Need HV connector for Spellman XLF

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Paul W Fontana
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Need HV connector for Spellman XLF

Post by Paul W Fontana »

I need a HV cable for a Spellman XLF HV supply I bought on eBay some weeks ago and got around to trying out today. There are, strangely, two model numbers shown: either XLF40N600X2559 (apparently the original) or XLF30N600X2274 (on a sticker; see photo), so I don't know if it's -40kV or -30kV for sure. I jumpered the interlocks and remote control terminals according to the manual and turned it on and it appears to be working. At full voltage the front panel meter reads -41.7 kV. I don't have a probe that can reach deeply enough into the connector socket to reach the terminal, so with no cable I have not been able to check the output directly.

I remember reading that these things usually take Federal Standard connectors, but I'm puzzled because I only see one terminal in the depths of the socket (see photo) and have been unable to find Federal Standard connectors with only one pole. The manual also shows a three-terminal connector. I tried taking it apart to get a closer look, but the business part of the internals is enclosed in a tightly sealed and packed-in metal box that looked like it didn't really want to be opened without a bit of struggle. The insulating socket has a i.d. of 17 mm and a depth of about 12.3 cm. I have some HV cable on hand, including some 50 kV-rated red-insulated stuff with an insulation o.d. of 1.0 cm and conductor o.d. of about 1.3 mm, as well as a fair amount of RG-8/U. I just need to figure out a way to make a sound connection to the supply.

I recall reading on here some suggestions about lining a socket with grease, placing the cable, and filling the socket with epoxy, but don't want to risk that without some more detailed instruction at the least. I have a call in to Dielectric Sciences and they're going to work up a quote, but I have a feeling it's going to be in the multiple $100's. If anyone has any idea how to get a hold of the right connector or other suggestions on how to connect up my line I'd be grateful!
Attachments
Duo model number labels
Duo model number labels
Inner Sanctum of the power supply
Inner Sanctum of the power supply
Socket
Socket
Depths of the socket, showing one contact point
Depths of the socket, showing one contact point
Rex Allers
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Re: Need HV connector for Spellman XLF

Post by Rex Allers »

I'm no expert, especially on Spellman since I only have Glassman supplies. This stuff has been discussed before but in a quick search I didn't find exactly what I think I remember in the best posts.

For the Glassman supplies I have made my own supply-end HV connectors by drilling out a PL-259 connector and putting it on appropriately prepared RG8 coax cable. On the Glassman I carefully measured a reasonable length inside the connector tube with a wood dowel. Inside of the supply, the connector is spring loaded. On my cable connector I soldered a brass washer on the end as a connector.

Since I haven't seen a Spellman supply, I'm not sure if the outside ground connector is also compatible with a PL-259 or something else. From posts here I gather that the inside connector for the Spellman plug is something like a banana plug. I'm not sure if the socket inside the HV connector on the Spellman is fixed or spring loaded. My guess is fixed.

So if you can find or make the right parts you can probably make your own plug out of RG8 cable. Others here have done it -- maybe you will get better replies from others.

RG8 isn't rated for HV at fusor levels but I think many here have used RG8 (with solid poly dielectric) up to about 50 KV.

If you search for all the posts by "Cliff S" you will have the "word of god". He is "the man" at Spellman and has replied here in the past. On this forum in "Advanced Search"
you can specify "Search for author" to find all his posts.

Until you get better answers, here are a few forum links I saved that might be a start...

Glassman Cable
viewtopic.php?f=11&t=10035&p=67321

HV Cable
viewtopic.php?f=11&t=9114&p=62123

RG8 as HV cable
viewtopic.php?f=11&t=4900&p=32072#p32072

--- Edit ----
Looking at the outside connector on your HV supply, it doesn't look like this one is compatible with the threads of a PL-259 plug. There is no mating sawtooth like a PL-259 and to me it looks bigger and has a key slot.

I'm pretty sure on the Glassman supplies that the depth into the socket (and hence the proper plug length) increases with voltage, so a random ebay purchase that looks right, may or may not be. (Just a caution for shopping.)
Rex Allers
John Futter
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Re: Need HV connector for Spellman XLF

Post by John Futter »

Rex
older Spellmans use a banana plug centre connector on the end of RG8 or similar coax
the inner of the coax goes into the unit and the banana plug inner goes into a socket there
careful probing will tell you the depth of the socket you make the striped coax this length and put the banana inner on the end after cutting back the inner insulation to allow the copper conductor to reach into the banana plug
some resistance to doing up the connector is good ie its feels slightly too long on the coax inner if too much shorten it a little bit
the connector outer looks like a canon or amphenal connector

use your newark element14, RS components catalog to get the right outer socket

this will require modification

Cliff might join in with more info
Cliff S
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Re: Need HV connector for Spellman XLF

Post by Cliff S »

This unit (both X#’s referenced) use a connector designed to mate with a Trufocus X-Ray tube. The connector is a Trufocus design, their PN SK1-1-94. The cable is usually attached to the X-Ray tube housing. I doubt you will be able to find the mate. I also doubt Trufocus would be willing to sell just the cable/plug, unterminated on the other end. (If they would, I imagine it would be a small fortune).

The internals of the connector are shown on the attached pdf’s. There are two contacts at HV: One for filament, the other the HV ref/output. You can short them together with no impact. (Filament driver likes to run into a short, rather than an open). If you are brave, you can try to rig up something to make contact at the HV end. The connector is long enough to support 40kV without grease. But if in doubt, some clean grease won’t hurt. The ground end is an Amphenol shell PN 97-181-24. Getting just the mating shell for that will also be an endeavor. A clip lead on the shield of the HV cable might suffice. (Keep it short).

RG8 for 40kV: If the voltage modulation/cycles are kept low, you have a reasonably good chance at it working fine. It is not something that we use for high reliability though.

Labels: No clue as to why there are different labels. One is the original label, (X2559), the other is a service label (X2274). The HV multiplier inside is a 40kV PN, and if you are reading 40kV on the front panel, good chance it’s the 40kV X#. Both labels have date codes on 1996…20 year old unit.

Be safe. Its dangerous.



Best Regards,
Cliff Scapellati
Executive Vice President of Engineering
Spellman High Voltage Electronics
631-630-3110
Attachments
303433-001 Model (1).pdf
(39.56 KiB) Downloaded 558 times
303435-001 Model (1).pdf
(69.17 KiB) Downloaded 559 times
202046-001 Model (1).pdf
(65.96 KiB) Downloaded 584 times
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Richard Hull
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Re: Need HV connector for Spellman XLF

Post by Richard Hull »

Once again, Cliff to the rescue! Thanks for hanging in there with us Cliff. Most folks here are not familiar with the standards demanded for safe,
plug-in HV cables. We naturally mean really high, high volatege cables! Fusion really is not detectable at an advanced amateur level much below 20kv, but gets much easier above 30kv. To sell a product that is plugable in the 30kv range, a custom or special plug and cable is the normal solution.

Many arriving here find out about the above fact the hard way. But, those that pack the gear needed to carry out fusion will figure out a way around such issues providing they have a modicum of tech savvy and respect the voltages they are attempting to use.

Your suggestions on possible work arounds and freely given diagrams, PDFs, etc., really do help smooth over the bumps for many. Again all your efforts are, and will continue to be, greatly appreciated.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Paul W Fontana
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Re: Need HV connector for Spellman XLF

Post by Paul W Fontana »

Yes, thanks indeed, CliffS! That's immensely helpful! I've made an inquiry at Trufocus. The technician I spoke with said it didn't look like part number of theirs (perhaps obsolete since 20 yrs old), but I gave him the specs and he's looking into it.

Meanwhile I discovered that a 1/4" rod fits well into the contact at the back of the socket. (It wasn't clear to me from the drawings or my visual inspection whether the contact was M or F, but now I know!) I insulated the rod temporarily with multiple layers of tygon tubing and was able to get the supply up to 39kV on the panel with a little headroom left while measuring with my Electrotec HV probe. Above that the tubing failed and the supply arced, but seemed to recover with no trouble. (I know it's not designed for that stress and so won't push it again, but it was nice to see it shrug it off.) The probe agreed with the meter until the voltage got above about 30 kV, after which the probe registered slightly higher, up to about 42 kV when the meter said 39. Separately, I found that a 5/8" dowel was a loose fit in the socket and a 3/4" wouldn't go in, as I expected from my measurements and the drawings. So if Trufocus doesn't come through or is too pricey, it looks like I have enough information to make something out of Delrin tube, a 1/4" diam. copper or steel tip, and a central wire made of RG-8/U core or my 50kV HV cable, then probably filled with epoxy between the wire and the tube. Let me know if any of that sounds dangerous or unlikely to work.

Thanks, all, for your input!
Cliff S
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Re: Need HV connector for Spellman XLF

Post by Cliff S »

Hi Paul,
Just to clarify the original design: It used a "banana" plug internal to the receptacle in the XLF. That can be seen in the drawing detail of the internal collar part. It may have broken off or become unscrewed...???
The diameter of the threads for the banana plug would be much less than 1/4". So maybe you are bumping up against the tip of the banana...???

Or, maybe I am not fully understanding what you are describing. (Send a pic).

I would imagine a Lexan, PE, Delrin tube, (not a rod), with the appropriate ID to accept RG8 bare cable (or whatever you use) and OD to go all the way into the end connection collar, and some simple copper tape wrapped around the last cm or so, folding back inward, and then terminating to the HV lead further in, allowing for the banana to insert into the ID...(breath)...might work. Or, just solder a metal tube onto the end of the RG8 that would accept the banana plug......with shield stripped all the way back of course.

Best Regards,
Cliff
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Richard Hull
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Re: Need HV connector for Spellman XLF

Post by Richard Hull »

I had 4 old Spellmans here. I found them at a local scrap yard for $5.00 each. All meter glasses smashed out, but movements good. I replaced the glass in one (the least bunged up) and sold the other three at old TCBOR/HEAS events.

All had the same issue. One of more of the wad of 2N3055's Spellman put in them were blown. Luckily I had a bag of 20 of those bought at a hamfest on hand. (all of this was back in the late 90's)

I made up my cable out of plexiglass tubing running 40kv silicone, copper core, racing auto ignition wire through them with a bannana plug connected and epoxied into the tubing's hot end. Simple, easy and cheap. I just didn't worry about the metal case threaded end at all, allowing the plexiglass (lucite) tube to extend out the back about 3 inches and let the silicone wire rated at 40kv do the rest once outside the rig.

The supplies were weak (only 2 ma), but I use mine, to this day, for a lot of static electricity motor demos, charging caps for water arc cannons, thin wire exploders, etc. Spellman makes good stuff.

Sure, I could do all that with a home built flyback rig, but having a metered Spellman, you can build and test for lower starting voltages on static motors at much lower run currents...... Plus, they were cheap and are, in effect, a nice metered HV lab in a box.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Paul W Fontana
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Re: Need HV connector for Spellman XLF

Post by Paul W Fontana »

Cliff S wrote:Just to clarify the original design: It used a "banana" plug internal to the receptacle in the XLF. That can be seen in the drawing detail of the internal collar part.
Yes, I saw that and was a bit confused. Then I realized what I was calling a "rod" was actually a tube with a 0.15" i.d., and the friction I felt as I inserted it was the tube slipping over the banana plug rather than slipping into a 1/4" socket.

I was imagining something in between your two suggestions: a Delrin tube with some copper tubing glued in the end and sticking out 0.6" or so, with the stripped RG-8 or 50 kV wire soldered to the copper tube and running down the inside of the Delrin tube. If I got 1/2" i.d. and 5/8" o.d. Delrin, the 50 kV wire will fit fairly well but the RG-8 would leave some room - maybe some epoxy at each end would be enough for mechanical strength. The Delrin would be slightly loose in the socket. I could either live with that, or wrap it with something - easier than getting 3/4" o.d. and turning it down. Starting to sound pretty simple after all!

-- pwf
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Rich Feldman
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Re: Need HV connector for Spellman XLF

Post by Rich Feldman »

Paul W Fontana wrote:...Then I realized what I was calling a "rod" was actually a tube with a 0.15" i.d., and the friction I felt as I inserted it was the tube slipping over the banana plug rather than slipping into a 1/4" socket.
Yay for banana plugs and thin straight metal tubing! Their engagement was mentioned here less than a year ago. Scott Moroch had a Glassman PS, which arrived with a cable that had a banana plug on center conductor. John Futter said the cable probably went with a different PS. Anyway...
viewtopic.php?f=11&t=10035&p=67332#p67332
All models are wrong; some models are useful. -- George Box
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Paul W Fontana
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Re: Need HV connector for Spellman XLF

Post by Paul W Fontana »

Here's what I came up with. 1/4" o.d. copper tubing for the tip, soldered to conductor of 50kV-insulated wire, inserted through 5/8" o.d. x 1/2" i.d. Delrin tube long enough to stick out of the socket about 3-1/2", tip epoxied to the end with (2) 1/4 sae washers for centering and mechanical support. Then four layers of electrical tape at the front and back ends to make a snug fit in the socket (and a little more epoxy because it wasn't quite as strong as I wanted it). I'm liking this copper-tube-to-banana-plug system so well that I think I will use it for my other HV connections as well - simple, inexpensive, and works great. I already put a banana plug at the other end of this cable.

After testing I regret using the eBay 50kV cable rather than the RG-8. There's no shield, and the insulation crackled with a little corona at voltages above about 35 kV when probed with my grounding stick. I'll wrap some grounded wire around it for safety.

-- pwf
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homemade Spellman XLF HV connector.jpg
homemade Spellman XLF cable tip.jpg
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