HV Cable DS2124

[Rex Allers]

Looking at a catalog from an HV supply manufacturer, they seem to change output cables from RG-8 to DS2124 at about 75 or more KV.

I did a search here for 2124 but didn't find any hits. I found one link in my web searches on the mfg site with a some info about DS2124. Seems DS = Dielectric Sciences. Wondering if the knowledgeable here have any thoughts about 75 KV up. Does RG-8 stop being safe?

Anyone have experience with DS2124? My guess is it is difficult to find and expensive. Any alternatives or advice for what works in the obtanium realm and isn't hazardous?

[Richard Hull]

Common 20-30kv rated, high voltage anode wire can be snagged from old color TV sets, but it is rarely more than 12-18 inches in length once clipped off the flyback and anode cup. This wire might still be found from local or large electronic distributors.

Once you hit 40 kv, common industry standard HV wire is a specialty item. Silicone "noodle" wire to 80kv is found but extremely expensive and un-shielded. The preference and "good practice" cabling above 60kv is always shielded and always rare and always very, very expensive. Industry standard connectors for voltages at this level are exceedingly expensive. A cable of 12 feet in length with proper NEMA rated plugs for 80kv would easily cost $600.00.

I have used hamfests and other surplus sources for years to obtain HV wire up to 125kv rating for just a few bucks per foot. Yes, you have to luck onto the purchase.....Yes, you have to know what you are looking at to see and recognize it. The moment you want to single source the stuff and demand specifics from a dealer you are looking at many dollars a running foot and steep minimum orders.

RG-8 is a common RF cable and is often pressed into service as a high voltage DC cable, but it is struggling against high tension breakover at 40kv....You could push it, I suppose. Here is what Spellman has to say about RG-8U cable use, or mis-use, in their AN-07 tech blurb.........

....."RG8-U has long been used as a high voltage output cable in the high voltage industry. There is a variation of RG8-U that utilizes a solid polyethylene core. Specifications for this cable do not specify actual "high voltage" ratings, since this cable was not designed and fabricated with high voltage usage in mind. So the reality is, there are no high voltage ratings for RG8-U. Over the years others in the HV industry have used this cable at 20kV, 30kV and even higher voltages. Spellman does use RG8-U cable, but limits it usage to applications where the maximum voltage that will be applied to the cable is 8kV or less.".....

You should not push this cable to extreme limits in fusor use. You need good cable rated for your voltage used. I would imagine it would make a good demo fusor HV cable up to 20kv or so.

As an engineer I approached Dielectric Sciences in a phone call this morning and asked for pricing on their # 2121 cable and was surprised at the relatively low price per foot of $7.00 for this 100kvdc rated cable!.... SNAG!!!.... If you are not ready to buy 50 feet as a very minimum basic order, please don't call us again! So... $350.00 plus shipping and you have your cable. Certainly, more than you need. This is not being nasty, It is an industry norm and serves to keep out the Tiny Tim players.

Get out and go to hamfests and surplus stores. E-bay even has the stuff on occasion.

Last year, I saw a 20 foot length of the nastiest cable I have ever seen laying on the ground at a hamfest. The key was it was a filthy gray color with oil and dirt caked all over it and was one inch in diamter. I picked up one end and saw a filthy white silcone interior with about an 18 gauge central, stranded conductor core and a braided shield in a doubled outer layer. I knew immediately what it was. I asked, " how much for the dirty cable"? The guy noted there was a lot of copper in it. I told him that I doubted if there was much more than two pounds in it. He called out $10.00 and I handed it over. I got very dirty just carrying the big heavy cable back to my car. Fortunately, I had a roll of paper towels in the trunk. Thirty or forty paper towels later the wire was mostly grime free and just barely clean enough to put in my trunk.

Once home, another 30 minutes or so with bathroom tub and tile spray cleaner and some WD-40 revealed the cable was a beautiful battleship gray with markings reading 100kv - X-ray cable on its jacket. While few people on the earth's surface can use or even need this cable, I got it for about 1/50th its new cost. It is coiled up in my lab awaiting fusor V construction with my 85 kv supply.

Don't bypass filth, oil and nastiness..... Search... Investigate... Be able to "see at sight" and you will save, big time.

Note* I have used this as a basis for a new FAQ on HV wire.


Richard Hull

[Rex Allers]

Thanks, Richard. Just the sort of info I was looking for. Good to know it will be a FAQ.

[Garett Goodale]

This is off topic, but I was curious if anyone knows what wire is used in particle accelerators that have multipliers that can reach voltages of 1mv. Or do they just use corona shielded wire and make sure it is a few feet from everything?

[John Futter]

Garett
they do not use Wire. The multipliers are under insulating gas usually SF6 @ 50 PSI, sometimes a mix of CO2 and N2 @ 350PSI and the terminal is under the same gas insulator

[Richard Hull]

Corona and wire issues abound in power supplies in air at about 100kv. Few mains power supplies exist in air above 150kv....That is, ones that can handle significant fusor currents. Virtually nothing is gained by going above this level in D-D fusion as the cross sectional curve starts to flatten out. The biggest gains are 10-100kv. I know of no successful amateur in the 100kv range. Most are 50kv or less.

Richard Hull