Electra Bearcat III Scanner

One of the perks of my job is people will occasionally ask us to recycle their functional electronics. Which often translates to: “More toys for Marc”. A number of months ago I pulled this old scanner from the bin, mostly because I was drawn to its aesthetics. It’s an Electra Bearcat III, early 1970’s vintage. I saved it from the bin thinking at the very least, I could use the housing for another project at some point. It is simply too cool looking to be tossed in the trash.

Behold, a Bearcat

Behold, a Bearcat

After sitting on the shelf for months, last night I decided to tear into it and see if I could make it work. Now, it should be noted that I know nothing about scanners, radios, what-have-you. This proved to be an advantage, since it seemed a smart move to document everything for my own reference.

The controls:
Fairly straightforward, there’s a Volume/Power knob, a Squelch knob, a toggle swithch for Auto scanning or manual channel selection, and on/off switches for each of the 8 channels. Red LEDs serve as channel indicators.

The enclosure is held together by a single screw in the back, and the cover slides off to the rear. Looking down at the main board, there are the crystals in an array on the lower left.

There are 8 crystals, one per channel. There are also two modules; A and B, which correspond to the installed boards on the bottom of the main board. Here’s a close-up of the crystals, all installed in Module B. You can see some of the frequencies printed on the tops of the crystals.

On the underside of the unit there are two boards for the High and Low Bands. So plugging a crystal into one side or the other determines which board it connects to. Pretty cool. I would assume that means if I could find the parts, I could possibly get Citizen and other bands by replacing those boards.

Close-up of the boards, one covers a band from 30-50MHz, and the other covers 150-174MHz.

Okay, now that we’re familiar with the internals, I can start messing with things, right? Wrong. Despite my desire to tear into things all willy-nilly, discretion told me it might be a good idea to look over some documentation first. Thanks to the internets, I managed to locate a PDF of the manual!

Also, taking Adam Savage’s words of wisdom to heart, I made sure to take thorough notes.
Adam Advice

First, I pulled each crystal, and noted frequency and location in module. After that I found a list of frequencies in my area, and jotted down any that sounded like they’d be interesting. Then since I misread the manual, I banged my head against the wall trying to sort out how to make the channels “be the correct frequency”… It doesn’t exactly work like that, and it took me almost an hour to figure out that I had misinterpreted what the manual was telling me. Somehow I got it into my head that with certian combinations of placing crystals in the modules, I could “tune” it. I was close, but it doesn’t quite work that way. For a crystal radio, you need the crystal with whatever frequency you are interested in. Without the desired crystal, it isn’t going to pick up that frequency. The End.

After cross referencing the list of frequencies I had, and placing them back into correct module, I figured I was out of luck. None of the crystals in either module had picked up the slightest trace of activity. It was closing in on midnight, and I had work in the morning. Dejected that I either had a dead scanner or a bunch of bunk crystals, I decided to call it a night. I liked the LEDs blinking though, so I left it running in my lab, figuring I’d poke at it this evening.

Just as I was drifting off to sleep, I heard voices coming from down the hall. As I got up to investigate, I heard an ambulance dispatcher speaking from my lab! Hey! It works after all!

What did I learn?
That taking the time to really understand documentation makes a big difference. I learned that sometimes thing are actually more simple than they appear. From researching I learned a bunch about the various radio bands and what’s on them. And, as I told Molly this morning before I wrote this blog: “Sometimes you have no clue what you’re doing, but that shouldn’t stop you from getting in there and doing it.” I think that may be the one of the most important lessons that anyone can learn. While it’ll occasionally blow up in your face, the experience is almost always worth it.

So now what?
As it turns out, crystals are still fairly easy to come across. A number of them can be found on eBay for about $5 each. It’s a possibility that I’ll shell out the coins if I can somehow verify that I will be able to pick some interesting things with it. I have to imagine that the local HAMS would have that information, some forum digging is in my future.