them with the part in the radio.

20PCS BFP420 SOT343 25GHz Transistor NEW | eBay

Find many great new & used options and get the best deals for 20PCS BFP420 SOT343 25GHz Transistor NEW at the best online prices at eBay! Free shipping for many products!

www.ebay.com

If this is the correct part I don't suggest you buy from a Chinese vendor - there are other eBay listings and this device is available at DigiKey as well.

 

[dave3825]

I just took it apart. Q2 and Q3 are on the RF board
they are SMT, not surprised.

I'm trying to google the part numbers but as of yet nothing standing out

it appears.... a small "s" next to a capital "WV" so kidna looks like sWV and then sideways it looks like 99 on one end

Maybe snap a close up pic and post it?

 

[radioman2008]

Maybe snap a close up pic and post it?

I tried, even tried my digital SLR and a magnifying glass with it. no luck, the transistor is too small.

 

[dave3825]

t appears.... a small "s" next to a capital "WV" so kidna looks like sWV and then sideways it looks like 99 on one end

So mine is open and looks like lowercase s followed by VM. Mine sure looks like 45 on the end. If you take it outside and look with magnifying lens and tilt in the light the numbers are slightly easier to read when the light hits it the right way.

Any idea where this goes? Found it laying loosely under VT2. Feels like rubber.

Also does your IC107 look like this or did uniden spill solder?

 

[prcguy]

Maybe go here and request the part #s?

https://info.uniden.com/twiki/bin/view/UnidenMan4/PartsRequest

 

[GTR8000]

Maybe go here and request the part #s?

https://info.uniden.com/twiki/bin/view/UnidenMan4/PartsRequest

Perhaps you didn't look at the last request that was actually answered. That page sadly died along with Paul, if not years prior.

 

[prcguy]

Perhaps you didn't look at the last request that was actually answered. That page sadly died along with Paul, if not years prior.

You could still contact Uniden to get the P/N or a price on the part.

 

[GTR8000]

Okay.

 

[dave3825]

Disregard my question about the rubber as it seems that is what held the lousy rubber flap the covers the ports on the side.

 

[Ubbe]

There where a guy who replaced those two amplifier transistors in the 436 with better specification ones. Uniden use the cheapest ones they can find that then hasn't the best specifications. I think the guy posted it here at RR with the info of what transistors to use. If it wasn't here then go to scanner.ru (if it's still available to access) and make a search for BCD436.

/Ubbe

 

[radioman2008]

So mine is open and looks like lowercase s followed by VM. Mine sure looks like 45 on the end. If you take it outside and look with magnifying lens and tilt in the light the numbers are slightly easier to read when the light hits it the right way.

Any idea where this goes? Found it laying loosely under VT2. Feels like rubber.

my IC107 is well soldered, nothing like what you show

Also does your IC107 look like this or did uniden spill solder?

View attachment 146131

 

[dave3825]

my IC107 is well soldered, nothing like what you show

I had a feeling. I cleaned it all up and reassembled and listening to it right now.

 

[Remon]

Could this be the reason I had 6 deaf UBCD3600XLT's within 3 years from different sellers, while other people don't have any issues with this scanner?

I live near a broadcasting tower with very high power transmitters (FM, DAB, DVB, paging, ham repeaters) and after reading this thread I now suspect all 3600's got damaged as soon I powered them up for the first time..

 

[prcguy]

Could this be the reason I had 6 deaf UBCD3600XLT's within 3 years from different sellers, while other people don't have any issues with this scanner?

I live near a broadcasting tower with vrty hugh power transmitters (FM, DAB, DVB, paging, ham repeaters) and I suspect all 360p's got damaged as soon I powered them up for the first time..

You would have to be really close to the transmitting antennas to receive any damage like less than 10ft away.

 

[RFI-EMI-GUY]

You would have to be really close to the transmitting antennas to receive any damage like less than 10ft away.

The total uncorrelated power could be significant in the aggregate.

 

[radioman2008]

I THINK IM ONTO SOMETHING, perhaps this info is what is needed or maybe you know more about transistors than i do and could shed some light on whats better.......

I went to youtube, found a video called SMD component codes in it he referenced s-manuals dot com /smd

not sure if the links will work but here they are

Marking of electronic components, SMD Codes WV, WV***, WV-***, WV0, WV2, WV3, WV4, WV5, WV9, WVY. Datasheets AX5505R37, BAT54A, BAT54S, BAV23A, BAV23C, BAV23S, BFQ67W, BSS84AKS, BZT52C47, BZX284-B4V7, PZU15BA/DG, RP131K511D, RT9016-33PB, SMAJ9.0CA.

Marking of electronic components, SMD Codes WV, WV***, WV-***, WV0, WV2, WV3, WV4, WV5, WV9, WVY. Datasheets AX5505R37, BAT54A, BAT54S, BAV23A, BAV23C, BAV23S, BFQ67W, BSS84AKS, BZT52C47, BZX284-B4V7, PZU15BA/DG, RP131K511D, RT9016-33PB, SMAJ9.0CA.

www.s-manuals.com

Marking of electronic components, SMD Codes VM, VM-, VM-***, VMW, VMp, VMt. Datasheets 2SA2088, 2SA2090, BZB84-B6V8, PZU12B2A, RP130K221D, RT9818C-50PB, SMAJ150CA.

Marking of electronic components, SMD Codes VM, VM-, VM-***, VMW, VMp, VMt. Datasheets 2SA2088, 2SA2090, BZB84-B6V8, PZU12B2A, RP130K221D, RT9818C-50PB, SMAJ150CA.

www.s-manuals.com

Its very easy to look up, there is a grid where you can select the 2 digit code below


one user here referenced their transistor has code sVM (45 sideways) while mine says sVW (99 sideways)
maybe a clue will be common data between those 2 codes. ( the VM code doesnt show anything obvious)
when I look up mine (WV) the data page shows several package designs, my Q2/Q3 are the BAV23 package design it has 4 pins, and one of the 4 pins is fatter than the others, this is true for both Q2/Q3
it says the BAV23 is dual high voltage switching diodes, package SOT23

I goto Ebay and find some sellers selling BAV23 components (the BAV23 listings also referred to as an SOT143), some have the 4 pins with one fatter.
I found a motorola version MRF9411LT1
perhaps this is the better than average version someone else mentioned?

​

MRF9411LT1 Product details​

​

​ The RF Line NPN Silicon Low Noise, High-Frequency Transistors Designed for use in high gain, low noise small–signal amplifiers. This series features excellent broadband linearity and is offered in a variety of packages.

MRF9411LT1 Datasheet(PDF)

Part #: MRF9411LT1. Download. File Size: 309Kbytes. Page: 17 Pages. Description: NPN Silicon Low Noise, High-Frequency Transistors. Manufacturer: Motorola, Inc.

www.alldatasheet.com

what do you think?