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Our Active Preselector allows you to pick-up transmissions or frequencies at 10 times the distance. Use with our HandiCounter^1 or

R-10 Interceptor"

10MHz- 1GHz

Tunable over 5 octaves s995.

Tone Counter Model TC200

NEW! Ideal companion for use with the R10 EM

Communications Interceptor" to measure sub audible signalling tones off the air. The TC200 can also be used with scanners and communications receiver to monitor sub audible tones.


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Number 20 ûn your Feedback card

Michael J. Ceser KB1UM c/o 73 Magazine 70 Route 202 North Peterborough NH 03456

Fixing Walkies

Probably the most common piece of ham equipment today is the 2 meter HT. Especially since the advent of the no-code Technician license, the popularity of walkies has increased, I haven't met very many hams who don't own walkies.. So, it seems reasonable that some of those radios are going to have problems. Let's look at the kinds Of problems which tend to occur and at what we can do about them.

What a Cad

Nickel-cad, that is. If you've owned your walkie for more than a year or two, chances are you either have had or soon wiH have trouble with the battery pack. No matter what the industry says, those darned NiCd batteries just don t last very long. By now, everybody knows that you should run the battery all the way down before you charge it up again. Bui even if you do that, a year or two is about aii you can ask for. i have met hams who had properly working packs more than three years old. but not very many My own experience has been pretty dismal, despite the fact that i follow all the rules, is it possible to actually fix a bad battery pack?

The Tech Answer Man

Well, sometimes. In fact. 1 just fisted One in my cordless drill a few weeks ago, and it's still going strong. I've described before how to zap a NiCd cell, but I'D give a brief repeat here ior those who missed it.

There are two fixes which have worked for me. For shorted celts, take a DC power supply and charge up an electrolytic capacitor The cap should be several thousand microfarads or more; a 100-microfarad cap just won t do it+ Charge it to 15 volts or so, being careful to ensure that the cap is rated for more than that. Don't forget to watch the polarity. Now, again watching the polarity, connect it across the shorted cell, + to + and -to Don't use clip leads, because their resistance can limit the current flow. Just touch the cap's leads to those of the celli. You should get a nice little spark. Disconnect the cap and measure the cell's voltage. If you get anything much above zero, you've done it; the cell should now charge properly. If the cell Is still shorted, try again, it took me 10 tries to fix that drill's cell.

For cells which aren't shorted but just won't hold a charge, I've found that a few seconds of high-current charging can sometimes do wonders. By high current, I'm talking about a couple of amps, not 201 A current-limited DC supply works fine. This fix Isn't as dramatic as the other one. but It might save your ailing pack

Neither of these fixes can be done without getting access to the terminals of the bad cell; you can't do this stuff through the other cells in a pack

After you've fixed a bad celt, you must balance all the other cells before you try to recharge the pack. If you don't, the bad cell mosi likely will fail again very soon. To balance the pack charge the bad cell to, say. f volt. Then, discharge all the other ones through a flashlight bulb, one cell at a time, until they all read 1 volt. Reassemble the pack and charge it normally, and it Should work fine if the cells are not loo far gone

By the way, most NiCd packs have built-in thermal fuses that are designed to prevent fires in packs which inadvertently get shorled at their terminals, perhaps by keys or coins in a pocket. If the pack has in fact died Immediately after experiencing such a short, a new thermal fuse may be all you need. I don't know where you can buy new ones, but perhaps one of you does. If so, please tell me and I'll pass it along. But please don1t even consider simply shorting across the fuse and putting the pack back in service. Even small NiCd packs can deliver enough current into a shon to cause serious injury. That's why manufacturers always warn you not to put NiCd cells into holders meant for ai-kalines; the holders have no fuses, because alkalines don't present nearly as much risk.

Insert Here

Sometimes, NiCd cells simply are beyond redemption. And new packs Irom the manufacturers are awfully expensive. Besides, my experience has been that most manufacturers use exceptionally poor cells. When a battery pack goes bad six monlhs after you buy the rig, you sure don't want to shell out for another one just like ft I Luckily, severat aftermarket companies advertise inserts for walkie packs. These are pre-connect-ed cells which fit into your original plastic shelf. I tried one in the FNB-17 pack for my Yaesu FT-411 ana it worked great! If you can crack the original pack open carefully enough that it can be snapped or glued back together, you would do well to try an insert. Often, soldering is required but, hey, we're hams, right? By the wayf the one brand of cells I've had good results with has been Sanyo. I've seen, and in fact own, Sanyo cells that are five years old and have been abused, yet silll work fine. 1 have no idea why theirs are so much better, but I strongly recommend you buy an Insert made with them, You1 It wind up with a better pack, at about 1/2 to 1/3 the price of a new, original-equipment pack.

Where's the Magnifying Glass?

OK, your walkie is getting power but it still doesn't work right. Walkies are basically no different than other radios, but they do have some unique characteristics which make them a bit harder to work on. The most obvious one is that they are getting awfully smalt these days. Back when the tCOM IC-2AT and Yaesu FT-208R were atl the rage, you still could fit your fingers into the case. Nowadays, things have gotten to the point where surface-mounted components and ribbon cables dominate. How do you fix something like that?

Sell your product in 73 Amateur Radio Today Call Dan Harper today... 1-800-274-7373

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