Hello to the list;
I am new to this reflector and would like to add a few comments regarding HV
cabling and safety.
Working in the high power RF power (industrial) power system business as
well as the safety compliance business, I have seen many HV interconnect
designs - both good and bad. In my opinion, most of the early amateur
amplifiers do not include proper safety and functional interlocks and
shields to keep both the operator and equipment safe.
It is easy to retrofit an cable connector cover/interlock over the typical
HV connector to inhibit or shut off the HV.
Amplifier chassis covers should also include such switches/interlocks.
HV cabling should be mechanically shielded to prevent exposure to the HV
conductor(s) if the insulation is compromised.
Many types of HV connectors are used and will pass typical safety compliance
inspections if they are interlocked. In fact my company has used modified
PL259/SO239 connectors to carry 7000VDC @ 2A (center pins and insulator
removed and the center conductor passes thru the SO239 into a specially
designed terminal). The type RG8 cable works well in this application and is
typically protected inside a Sealtite conduit. I know this is more that the
typical amateur has in their station but is a nice benchmark to achieve.
As far as other functional interlocks, there are lots of ways to prevent the
operator from doing stupid things but again, require additional circuitry
and hardware the original manufacturer has left out of the product design.
Food for thought.
Respectfully,
Steve Simons
W1SMS
Steven M. Simons
Tel.203.733.2110 Fax.203.746.1459
33 Ball Pond Road Danbury, CT 06811
Mailing Address: PO Box 8066 New Fairfield, CT 06812
FN31FK Lat 41.442718 Long -73.505777
(Ex KF6AJ, WA3WAS)
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Patrick Barthelow
Sent: Tuesday, September 14, 2010 8:47 AM
To: sam@owenscommunication.com; david.kirkby@onetel.net; amps@contesting.com
Subject: Re: [Amps] SHV connectors great, but where to find coax?
Sam,
Your HV encounter confirms my long held concern about the Millen HV plastic
connector. Appears to not be "hermetic sealed" with respect keeping the HV
inside, if a hand is ever brushed over the outside. Another failure mode I
saw for that connector, if the environment allows motion the B+ cable, as
I recall the plastic Millen connector shell is captured to the cable, by the
soldered large diameter center pin, to the relatively narrow conductor,
passing through a small hole in the shell. If that soldered connection
fractured, through fatigue flexing, etc the Hot, raw end of the B+ lead will
pop out of connector hanging in mid air, energized. Because of that
concern, I got (already had) some neat aftermarket shielding tubing. It
was a finely made, loose woven, metallic "tube" that looked and behaved
like a chinese finger trap toy. I ran that the whole length of the Drake
L-4B B+ lead from the PS chassis to, AND OVER the Millen connector, so as
to have a metal shi
eld completely surrounding the millen connector, to its base, and bonded
to the L4 Chassis. You could use a bananna plug Jack termination for the
shield wire to make for easy connects, and disconnects.
Best Regards,
73, de Pat Barthelow AA6EG
> From: sam@owenscommunication.com
> To: david.kirkby@onetel.net; amps@contesting.com
> Date: Tue, 14 Sep 2010 08:30:43 -0400
> Subject: Re: [Amps] SHV connectors great, but where to find coax?
>
> I think the right answer may be to MARK "HIGH VOLTAGE" Even when unplugged
> or some such. One of the "fit and proper" connectors for HV got me once
and
> I was very lucky. I had a rack-mount Henry 2002 220Mhz amp at a remote
> location. It has the HV PS in one enclosure and the PA in another. Between
> them was the HT lead that looked like a spark plug cable and had the
> Bakelite screw-on type connectors.
>
> I reached behind the PA to disconnect the BNC for the RX'er to hook up a
> service monitor and got the surprise of my life. The palm of my left hand
> brushed the HV "Proper Connector" and it arched into my hand and exited my
> elbow that was rested on a basement wall. Had by fate my elbow at the
> wall...the exit may have been my through my shoe. I had a painful hole in
my
> hand for months and a numb arm for a few days. Also had a nasty exit wound
> on the elbow.
>
> My point is that there may not be any "SAFE" HV connector for the
> uninitiated. Marking things with stickers spelling it out may make the
whole
> "which one" discussion unimportant. Good marking should avoid problems.
>
> Just my 2 cents,
> N9FUT
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Dr. David Kirkby
> Sent: Tuesday, September 14, 2010 6:51 AM
> To: 'AMPS'
> Subject: Re: [Amps] SHV connectors great, but where to find coax?
>
> On 09/13/10 05:46 PM, DAVE WHITE wrote:
> > "The Engineering Council in the UK would I expect strip someone of
> > their CEng status if an individual proposed such silly things."
> > But let's face it, the UK is becoming just about the most laughable
> example of the socialist Nanny State taken to the most extreme
> interpretation of the concept. I doubt if Henry V and Winston Churchill
are
> turning in their graves when they see modern Britain, I'm sure that
they're
> spinning like steam turbines.
> > This is the country where the Elf'n'Safety nazis (including rooms full
of
> overpaid, interfering, sanctimonious buffoons like the Engineering
Council)
> invade every aspect of our lives. I say Bollocks to the lot of them. If I
> want to build an HT lead with a PL259 on the end of it, then that's what
> I'll damn well do and I personally will take the risk. If I plug one end
> into the 6kV supply and the other into my right nostril then that's my own
> fault and my own responsibility, right?
> > Dave G0OIL (not SK, amazingly)
>
> cp $above-email /dev/null
>
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