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Re: YAESU G5400 Lessons Learned





Douglas Braun & Nadia Papakonstantinou wrote:
> 
> Ironically, the Radio Shack azimuth rotors have no limit switches,
> and when they reach the end of travel the motor simply stalls.
> But the motor's current draw only increases 10% or so when this happens,
> thanks to the general wimpiness of the motor windings and the transformer...
> 
> Doug
> NA1DB


This is a valid protection scheme, well known in the small
induction motor world.  It's called an "impedance-protected"
circuit.  In many cases, it is FAR superior to a motor circuit
which simply smokes when the 2-bit limit switch fails.  These
impedance-protected motors are produced up to 20-30 hp and are
perfect for applications where stalls are common.  They usually
have a constant-torque characteristic and are particularly
useful when excessive torque would do mechanical damage during
a stalled condition.

This may sound like heresy, but my experience with both the RS
and Yaesu rotors leads me to believe that the RS rotors, FOR THE
MONEY, are better engineered.  A pity RS dosn't offer an EL rotor
or a large AZ rotor.

John   W5EME


> 
> At 08:13 PM 9/27/01 , Jim Sanford wrote:
> >Ladies and Gents:
> >
> >In several private discussions on these things, I've been asked to
> >publicly post the following:
> >
> >The G5400 system suffers from some design problems.  Specifically, a
> >"stall" of the elevation rotor can take out the motor, power
> >transformer, and THEN the fuse.  It happened to me, and to 2 others that
> >I personally know of.
> >
> >Here's why it happens:  The control box is over fused.  The elevation
> >rotor has no overload protection.  The limit switches prevent it from
> >grinding into a stop, but if it is overtorqued because a pine tree grows
> >into the path of your 2m antenna, there is no protection.
> 
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