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BNC cables, terminators, Tees, etc.

Posted: Wed Aug 22, 2001 4:47 pm
by Richard Hull
Marlin P. Jone and Assoc, Inc at

http://www.mpja.com

has a good selection of BNC cables, connectors, adapters and terminators.

On page 35 of their current catalog, they have a BNC 50 ohm professional terminator for $2.49, a BNC f-m-f tee for $2.25 and twist on male connectors for $1.50.

They also have other electronic goodies I have used.

They offer a nice sized, bright, LED digital panel meter (part # 12308-ME $12.95 each) which reads in volts (200 millivolts), but can be scaled to read any voltage. I used two of these in my fusor III set up to monitor current and voltge from my converted X-ray supply. (see my web page)

For those rolling their own counters, etc., they have a nice LED three digit counter kit (999 counts) which can be used in any cobbled up counter system. (part # 6001-KT $15.86)

I also am working up a vacuum system control built around their 12 bit data acquisition system. This boasts 4 ditigal bit inputs, four digital bit outputs. and (8) 12 bit multiplexed, A-D converter inputs. This is also a kit with complete software included (8418-KT $55.00)

This should help some of you hardware types out a bit.

Richard Hull

Re: BNC cables, terminators, Tees, etc.

Posted: Thu Aug 23, 2001 1:26 am
by Tom Dressel
Richard

Whot did you call those special high voltage BNC like connectors? I remember you said that they are expensive and never found on the surplus market. But I cant find your post on the connectors. It may have been on an IDJ post that was deleted.

Where can I find the connectors an the high voltage cable?

Tom Dressel

Re: BNC cables, terminators, Tees, etc.

Posted: Thu Aug 23, 2001 2:12 pm
by guest
The connectors are two types. MHV BNC and SHV BNC Most NIM stuff I have seen goes straight for the SHV BNC on supplies and the like. However, most geiger counters and portable apps go for the MHV BNC.

Larger Neutron counter tubes and the like use an even wierder and more expensive HV connector, the HN connector, with cables here costing over $100.00 in some situations.

All these connectors use standard HDPE insulated RG-58 cable which can withstand the tension.

There is no hard and fast rule, but most gear with voltages under 500 volts can use the BNC and those up to 1000 or even 1500 volts use the MHV. Above 1500 volts and up to 5000 volts, the SHV is used.

On personally designed stuff I have shipped 1200 volts through common BNC connectors and have routinely removed MHV plugs from geiger counters and ratemeters, replacing them with teflon insulated common BNC jacks.

The only real supplier I have seen for these bizarre BNC connectors and cables is Pasternack Enterprises

http://www.pasternack.com

Hold on to your wallets guys!!

A 3 foot long SHV male plug to male plug cable is $66.68!!
The MHV cable of the same type and same length is a steal at $33.68

Where is radio shack???

The raw SHV crimp plug is $20.95 each!! DO NOT SCREW UP YOUR ONE SHOT AT THE CRIMP!!!

Smart money flys BNC all the way provided you don't need over 1500 volts.

A very wise first buy is an adapter!!

For most NIM stuff this is pasternack #PE9265 ($64.95) this is a SHV plug to MHV jack.... you are now down to using the $33.68 cable. Into this you might even plug their # PE9297 ($23.95) adapter which is a MHV plug to BNC female jack. Now you are using $3.00 BNC cables. So for only $90.00 you can avoid buying a $66.00 cable. Actually it is better than this, for with the adapters, you can plug BNC cables into any oddball SHV or MHV situation you encounter, pretty much.

If you run into an MHV jack, just stick in the second adapter mentioned above and go BNC from there. If you slam into an SHV jack, just couple both adapters above together and use common BNC cables. This will not fly well with the neutron counter tubes (He3 or BF3) as they often need 2300 volts on them. DO NOT USE BNC CABLES HERE!

Most of the stupid SHV BNCs are encountered on NIM bias supplies which can go to 5kv max. If you are only going to 800 volts for a geiger tube or 1000 volts for a PMT, then use adapters and a BNC cable!

The other solution is to alter the item itself by removing the SHV connector and installing a MHV bulkhead connector in its place #PE 4193 ($10.95) and then adapt with the cheap adapter to BNC. Most all MHV type gear, (geiger counters and the like), can be down graded to regular BNC bulk head connectors # PE4010 ($4.95).

Another rule of thumb is you can carefully down grade one connector notch in a controlled, moisture free, clean environment. The exception is if you are using a 5000 volt variable supply which demands and uses an SHV connector but you only need to get 800-1000 volts, then feel free to adapt down to BNC cabling. I would never alter the original connector here though as it is required if the instrument is to be used in future for voltages over 2kv.

No matter how you cut it, MHV and SHV cabling is almost a federal government purchase item. Even for we poor experimenters, the adapters to use affordable cabling are a near $100.00 hit in the wallet.

Richard Hull

Re: BNC cables, terminators, Tees, etc.

Posted: Thu Aug 23, 2001 2:42 pm
by r_c_edgar
Richard - there was a minor typo in the link you placed in the above post, so it went to a completely unrelated site, instead of Pasternack Enterprises.

I went ahead and fixed it to point to the correct address.

-Ryan Edgar

Re: BNC cables, terminators, Tees, etc.

Posted: Thu Aug 23, 2001 4:42 pm
by Tom Dressel
Can you tell what kind of connector it is by looking at them?

The upper left, upper right and middle left are Standard BNC connectors.

The lower left connector is on the input of the high voltage "passthrough" on a proportional counter preamp and is listed as a SHV BNC.

The question is what is the connector on the lower right? It is on the output of a Bertan 0-10 KV power supply. Is it a MHV BNC or the moer exotic (expensive), HN connector?

Tom Dressel

Re: BNC cables, terminators, Tees, etc.

Posted: Thu Aug 23, 2001 11:38 pm
by guest
The high voltage input connector is an SHV. These are commonly what you will see on a lot of the newer equipment, as they cannot be mixed up with ordinary BNCs. Alas, they are harder to get than MHV connectors, which are the other high voltage BNC type. Hamfests and or surplus is one route (slow but cheap). If you are in a hurry, try someone like Digikey (expensive) or Pasternak Enterprises (merely outrageous rather than rape-and-pillage).

Re: BNC cables, terminators, Tees, etc.

Posted: Fri Aug 24, 2001 10:59 am
by Tom Dressel
Yes, the high voltage input connecter is an SHV. But what is the high voltage connector, lower right, on the OUTPUT of the High voltage power supply?

Tom Dressel

Re: BNC cables, terminators, Tees, etc.

Posted: Fri Aug 24, 2001 1:16 pm
by guest
Can you post a more oblique view of the HV connector? It looks longer than the standard BNC. If it is, it may be a 10kV class MHV, but I'm not sure at this point.

Re: BNC cables, terminators, Tees, etc.

Posted: Fri Aug 24, 2001 4:10 pm
by Tom Dressel
Here is the oblique view of the 10 Kv output. Anyone know what kind of jack it is and what kind of cable it takes?

Tom Dressel

Re: BNC cables, terminators, Tees, etc.

Posted: Fri Aug 24, 2001 8:30 pm
by DaveC
I have seen MPJ 's stuff and they have some excellent prices. I have found that the local big electronics store matches their prices...on most hardware...they probably all get it at the same places.

They MPJ also have a good selection of mini-video cameras (color and B/W) for cheap. good to be on their mailing list.


Dave Cooper

Re: BNC cables, terminators, Tees, etc.

Posted: Fri Aug 24, 2001 9:02 pm
by 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

Re: BNC cables, terminators, Tees, etc.

Posted: Fri Aug 24, 2001 10:56 pm
by 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

Re: BNC cables, terminators, Tees, etc.

Posted: Sat Aug 25, 2001 1:32 am
by 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.

Re: BNC cables, terminators, Tees, etc.

Posted: Sat Aug 25, 2001 2:37 am
by 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.

Re: BNC cables, terminators, Tees, etc.

Posted: Sat Aug 25, 2001 9:50 am
by 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

Re: BNC cables, terminators, Tees, etc.

Posted: Sat Aug 25, 2001 7:52 pm
by 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.

Re: BNC cables, terminators, Tees, etc.

Posted: Mon Aug 27, 2001 11:40 am
by 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

Re: BNC cables, terminators, Tees, etc.

Posted: Mon Aug 27, 2001 5:28 pm
by 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.

Re: BNC cables, terminators, Tees, etc.

Posted: Mon Aug 27, 2001 6:32 pm
by 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

Re: BNC cables, terminators, Tees, etc.

Posted: Tue Aug 28, 2001 10:12 am
by 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

Re: BNC cables, terminators, Tees, etc.

Posted: Tue Aug 28, 2001 4:40 pm
by 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