BNC cables, terminators, Tees, etc.

[DaveC]

Ummm... sorry about that little bit of non-sequitur there on MPJones.

Re: these HVPS connectors. Bertran , Glassman, Spellman and Kaiser... to name the common HV supply mfrs... tend to go to a modified UHF type connector... and use RG8U solid PE insulated cable. It works well even up to 75 -80 kV, ....provided you have a long enough creepage path in the inside. Most of supplies will press a snug fitting PE or even PVC tube whose ID just accomodates the RG8 through the connector shell and that takes care of the feed through.

I have quite successfully made connectors for use up to 80 kV this way... and it works well. Usually, the threaded barrel, UHF bulkhead socket is preferred since you can't casually remove it, accidentally.
You can get these fittings from the local electronics store, (sometimes) ... not Radio Shack. Also Amphenol and AMP are the common brands for the UHF fittings. Newark Electronics, Digi-Key, and Pasternack are good (not cheap) sources.

All that one needs for these medium HV (1kV - 10V) connectors is a smooth ground plane where you transition from the cable shield to the bulkhead, and an inch or more for a few kV behind the panel in the plastic sleeve. I use a banana plug end for the actual HV connection and it works fine.

For perspective, at 80 kV, the sleeve has to be a minimum of 8 inches long behind the panel in order to prevent flashover. It is not a linear relationship between KV and creepage distance, but you can get the flavor. For a couple kv, you would need only about 1 inch.


Dave Cooper

[Tom Dressel]

I found the connector on Bertan's web site, It's a Kings SVH connector #1064-1 sold by Allied Electronics that mates with a Kings #1065-1.

Tom Dressel

[guest]

Funy you should mention that Kings part #. I think it's a 10kV style SHV that is also used on one of my compendium ion pump supplies. I'm surprised to find that Allied stocks them . Duniway wants about $50 apiece for these connectors. I hope Allied is a little better.

[guest]

A note on the availability of the Kings 10kV SHV connectors - the only one of King's distributors that seem to have them are Arrow electronics, who list the 1065-1 plug at 30-odd dollars and the 1064-1 jack at around 45 dollars. High voltage, like vacuum, is an expensive proposition.

[Tom Dressel]

What ever the price for the connector, I am sure that it is not as obscene as what Bertan gets for the connector and 6 feet of cable.

I have the Kings spec sheet on the 1065-1 plug. It states that it is for use with a RG-58 cable. Isn't 10 Kv pushing the limit on RG-58 cable?

This forum is great, nowhere else can I get help drilling down to the most arcane detail of fusor construction, like a part number for some oddball connector.

Tom Dressel

[guest]

RG58 is supposedly good for around 1700 0r 1900 or so. This is good for PMTs, but I don't know if I would trust it with 5000V.

[Tom Dressel]

I called Bertan today, they want $80.00 for the Kings connector swaged to 3 Meters of RG-58U cable. So the question is, do I go for the ready made cable or take a chance on crimping my own for about 1/2 the price?

Tom Dressel

[guest]

If it's a connector on each end, that's not too bad a deal - If it's one connector, I wouldn't bother. The 1065-1 connector takes a standard-looking hex crimp. You can buy a pretty decent looking tool at Radio Shack to do a hex crimp for about $15. This will come in handy later. I would ask the folks at Kings about the recomended stripping lengths.
It appears that folks get away with murder in overvolting coaxial cable. RG58 is rated at 1900VRMS, and RG8 is rated at 5,000 VRMS, yet folks seem to get away with running these cables at much higher voltages. I would be sure and get a good grade of cable if you plan to do it yourself.

[Tom Dressel]

Thats an unterminated cable, with the 1065-1 connector on ONE end. If the hex crimper is the same one used on coaxial TV cable then I have one.

Tom Dressel

[Richard Hull]

I have used RG-8 to 25 kvdc with no problems. Remember, Coax is rated for RF signals. It was never created with DC in mind. Therefore, the smooth, static, non-pulsed DC ratings are very high compared with RF ratings which stress the dielectric severly by working it to death. This is especially bad with pulsed RF.

Most of the problems occur with RG-58 and other cables in connecting the stuff at each end and avoiding electrostatic corona leakage and attendant arc-over problems. This is why the MHV and SHV BNC connectors were designed. They are so good and so expensive because of the longer metalo/dielectric interfaces which take a lot of turns to help avoid the classic dielectric-coronal flashover so often seen on flat surfaces. DC power coax needs no termination, of course.

Richard Hull

[Tom Dressel]

I talked again to the sales depertment at Bertan again today, reguarding the power supply cables. As stated previously, the weak link in the system is the standard BNC connector not the RG-58 cable. The RG-58 cable is tested by Bertan to 12 KV DC. The Kings 1064-1 "10 KV" connector is tested to 15 KV DC. So if you are going to run the cable and connector over ~500 volts, it should be terminated with a MHV or preferably a SHV connector, again this is due to the creep path limitations of the BNC connectors.

Tom Dressel