[Milsurplus] Hot PE-73 relay redux

[WA5CAB at cs.com]

Jim,

#20 is not a suitable replacement for 2 x #26.  2 x #26 is the same cross 
section as #23.  #20 is the same cross section (and resistance per foot) as 2 
x #23, or therefore 4 x #26.  So if you could wind the same number of turns 
of #20 on the coil, it would have a little more than half the resistance of 
the original coil (the mean turn diameter will be greater).  And draw 
nearly twice the current.  Since you probably can't get the same number of turns 
on (since it would result in a coil roughly twice the diameter of the 
original - fewer turns per layer and more layers), the coil current will at a 
rough guess be closer to 3x and it will get close to 3 times as hot.

Also, not to pick a nit or anything, but solenoids are not relays.  Or not 
primarily.  A solenoid produces a mechanical movement from an electric 
current.  Relays mechanically close and/or open an electric circuit when 
energized with an electric current.  Some solenoids do also function secondarily as 
relays.  But not in golf carts.  Internal combustion engines often have an 
electrc starting motor with a small gear that engages a larger gear on the 
engine.  There are two common methods to engage the small gear with the large 
one - centrifugal and solenoid.  Centrifugal engagement mechanisms are 
commonly called by mechanics "the Bendix".  After the company that built the 
first commercially successful ones I think.  Starter motors equipped with a 
Bendix are controlled by a relay, not a solenoid.  Direct engagement starters 
are usually controlled by a solenoid, whose secondary function is as a relay.  


Or to cut to the chase, golf carts do not have starter solenoids, and 
neither do dynamotors.  They have relays.

In a message dated 08/15/2011 23:47:16 PM Central Daylight Time, 
mcenfalz at humboldt1.com writes: 


> At Dennis W7QHO's recommendation, I dropped a golf cart starting solenoid 
> in there and it works well enough to get me on the air. Runs cool, but 
> doesn't match the mounting. Good band-aid, though.
> 
> I opened up the coil and it's a masterpiece of simplicity - big 1/2 inch 
> square copper contacts driven by a fat scramble-wound coil wound on a 
> bobbin. Looks to be ~#26 wire; 2 wires wound parallel and parts of it were pretty 
> crispy. The progressive short theory looks to have been correct. Should be 
> a simple fix once I get the new wire. I have a new 15# roll of #20 that I 
> may try just because it's handy.
> 
> Cheers!
> 
> Jim Falls
> K6FWT
> Eureka, CA

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