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ashart
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« on: April 03, 2017, 02:40:16 PM » |
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Good day ol' timers! I've read that the brown mica version (37501) of the Millen HV connectors is rated at a higher voltage than the red or black versions. However, my old Millen catalog merely states that the mica versions are "low loss." I'm used to the term "low loss" relating to RF leakage issues, not with voltage-withstand issues. Any wisdom available on the seeming contradiction? Thank you. -al hart al@w8vr.orgwww.w8vr.org |
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W1ITT
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« Reply #1 on: April 03, 2017, 03:03:27 PM » |
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Those Millen HV connectors have always scared me just a bit. I prefer a connector that does a better job of protecting the HV, and preferably carries a safety ground with it. Not that I don't have a couple on pieces of gear around here, and I'm careful enough to have been licensed for 50 years without getting much more than a tickle, but they are a "caution".
Recently, I have been using HN connectors for the kilovolts, and UHFs to carry the B-minus, and they both carry a ground separately. Surplus Sales of Nebraska occasionally has some nifty looking HV connectors as an alternative, but they are pretty pricey. (Yeah, I know, how much is my life worth, or how bad would I feel if my tomcat got behind the amplifier and got mixed up in something that he shouldn't?)
But to answer your question... I dunno.
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WA5VGO
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« Reply #2 on: April 03, 2017, 07:05:24 PM » |
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They're all rated 7KV DC.
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WD5JKO
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WD5JKO
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« Reply #3 on: April 03, 2017, 09:27:18 PM » |
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This was a topic last year at a "Real Radio Breakfast". Jack K5LRX was a walking encyclopedia on the topic. I wish I remembered what he said. Surplus Sales of Nebraska has 4 color options. The yellow is High Voltage "RF". http://www.surplussales.com/wire-cable/hvwire-2.htmlJim Wd5JKO |
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KL7OF
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« Reply #4 on: April 04, 2017, 09:13:40 AM » |
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I have noticed that those HV connectors don't seem to age well......They get brittle and hard...they can crack...
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W3RSW
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Rick & "Roosevelt"
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« Reply #5 on: April 04, 2017, 09:15:00 AM » |
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Tnx !
Neat stuff including Harris' Jesus stick and a shorting pin switch, complete with YouTube movie showing travel distance of pin.
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RICK *W3RSW*
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ashart
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« Reply #6 on: April 04, 2017, 01:55:21 PM » |
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WA5VGO
Thank you. Can you cite any authority for your statement?
73.
-al hart
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w4bfs
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more inpoot often yields more outpoot
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« Reply #8 on: April 04, 2017, 05:34:29 PM » |
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I believe these connectors are molded bakelite with some having mica fill...
bakelite has poor impact resistance (tends to crack somewhat easily) ...
I have seen these with a heat shrink tubing 'collar' around the knob ends to cushion/hold together...
seems to work ...
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Beefus
O would some power the gift give us
to see ourselves as others see us.
It would from many blunders free us. Robert Burns
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W3RSW
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Rick & "Roosevelt"
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« Reply #9 on: April 13, 2017, 04:54:55 PM » |
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I wonder if dipping (carefully, no contact with metal) into super glue would impregnate the hairline cracks for a permanent bond?
Funny story. You'd have to establish that the combination wouldn't be conductive. Think I already told this story, but..
When I worked for Birdwell div. of SSC/Raytheon many years ago in downhole well logging at Nevada test site, we sprayed a lateral electric logging tool with detergent to clean it up.
Couldn't get a reading for calibration right off the bat. After hour of frustration decided to measure resistances across the contact shoes and voila, the crap was conductive, not zero, but way more than any semblance of high resistance.
LRL was not amused. I think they called in Schlumberger after releasing us.
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RICK *W3RSW*
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KA2DZT
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« Reply #10 on: April 13, 2017, 08:32:26 PM » |
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Use varnish to fill in any cracks. I have a bunch of those connectors here. They look like an accident waiting to happen.
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KD6VXI
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« Reply #11 on: April 14, 2017, 09:21:07 AM » |
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I won't use them.
--Shane
KD6VXI
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Jim, W5JO
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« Reply #12 on: April 14, 2017, 03:57:59 PM » |
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I won't use them.
--Shane
KD6VXI
I won't either if the voltage is over 3.5 KV. I allow a 2 times factor with voltage over 1KV. Below that they work fine and if there are cracks chances are they have been bumped or over tightened. They were used on the GK 500 series and those on my 1954 GK 500A are just fine. |
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KD6VXI
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« Reply #13 on: April 14, 2017, 08:09:44 PM » |
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Jim, W5JO
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« Reply #14 on: April 14, 2017, 09:42:52 PM » |
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If you want to be cheap Shane, then use spark plug wire rather than coax. It has higher insulation resistance and better bend radius. You should be able to get wire with metal conductor at your local auto parts store. It is used by racers so should be available. |
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KD6VXI
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« Reply #15 on: April 15, 2017, 10:20:01 AM » |
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I've used the spark plug wires for awhile. You can even slip braid and the outer skin of coass over it. Takes some of the bend radius out but also allows for shield and ground all in one.
Still have to have connectors. And don't use resistance wire!
Although resistance wire may work on my cheap side... Built in glitch r.. (just kidding lol).
--Shane
KD6VXI
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Detroit47
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« Reply #16 on: April 15, 2017, 10:37:59 AM » |
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W2PFY
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« Reply #17 on: April 16, 2017, 06:31:23 PM » |
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Nice connectors here and not costly! EVEN BETTER they have ready made spark gap modules that look great and I am sure they are designed for the average old buzzard class B modulator circuits. I ordered a few of those. BTW, it you're a builder or a dreamer, the sources that we get for free here can't be beat! |
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The secrecy of my job prevents me from knowing what I am doing.
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Detroit47
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« Reply #18 on: April 16, 2017, 10:21:23 PM » |
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I use Millen connectors up to 7KV, but I mount them to Glastic or Teflon. They have a nasty habit of arcing if any stray RF get on the HV line.
73 John N8QPC
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