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Summer 2004 Issue |
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 Photo A. The USM-174 military-surplus power meter and the attachments found in the top lid of the power-meter case: meter attachment cord to bolometers; and (left to right) the gray devices are 8–12 GHz, 12–18 GHz, and 18–25 GHz, and the black device is 100 MHz to 8 GHz. |
MICROWAVE By Chuck Houghton, WB6IGP Microwave
Test Equipment, Power Meters, and |
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The wild winds of opportunity can be a dreaded thing if you do not know how to verify the operational status of test equipment at swap meets and flea markets. What I am talking about here is the method of making a good choice in picking up a bargain, rather than taking a chance and possibly selecting a great doorstop—an item that is not functioning and might prove too costly and/or take too much time to repair.
Such was the case with my USM-147 meter. All I
could lose in this case, however, was time itself, as it was free.
Normally I look for more exotic meters to upgrade my work bench. In one
case I found an HP-436 power meter for $25. I did not have test equipment
with me to verify its operation, but for $25 the gamble was a good one. I
arrived back at my QTH, tested it, and it worked. For more expensive
devices, read on for my recommendations on how to test them at swap meets
and flea markets. If you are told a piece of test equipment for sale is in working order and you know the seller is trustworthy, then you are in good shape. Another option is to purchase a unit with the explicit understanding that if you take it home and it doesn’t work, you can return it and get your money back. Give it a shot if your best instinct tells you it’s okay, and then barter the best you can to reach a price that is acceptable to you and the seller. I would limit this scenario, however, to items that are not very costly.
Testing the equipment at a swap meet or flea
market is the best of all possible options. Most swap meets do not have AC
power available to do a simple check on a piece of equipment to determine
whether it’s working or not. For most small items (excluding transmitters)
that you may want to check, bring along a 12-volt battery with a set of
clip cords to power them up. Is the unit working on receive as a basic
function? For those items requiring 110-volt AC power to test them, a
simple 200-watt, 12-volt input AC inverter can be used. I would not carry
these power units around, but rather keep them in your vehicle while
looking for items of interest. Then take the power unit to the equipment
or the equipment to the power, depending upon what can be worked out with
the seller. A $10 or $20 deposit or even a QSL card given to the seller
can be effective and a sign of good faith if you take the unit to your
vehicle to test it. Click here to return to Summer 2004 highlights Click here to subscribe to VHF _________________ © Copyright 2004, CQ Communications, Inc. All rights reserved. This material may not be reproduced or republished, including posting to a website, in part or in whole, by any means, without the express written permission of the publisher, CQ Communications, Inc. Hyperlinks to this page are permitted.
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