EFJ 4-series / issues

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Joined: Thu Jul 20, 2017 11:48 pm

EFJ 4-series / issues

Post by KB9UIY » Fri Jul 21, 2017 8:59 am

Good morning all. I've been lurking here for a number of years, but, finally decided to come out of the shadows. I've messed around with various flavors of P25 gear for the last ~15 year; mostly XTS, but also includes the EFJ 5100 series.

I just recently acquired another 5100, and it is displaying some weird behaviors. Seeing as how this seems to be where the best and brightest EFJ minds hang out, I thought I'd open up a discussion, and see if anyone has any thoughts. I don't have much in the radio, but would love it make it play. It's absolutely gorgeous - in GREAT shape.

Radio Specifics:
EFJ 5100
Arrived with 4.8.10, I upgraded it to 4.14.05, using Express Updater.
Was using PCC 2.8.2, now using 2.10.2 since the update.

The issues I'll describe here were present before the firmware upgrade. I was hopeful that it may have helped. It's an interesting project, and I have always loved these radios. I apologize in advance if I am duplicating any parts of this topic. I did a reasonable amount of searching, and didn't find anything with the same issues.

Issue #1: The radio, on 442.000 and 443.000 range repeaters, goes "microphonic" on receive. However, on a repeater in the mid 444.000 range or simplex in the 446 range (or GMRS channels), it does not. After the volume is turned up about 1/3 of the way, this starts. It becomes an echo, then a howl, then a really loud howl, then starts clipping and cutting itself out. One interesting note, attaching a speaker mic eliminates the issue. It does almost sound, both with and without the speaker mic attached, that I can hear my fingers moving on the radio.

Issue #2: A couple of times, the radio went "dumb". Wouldn't receive or transmit, though the red light came (and stayed on) when the PTT was pressed. I seem to recall this being an issue somewhere along the line. And the UI board possibly being bad. But, I figured I'd add this to the discussion, since, not sure if it is somehow related to the other issue.

If all this unit becomes is a parts source, that's ok too. But, I figured I'd open some discussion, as I am planning on doing some playing with this platform. Thank you in advance, if anyone has any ideas!

Posts: 31
Joined: Fri Apr 17, 2015 1:51 pm

Re: EFJ 4-series / issues

Post by W0VNE » Sat Oct 07, 2017 3:38 pm

Its just a guess but being microphonic sounds like an iffy soldering connection. If you have a microscope it might be worth looking at the PCBs and seeing if anything looks unsoldered or cracked. Its always nice to have some known good boards you can swap to localize the issue.

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