Echo board?

Board from Alan 87. EPT36xx board.
Enabled or disabled makes audio muddy. Tested many times.
The same is in Galaxy 95t2 if I remember correctly.
Mike

First, you should have traced back and labeled all the wires leading from it before you pulled it out of that other radio. It would have been lot easier to duplicate than trying to find instructions. Second, since you’re not a tech, this mod should only be done by those with at least some experience. Third, because of space considerations echo board installs are usually reserved for larger framed radios. My advice is to forget all the hassles of an internal install and buy an EC 2018 Xtreme mic instead. It’s a much better solution that you can also use on other radios in the future. After the mic adjustments are set correctly, it will at least match if not outdo any internal echo boards.

I’ll agree with sp5it, muddy sounding and with age, turning the pots up makes it buzzy too.

Better choice would be one of the tiny boards like a Delta. Simple to hook up and tiny, bout the smallest I know of.

If you’re determined though, I have the wiring diagram for it here in the shop.

I don't think it would fit in a 520 either.

No it won’t. I didn’t see that part. Maybe if you wrap it up and lay it inside but I don’t know that I’d do that. Well I know for fact I wouldn’t do that, I mount all mine to the chassis of whatever I’m putting them in. But I have the wiring for it if wanted or needed.

Find you an echo board out of a Connex 4300-300, it’s made into the control knob. That’ll fit just about anywhere you put it.

I meant Midland Alan 87, radio popular in EU. Clone of many other

Jr750 said:

I do have all the wires label I made sure I did before pulling it out. I know I can go the echo mic route but not to crazy about dealing with the battery issue. And this will be a little project for me, all tech started somewhere, we all not born knowing how to drive we learn from mistake, level with me just trying to learn, my nearest shop is about 4 hours from me that I know of.

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Far be it from me to discourage anyone from trying something new. I’m all about DIY. It just sounded like you were in over your head and I wanted to give you an easy alternative. As a tech, I still prefer the EC 2018 Xtreme, battery and all.

I have one laying around been hot glued all over becareful with pins break off board easly

The letters "WEP" visible in the pic suggest that it was distributed by Workman. A board installed at the radio's factory would have header pins for the mike input and output. The hot-glued, soldered input/output wires are found only in aftermarket versions.

Looks just like the original analog echo board from the 1990s Galaxy and Connex radios. If so it will be marked "EPT0SSB" followed by a couple of digits.

If you labeled where the wires went you should be good to go.

73

Then if that don't work, type in those HA17324, MC3101, NM3008 numbers and get a PDF of them - you'd find them to be the main cluster hardware of how the older Echo systems and their techniques worked. Timing from one chip - gated into another with an audio chip buffering the input and output - similar to a Bucket Brigade I mentioned in a previous ancient thread - you see VR2 - changed the timing "gate" hence the delay and another located on the header pins took care of the depth of echo (how much of that gated sample was cycled) and the 4558 chip was your mic amp and your audio out buffer (how much got regenerated back into the brigade)

The missing parts on silkscreen I believe are for an external relay keying circuit to handle talkback and any TX RX modes (so you didn't echo the receivers own audio in some radios it can be used in - hilarious but ) ... the echo and the board required 8 volt regulation similar to the Galaxy, and yes to Mikes' (SP5IT) reference to the Alan radio - one version of ALAN the radio itself had a dual control knob that routed to the header and it had a switch on it -- like you'd have with the Volume On/OFF knobs of the older transistorized radios. Only one pole SHORTED the mic wires across the echo so you had no echo but the Mic amp worked like a buffer, then you turned it on powering the rest of the board to provide the hardware the means to provide the echo sample and injection into the Mic amp loop. The VR2 was for those (other) Alan radios that only had an ECHO switch - those then used VR 2 to control the amount of echo from a preset on the board itself - like a set of trimmer pots you use on some other echo mike handsets.

So there were variants of the board for the different radios they'd fit into - so it can be a lot of fun finding the data and schematic for this earlier version of the LT2 - but I digress.

It's not impossible - just tedious - and the PDF' datasheets are a blessing to help you determine the wiring of the header and the on off and short modes the thing needs as external support.