[Elecraft] Blown ammeter question used with KX1/gelcell/solar panel

Doug Forman doug at dougforman.com
Sun Nov 28 15:22:04 EST 2004


I use inexpensive (now discontinued) Radio Shack bench volt and 
ammeters when I am combining rechargeable batteries and a small solar 
panel for QRP portable use.

(btw, Volkswagon places small 12v solar panels in the windshield of 
some of their cars when shipped from overseas to keep the batteries 
trickle charged...  these are ruggedly built, are labeled for 
3.2w/18.8v/170ma, and have a cigarette-lighter plug attached...  bought 
mine for around $9 on eBay).

In a "senior moment" (cough) I recently mistakingly hooked 12v from a 
small 0.8ah gelcell battery (that I connect to my KX1) directly across 
the + and - terminals of my 0-1000mA meter.  After the smoke cleared, 
and I disassembled the case, I noticed that I had melted a wire 
connecting the meter to a binding post.

The ammeter is a simple meter with three binding posts...  0-500, 
0-1000 and common.  It sold for around $13 at Radio Shack (part number 
22-401) but was discontinued over a year ago (I've tried to just buy 
another one with no luck).  Inside the small plastic case is the meter 
and wires, no other parts.

Internally, the meter has no part markings other than the word "CHINA". 
  The black (hookup) wire from the meter terminal was soldered to a bare 
wire covered with loose fabric insulation, which was then soldered to 
the common (black) binding post (this was the wire that melted), and 
the red (hookup) wire connects to a bare wire which connects the (red) 
0-500 and (red) 0-1000 binding posts and is covered with loose fabric 
insulation close to the 0-500 binding post (the red side is still there 
and did not melt).

Any thoughts, suggestions and wisdom from the "wizards of the list" 
would be most appreciated - as this question may be a little off-topic, 
perhaps replies should be sent to me off-list (or not?) your choice...

72,

Doug  N7BNT



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