[AMRadio] Millen High Voltage Connectors


W1EOF w1eof at hamnutz.com
Mon Jan 9 19:22:27 EST 2006


They are fine when the connection is inside an interlock protected cabinet.
Not very conveinent for troubleshoting or working on the equipment, but they
work fine. If the connector is outside the cabinet then naturally it must
not have an exposed terminal.

I also agree on the RF connectors for high voltage. Even if it's marked it
is too easy for you, or someone else to make a fatal mistake. This is made
worse by using coax (a common RF cable). That's just bad design.

Spend a few extra bucks and get the proper connector, one that's safe. Life
is too short to mess around.

73,

Mark W1EOF

> -----Original Message-----
> From: Brett gazdzinski [mailto:Brett.gazdzinski at mci.com]
> Sent: Monday, January 09, 2006 6:56 PM
> To: 'Discussion of AM Radio'
> Subject: RE: [AMRadio] Millen High Voltage Connectors
>
>
> What is wrong with ceramic feedthroughs?
>
> I don't think I like the idea of using RF connectors for high voltage,
> what happens if you or someone else mix it up with RF antenna or output
> stuff?
>
> Brett
> N2DTS
>
> -----Original Message-----
> From: amradio-bounces at mailman.qth.net
> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Ed Swynar
> Sent: Monday, January 09, 2006 4:01 PM
> To: Discussion of AM Radio; boatanchors at mailman.qth.net
> Subject: Re: [AMRadio] Millen High Voltage Connectors
>
> Hi Dave,
>
> I solved the problem of HV B+ arc-overs here by exclusively using NOTHING
> but good-quality SO-239 coax receptacles, & RG-8 coax lines for the B+
> leads, terminated in good-quality PL-259's...
>
> Works like the proverbial charm --- have yet to encounter ANY arc-over
> failures since adopting this approach universally at my station
> in the late
> 70's...
>
> ~73~ Eddy VE3CUI - VE3XZ
>
> PS: Emphasis on the words "...good-quality" --- NONE OF THAT CHINESE JUNK
> here!!!
>
>
>
>
>
>
> ----- Original Message -----
> From: "david knepper" <collinsradio at adelphia.net>
> To: <amradio at mailman.qth.net>; <boatanchors at mailman.qth.net>
> Sent: Monday, January 09, 2006 3:50 PM
> Subject: [AMRadio] Millen High Voltage Connectors
>
>
> > My homebrew transmitter,  designed by Stan, W3TGR now a silent key,  is
> > going through exhaustive and often frustrating testing.  Stan
> used lots of
> > shielded wire - you know the Belden stuff that is deteriorating
> over time
> > with brittle insulation on the wire. I had to replace several leads
> because
> > the center conductor was shorting to ground when the insulation became
> > brittle.  So it goes ...
> >
> > Today, I thought that I had finally debugged the unit - pair of 813's
> > modulated by 805's - but I heard the troubling sound of high voltage to
> > ground.  Measuring the Millen connectors to ground revealed a
> short.  Here
> > the Millen connectors on the modulator were arcing to ground on the
> > secondary side of the modulation transformer running from the
> high voltage
> > through the secondary winding to the PA amplifier.   I am using those
> light
> > tan units that are supposed to be better than the red connectors.  Stan
> used
> > these connectors on the PA amplifier, the modulator deck, and the high
> > voltage power supply.
> >
> > I suppose that under modulation that the peaks exceeded the
> voltage rating
> > of the Millen connectors.  Once before many years ago, I had the same
> > problem.  However, these connectors are often used in homebrew
> construction
> > projects as described in the ARRL handbook.
> >
> > Any ideas out there other than to go with ceramic feedthrough
> insulators.
> >
> > Perhaps, it is because of their age and the insulation is breaking down.
> > Who knows!
> >
> > Thanks
> >
> > Dave, W3ST
> > Publisher of the Collins Journal
> > Secretary to the Collins Radio Association
> > www.collinsra.com - the CRA Website
> > Now with PayPal
> > CRA Nets: 3805 Khz every Monday at 8 PM EST
> > and 14255 every Saturday at 12 Noon EST
> >
> >
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