Very good productive discussions on the topic.
I am a firm proponent of a shielded HV cable for safety, and accompanied by the
design considerations being discussed.
What I have seen out there, in the Home brew amp world as a rule, rather than
an exception, is often a single unshielded HV wire connecting the PS box to
the RF deck, sometimes even automotive store aftermarket HT Ignition wire.
Not comfortable with that at all.
Other times with the hyper flexible rubber, perhaps silicon rubber HV test prod
wire perhaps only 3-4mm OD. That scares me, and I would love to see a real
world test of test prod wire that has been impacted, pinched, run over by
castor wheels of 100 lb PSs. and that sort of thing. I have seen wire that is
pinched hard under wheels, or other heavy equipment, and sometimes have seen a
nearly undetectible split to the core wire inside, a complete violation of the
insulation from the outer surface to the hard, stranded wire inside, that could
easily be missed on a visual inspection.
If you took a test sample 3 mm HV test prod wire and say, hit it semi lighly
with a hammer against a concrete floor base, you would do compression damage
the insulation to some degree depending on the hit, and it might not be all
that visible. That test may simulate a hard rollover by a narrow castor wheel
of a Heavy PS. It would be enlightening to injure such wires to varying
degrees and then carefully HI POT test the wire in the direct vicinity of the
"injury" so see if say, a 10 KV rating was highly compromised.
Best Regards,
73, de Pat Barthelow AA6EG apolloeme@live.com
http://www.cq-vhf.com/vhf_highlights/2010_vhf/2010_summer_vhf/2010_summer_vhf_echoes_barthelow.pdf
MOONBOUNCE YURI'S NIGHT
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