The Radio Information Board

Anyone else have same problem (?) and if so any idea if the following is more likely a faulty engineering design or a bad component run: I've had good results with many VHF 5100 portables (mostly legacy models) over time but have been stumped by three VHF radios all *rev.4* with faulty RX stemming from what appears to be (3) faulty high current SMDs (all 27uh) in RX circuit near TX/RX split. Problem was identified as being caused by heavy ambient VHF RF nearby at time of failures. I've tried with zero success to locate the components, as EFJ will only sell said new components (27uh inductor, 1.2A, case style 0805) to EFJ-authorized service centers; EFJ says solution is to buy another radio or buy a replacement RF board. Last avenue before giving up so far was searching Mouser, Digikey, and the like with no such components being available without buying a reel and waiting a few months. If anyone has access to sell said components either generic or EFJ Part number 542-5010-019, I'd love to buy quantity 12 or 15.

You might want to check out globalsources.com (SMD Inductor) or Hammond Mfg.

Ever have any luck? I have a Rev 4.x.x with a RX sensativity issue also. I attempted to swap the RF board with a Rev 1.x.x and the radio errored out on test. So, the low RX radio is just a TX radio!

Any luck with this?

I also have a deaf vhf RX... Not sure of the rev of the board but any direction on where to look on it when I open it again would be appreciated.

Mike.
VE7KED

Any luck with this?

I also have a deaf vhf RX... Not sure of the rev of the board but any direction on where to look on it when I open it again would be appreciated.

Mike.
VE7KED

Well I popped the radio back open with the hope that this info might help identify what I have.

The board says it is VHF and on the top of the board etched is the manufacturer - CALAMP (c 2004)

Under above where it says REV it says 5A811

the bottom of the board has a sticker with barcodes:

P6A811
S34004812

Does this help someone identify the board? The RX is deaf but TX appears to function as expected.

Mike.

Hi all.

I too have the same issue here with a vhf rev 4. I've isolated my issue to what I believe to be an LNA, refdes u39, associated with D4. I'll ping a few folks to see if I can get a copy of the schematic or at least part numbers. It's hot to the touch, not normal under most circumstances for small signal stuff. If it's the same issue with others radios, I'll offer to help with repairs. I do SMT stuff all day long, so no fear on the size of components.

Will

It may be a good idea to post the serial/series number for the radios having this issue. Maybe we can figure out if it came from a specific plant or lot.

Post ALL BUT THE LAST FIVE DIGITS as some manufacturing info is encoded there.

f4t

5110F2305T-xxxx

Don't have a new enough service manual to decode this. using the old template, I assume this was made in the 23rd week of 2005. Does the T=Texas?

Will

Alright, I ordered the appropriate parts today, actually enough for 10 radios. I'll report on results later this week or next when they get here. If it's a success, I'll offer to do repairs if anybody needs help. Will work for beer .......

Will

willbartlett wrote:5110F2305T-xxxx

Don't have a new enough service manual to decode this. using the old template, I assume this was made in the 23rd week of 2005. Does the T=Texas?

Will

Just to help out a little here:
The T means it was made at their MTI Contract Mfr.
The C means it was made at their CTI Contact Mfr. (the better of the two IMO)

Evening All. So, I can certainly confirm that this device U39, Avago model MGA-71543 is the cause of the unhappiness with my radio. I was concerned about D4, which as if happens , is a fet capable of handling 3A of current.. I'm not worried about it.

I'm going to look at sensitivity, but a quicklook shows it back in the realm of -115db for usable quieting, or approximately .35uV if you're calibrated that way. needed -55dbm to get that before, or 400uv

Once I get real numbers I'll post results. Looks like we might have a fix for these radios.

Also, Most of the inductors in the front end should be rated at 1A or better, so they're unlikely to be at fault. I need to look into the clamping diode fix for these so the repair won't get undone.

Will


Update.

Checked the thing out and it's at spec.

So, I you aren't comfortable repairing your own radios, I can do surface mount work, do It all day for my real job. If anybody is interested in a repair, Email me off list and we can discuss how to get some of these back to life.

Will

Excellent. I had one of these fry out like that just out of the blue. I was driving along noticing there was no traffic and the RX sensitivity was crap. I was lucky enough to have a friend with connections help me out through his shop or it would have cost a small fortune.

Hey,

I obtained the part as you described and I now have a fully functional reciever. Thanks so much. I have had this radio sitting in a box for nearly two years. I sure am glad I never parted with it. The wait had definately paid off. Nice 5 dollar fix

Cheers,

Mike.