How do you terminate your coax to BNC?

[PekkaNF]

We were pampered 30 years ago in school electronics lab. No shortage of test leads.

There is usually vety little point of rolling your own BNC/RG58 stuff, but on RG174 or RG316U cables, and panel connectors etc.

I'm having a hard time finding crimpping pliers for AF 1,75 mm pin and 5,6 mm sleeve.

https://www.tme.eu/fi/details/5-1634500-1/bnc-liittimet/te-connectivity/

Dimenssions:
https://www.tme.eu/fi/Document/11a4780343b55fee08f6e9023cade175/5-1634500-1.pdf

[Will_D]

Surely Farnell or Radionics would stock crimpers ( at a price  )

Cheers

Will

[eskoilola]

Pekka,
I have (at home, now in Frankfurt) about 200 different BNC connectors, variety of coax cables - and no crimping equipment.

I think I have tried it all.

The best so far has been to:
1. peel off about 20 mm of the outermost palstic shield
2. solder the center pin so that the coax insulator "meets" the pin
3. Push the pin and the coax (now soldered) into the connector
4. Pull the coax copper shilding over the connector
5. Wrap copper wire around the part of the coax shield which is overlapping the connector shield
6. cut off excess coax shield
7. Solder the shield into the connector

Although the coax insulation may melt somewhat I have never succeeded to create a short there

The result will NOT win any beauty contest but it works. You may camouflage the connection by shrink tubing.

[PekkaNF]

Kiitti Esko,

I'll try that one. I have hacked few connectors 50% right: they had pint that could be soldered.

This far I have managed with mutilated readily crimpped cable etc. but I see that I am spending more time with different pieces of cabling, connectors and stuff.

At work there were trained porfessionals that would do hard part. Now I am on my own with my hobbies and I realize that there were questions I should have made (and surplus material I should have begged).

Next quesion: At the end of the thin 50 ohm coax I need short pigtails, which (readily) available wire would be good? Flexible ethernet twisted pair?

[eskoilola]

Making pigtail on a coax cable is quite easy. I found a video in YouTube which shows the method I have been using - the only difference being that I bend the coax shielding backwards and make the joint over the coax insulation.
The pigtail needs some support and insulation. Shrink tubing is OK but for better durability I use plastic tube over the end of the coax, gaps filled with Sikaflex. The Sika creates a flexible joint which makes the wires last longer.

The Youtube video is here.

[PekkaNF]

Cripping looks pretty easy on video

Looks like much of to confusion comes from manufacturer documents. They simply can't convert imperial unit int metric units. This combined with my deep distrust on spesifications and sales information makes desission making unncessary hard for me.

Looks like good brand RG174U cable can be crimped to TE BNC connector with HT336G plier.

Looks like minimum order for the quality RG174 cable I want is 250m. Therefore I'm considering  alternatives:

1: RG316U HELUKABEL 40203 3.39 €/m in 5 m increments.
https://www.tme.eu/fi/Document/151b7fc68e82e16d70ee1f3bf3c18100/M_004-005-006-007_RG-coaxial_cables.pdf

2: Belden 9239, looks expensive (1.97 €) for what it is (RG174U/PVC), but can get 30,5m reel.
https://www.tme.eu/fi/Document/32871dfd99d2b35ed5387313722281b3/9239.pdf

Thinking of 10 metres of #1 to start with. Any reason why #2 would be better for short measurement test leads?

Pekka

[PekkaNF]

Making pigtail on a coax cable is quite easy. I found a video in YouTube which shows the method I have been using - the only difference being that I bend the coax shielding backwards and make the joint over the coax insulation.
The pigtail needs some support and insulation. Shrink tubing is OK but for better durability I use plastic tube over the end of the coax, gaps filled with Sikaflex. The Sika creates a flexible joint which makes the wires last longer.

The Youtube video is here.

Thank you, that video reminds me of LiFYCY/shielded control cable termination I did as a electrician trainee. No-one ever answered why normally we had to solder pigtail on instrumentation cable shield, even when termination would haven been neater with isulation sleeve and crimp ferrule at the end. Except on one "robot" that were required to clamp down the outer shield, shrink tube to keep all together and inner shield shelds had to be knited out like that on video, crimped and tightened under screw terminal.

I have to think of that fold back shield pig tail. It might come handy son some thight places.

[PekkaNF]

Got cable, connectors and a pliers, but haven't terminated cables yet. Have to find the crimp dimenssions to test the connection. At work we used to check pliers when new and then every 1000 crimps or so. I never did BNC-connectors, but belive that crimp connector is a crimp connector.

Now the next problem: There are plenty on 50 ohm BNC connectors for PCB and panel mounting. Even panel mounting with both connectors as a solder luggs (and isolated). But very few male connectors for any other than cable. I know that there are very little need for it, but when making probe contraptions for oscilloscope, they would coe handy.

There are some chinese ebay stuff, but I really rather buy brand name stuff that connects to oscilloscope.

I found some, but silly price:
https://www.digikey.com/product-detail/en/hirose-electric-co-ltd/BNC-BPR-3-40/H122549-ND/5148473

Probably could use probe compensator, but that would effectively wreck a good probe.



NO-NOT-that one, but that kind of "box"

[eskoilola]

Are You afraid that the Chinesium somehow contaminates the oscilloscope ?

It is just a connector after all. Some of the dimensions are critical and maybe there should be a layer of precious metal here and there and maybe some of the insulators should be made out of something like Teflon. But, unless You are going to make something that enters the orbit the ones made of Chinesium perform just as good as the brand name. And, in the worst case, the brand name components might be manufactured in the very same factory as the cheap ones, there is just this label...

[PekkaNF]

Your concern about contageneous properties of cihinesium are founded.

However toxcity for my allready tainted Rigol DS1052E is not lethal, IMHO. It might be a different case if it were western made, then I would not bring any products from far east near it.

I am concern that connector would not fit properly and would wear out BNC:s on my scope.

Another thing is that ebay stuff is pretty low quality in general. Today I found a 50ohm terminator that didn't terminate (it had a stadard small resistor inside it, but the connection was not made... AND few days ago I fount that one BNC/screw terminal adapter had a deformed coupling nut. Seriously oval. mad to give them a spin in the lathe.

I have seen abysmaly bad enginering from pretty much any country I have been working. And some good one. It's just pretty hard avoid buying crap, no matter what brand. Alhough some brands are pretty good on peace of mind department, but on electrical stuff they commad price that I can't afford. For me it is harder to find a decent quality stuff, spesification must be sacred, I don't care all the features and usually I don't need latest and greatest stuff.

[PekkaNF]

Three pictures of ebay stuf...

Bought some cheap terminators and found one not working. Maybe someone failed to make connection? Those were not cheapest. Pretty sure you can't give them 10Vpp signal.

Needed those BNC/screw terminals to test twisted pair cable (termination) and stuff. Nicer to build test stuff with a screw driver than trying to solder wires into BNC body.

[eskoilola]

Oh.
In case You are concerned about the wear of the oscilloscope connectors - make a short adapter that then takes the wear. At least that is what I do. BNC connectors are the easy ones. I have a N-connector in my Rohde&Schwartz RF generator. That connector is not intended to be regularly plugged in/out. So there is an adapter with a (do NOT laugh) 6mm audio jack.

In the scope I usually have the probes connected and I seldomly remove them. Old and trusty Tektronix stuff.

[PekkaNF]

One more thing...

I need a small fixture that has male BNC at the other end and female at the other end.



I see those two in US at the same price than one in EU. 20€ for one is just about pricey, but palatable. 40€/£ a piece not.

Any other choses? Or that is the ongoing rate for decent one?

I would not mind of constructing one, but male panel mounted BNC:s does not seem that common.

I am about to buy 5 panel mounted BNC connectors each gender, but very little credible specks on ebay products.

Pekka

[Roger B]

If you are looking for some quality connectors try these people:

https://www.distrelec.ch/en/connectors/rf-coaxial-connectors/rf-connectors/c/cat-DNAV_PL_041004?q=*&sort=Manufacturer%3Adesc&filter_Series=BNC&filter_Category3=RF+Connectors&filter_Buyable=1&filter_Manufacturer=Huber%2BSuhner

There are a selection of the top manufactures there at reasonable prices.

[PekkaNF]

A little followup!

Roger, I just had ordered from that comppany some connectors and small stuff. Funny that I did not notice that connecor though.

I got some connectors and stuff for my previous projects.

Lately I have been making some low quality contraptions and all sorts of ebay specials have been dripping trough. There are some feed-tough terminator/filtering/impedance maching circuits I have tried out and alhough they work out ok when soldered trough terminals, some DIY solution that will be mechanically sound for test/measurement use has a little appeal.

Found some really nice and professional products.
https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_ID=8681





I have some connectors and strip/dot prototype PCB boards, but they don't seem to mach BNC/SMA solder connections, as nicely as these:


https://www.pulseresearchlab.com/collections/signal-conditioning-kits

That page has a nice coockbook on attenuators
https://cdn.shopify.com/s/files/1/0355/3849/files/AttenuatorAppNote_f7228dae-43d6-4e97-8e53-79a152d308ca.pdf?13945134751436219249

Almost bought few of these to play with, but I actually would need only some proper small circuit boards that would mount the connectors.

https://www.ebay.com/itm/PC-Oscilloscope-Accessories-Coaxial-Attenuator-400V-2-BNC-M-F-Connector/172922559823?epid=659280964&hash=item2842fcdd4f:g:ai4AAMXQBNlRh1cR

But they look like bit friable to prototyping.

Q: Any recommendation for low cost readymade PCB that would easily accept BNC/SMA PCB solder connectors. OR BNC/SMA connectors that are short and have standard pin spacing AND means to attach them mecanically.

Suggestions?

Pekka

[awemawson]

Back 'when I was a lad' I used to solder old pennies (240 to the £) onto the ends of 3/4" copper plumbing pipe that I'd scooped a section out of in the middle to give access for mounting pi networks etc within. Simple, cheap and robust.

[PekkaNF]

Thank you, That is neat. How do you take clean bite out of copper pipe? Hole saw?

Sometimes something is better than perfect, but much too late....



https://e2e.ti.com/support/power_management/simple_switcher/w/simple_switcher_wiki/2243.understanding-measuring-and-reducing-output-voltage-ripple

[awemawson]

When I was doing that I was probably 13 or 14. No machine tools, no electric drill. It was all hand tools and a 'brace and bit' carpenters drill and a woodwork vice.

I probably had four or five files at home and  my soldering iron was a copper lump on the gas stove. I did manage to sneak the tube with the pennies already soldered on into the school workshop and turn the pennies down to the tube diameter .

A bit later a friend of my fathers took pity on me and gave me a Henley Solon 25 watt electric iron - sheer luxury 

[PekkaNF]

That lad! Remember using potato smasher size iron and scavenged componenets from tube radios for my "experiments".

I tried to buy thin tinplate, should be bendy, good looking, does not need painting or anything, conductive and easy to solder grounding wires (snippet-tabbet....on the edge...bend...solder...done). Even found source 500*800 mm nevew shiny straight plates. 0,3 mm thick. Bit pricy (30€ a piece), fine. But they only freigh, which is 40€ and the place is not that far, I could visit, but they have "no visitors" policy. They can stuff it.

But if find other source for thin tin plate, I'll buy it. Used to work a little with tin plate and I think it is pretty nice to work with basic hand tools (alhough miniature sheet metal bender and shear would be nice).

Copper is nice in priciple, but it sinks heat like there is no tomorrow, pretty resilient on drilling...bigger holes needs a punch and looks clapped when it gets old.

Pekka

[awemawson]

A good source of reasonably sized bits of tinplate is the drums that cooking oils come in. I mean the large 20 or 25 litres ones delivered to catering establishments for deep fryers.

If you can get them before they are dented they are quite easy to open up and unroll.

[PekkaNF]

Thank you. My wife is a cook on the hotel, have to ask her to bring one home and try it out.

Pekka

[PekkaNF]

Goinf off the tanagent....

got some SMA terminated cables and BNC/SMA adapters.

Desided to disassemble one BNC/SMA adapter, because it looks like it could be a trough terminator with addition of one or two resistors.

Did no pull out easy, long nose plier slipped and made unssightly groves...now it's war: thought that it has been readed and glued. Heated it up a little bit.

Looks like the isulation is not teflon. This one does to go together, but I learned that has been assmbled with a press.

[PekkaNF]

Made a little extractor: aluminium bushing that slips over SMA and 1/4" 36 nut to pull SMA connector out.

Wonder if I can punch (press?) small tab washer type carrier that alows me to solder terminating resistors inside of the connector.

Pekka