|[AMRadio] Millen High Voltage Connectors|
Brett.gazdzinski at mci.com
Mon Jan 9 18:55:57 EST 2006
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
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
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
~73~ Eddy VE3CUI - VE3XZ
PS: Emphasis on the words "...good-quality" --- NONE OF THAT CHINESE JUNK
----- 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
> 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
> tan units that are supposed to be better than the red connectors. Stan
> 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
> 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!
> Dave, W3ST
> Publisher of the Collins Journal
> Secretary to the Collins Radio Association
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