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Re: FT-847 Disaster - THE PAIN!

Hi Dave, and the group:

I quite understand your frustration, particularly after what you 
probably think you did to cause the problem seems so dumb in retrospect.

  Be rest assured you aren't the first and probably not the last to hook 
up the power supply leads the wrong way.....being mere humans it's real 
easy to do. Other things, like your problem are easily caused as well.

In the commercial world of radio's (R/T) the Tait/Motorola/etc rigs have 
all sorts of "idiot proofing" built in....the most useful ones being 
FAST blow fuses or circuit breakers combined with a very large (>100 
amp) suicide diode in the main power leads to remove power really, 
really fast in the event of a major problem.

In all my amateur installations I have included a similar system 
utilising high current diodes removed from old car alternators and an 
inline fuse rated at only a few amps above the rigs maximum current 
requirements, all this placed in the main power line to the rig.
  It saved my '817 from instant suicide when I hooked it up in a mates 
boat, not realising that it was a 24 volt system. the (5 amp) fuse blew 
almost instantly and saved the rig. This system also has a thyristor and 
15 volt zener to guard against over voltage since I was told that the 
finals can die real fast with over voltage. It (the '817) is still 
working ok.

So I would recommend that a similar system should be provided for ANY 
rig that has an external power source, why yaekencom don't do this as a 
matter of course is beyond me!


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