another question.

[ka3zlr]

Hello Happy Holiday.


 On My 3500V B+ supply... I have to lengthen the feedline....I don't want to..but i have to....

 So i want to go with new Construction....Gooder connectors...Don't mind using conduit at all...etc...What should I use I have my own ideas But this is Hot and i have cats and dogs and kids here....Something very very Safe...

Appreciate any help..the run is 7 feet....


73
jack

[KM1H]

Well, 30kV wire inside Teflon tubing should be safe but its not bite proof

RG-213 ( no foam dielectrics or bargain brands) and all Amphenol Teflon connectors should be fine up to 5kV and of course it will be fused as well as have transient suppression....right?

Many years ago I remoted a 7200V supply in the basement and ran RG-17 to the next floor and used LC connectors. That was a very hard cable to manuever but I still see it and the connectors at times.

Carl
KM1H

[ka3zlr]

Hi Carl Thanks,

 I remoted the supply to casters so it's mobile now, and easily opened for service I didn't want to base load it in the cabinetry..be nice if I could come up with an idea for quick disconnects That would be optimum...but I'm not taking any chances with the cats nebben around here..they get into everything..

much obliged for the ideas.

[WA1GFZ]

I would use RG8 or RG 11. When you wire a weapon you put a shield over the bundle so if the cable gets pinched there is a short to ground. Fail Safe.

[KM1H]

I would use RG8 or RG 11. When you wire a weapon you put a shield over the bundle so if the cable gets pinched there is a short to ground. Fail Safe.

RG-8 and RG-11 are generic designators that no longer have mil-spec standards. Also sold under RG-8/11 type. Fine for most antenna work but I wouldnt trust any of it at HV unless I hi potted it first. And even then you have no idea about the jacket contaminating the dielectric over time.

When in doubt use Belden or another top quality brand.

The same can be said for PL-259 and SO-239's. There is a lot of garbage out there plus the often seen WW2 stuff probably has contaminated insulation by now.

Carl
KM1H

[WA1GFZ]

I never use PL259s =junk
I like HNs for HV
There is also a HV style BNC that can handle some real voltage but I've never been able to buy one. We have one on one of our lightning set ups. A normal BNC dies around 1 KV while the special one doesn't miss a beat.
Yup stay away form foam cable for HV. I've never flashed over RG8 or RG11 up to 6 KV or so. Then there is teflon RG393 or RG400 with the new mil names of course.

[Tom WA3KLR]

I have worked at a high voltage power supply company and surprisingly found that they were using RG-8 at up to 60 kV. for a long time now.  They feel quite confident in this, re-testing over many years.  Competitors use even higher voltages on the RG-8. 

As I recall the break-down is found to be greater than 80 kV.  The big factor here is dc versus radio frequencies; big difference in the insulation physics.

Obviously they don't use PL-259s or SO-239's.  They did use the outer metal threaded collar of a SO-239 for a chassis feed-thru but the center conductor connection is a home-brew design thing which is offset many inches inside the product from the chassis feed-thru.

They use RG-58 also but I don’t recall what HV they rate it up to.  You can look up the r.f. breakdown specifications for RG-8 and -58 and scale it for a ball-park number for RG-58:

RG-58 1900 V. r.m.s.
RG-8   5000 V. r.m.s.      1900/5000 X 60,000 V.dc. = 22,800 V.dc.

Round down to 15,000 V to be conservative.   Sounds about right for what they were doing with the RG-58, as I recall.  You’re on your own though!

[Opcom]

I always either enclose any HV wire or use coax. If you want to use some kind of metal sleeve or conduit, I have some 15KV outdoor rated 14 guage stranded neon sign transformer wire. A whole box of 250ft was $28 a few years ago if you need a few feet.

they sell it here by the foot:
http://www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=775

[KM1H]

I never use PL259s =junk
I like HNs for HV

There are good uns and bad uns. A good un will handle 3500VDC. I know several who have pushed them to 4500-5000V but I wouldnt try it.

Havent used HN at home, just in industry.

There is also a HV style BNC that can handle some real voltage but I've never been able to buy one. We have one on one of our lightning set ups. A normal BNC dies around 1 KV while the special one doesn't miss a beat.

Thats the MHV series. Rated 2KV at 50 mHz; I use at 2500V DC and audio. The last ones I got up at Deerfield were in a Kings package.

Yup stay away form foam cable for HV. I've never flashed over RG8 or RG11 up to 6 KV or so. Then there is teflon RG393 or RG400 with the new mil names of course.

I use RG 42B and 303 for RF inside of amps but never trusted it at HV due to cold flow. Its also a solid center conductor (silver plated Copperweld?) and hard to manuever.

As I recall the break-down is found to be greater than 80 kV.  The big factor here is dc versus radio frequencies; big difference in the insulation physics.

Thanks for that info Tom, I hadnt considered that factor BUT Im not about to find out either!!  After I left National Radio I worked for High Voltage Engineering for awhile. Built 100-250KV supplies that stood up to 7' tall for the textile industry. Scary stuff. I like my HV in 4 digit flavors.

Carl
KM1H

[Joe Long]

The numbers for the HV/BNC connectors are UG-931--+---UG-932

[WA1GFZ]

Tom,
I've seen the PL259 trick with high voltage. That is the only way I would use those hunks of crap. since you pass the dielectric and center conductor through the shell there is no air gap to flash over. Makes a nice termination to the shield with mechanical support.

[KA1ZGC]

A couple of points:

Either RG-8 or RG-11 will do the trick, but RG-8 is the better choice. RG-11 tends to have a single-strand center conductor that can be brittle. RG-8 center conductors tend to be stranded.

You also want to avoid foam dielectric if there are any bends in the cable run, or any chance of the cable being bumped against or stepped on. Solid dielectric won't distort or collapse the way foam will.

We ran solid-dielectric RG-11 for the B+ lead of the Harris FM-25K we just installed. The center conductor is a bit fragile, but it's run through conduit between the cabinets so it should be okay. I beleive Harris shipped it with RG-213 for that lead, 25 years and several owners ago. We're only going to run around 6500V, so there shouldn't be any problems with RG-11.

Newer HV connectors are actually getting to be cheaper than Millen connectors if you're buying new, beleive it or not.

--Thom
Kilovolts Attack One Zorched Ground Conductor

[WA1GFZ]

Millen connectors are also junk

[W3SLK]

Frank said:

Millen connectors are also junk

I've heard a lot of people say that but I have a number of them on my HN-500 and they have yet to cause any problems. Now I'm only runniing 2.5K VDC at the highest. I don't like the idea of using PL-259/SO-239's as HV connectors. Too much of a likelyhood of connecting the wrong device to the wrong place. I know they're expensive but SHV(?) connectors or ones just for HV modes is the correct choice.

[WA1GFZ]

Mike too much safety training. It is junk if it isn't shielded with metal to be fail safe. The Pl259/SO239 with the guts punched out is a great cheap high voltage connector High voltage should not leave an enclosure if it isn't shielded with a ground around it. Say you run packard 440 and your buddy stops by and sets a metal chair on the cable. Would you rather pinch the metal chair to the shield or B+.