Coax to phono connector wanted

[Guest]

I have a set of CCTV cameras that I want to test out on a TV
The cameras have a strange kind of coax fitting on them similar but not the same as a TV coax. With no way of posting a photo of it hear, things are very hard to explain, so I will do my best and hear is the model number of the camera Indigovision 2amp box camera BX620-HD-FC Dahua DH-PLZ1040D 2.7-12mm F1.6 VF Lence

The fitting on the TV for it to work (The coax port will not work) is a typical phono port

Any thoughts please?

[James Perrett]

According to

http://www.multiplize.net/indigovision/ ... t-A4_2.pdf

it uses a 75 ohm BNC connector.

I've used this adaptor

https://cpc.farnell.com/pro-signal/psg0 ... csku=false

with some of these cables

https://cpc.farnell.com/pro-signal/psg0 ... t=psg00561

which have worked fine for both digital audio and video.

[Kwackman]

Hi,
There's info here about how to show an image on this site.
https://www.youtube.com/watch?v=s7vVDGTOHW0

[Guest]

According to

http://www.multiplize.net/indigovision/ ... t-A4_2.pdf

it uses a 75 ohm BNC connector.

I've used this adaptor

https://cpc.farnell.com/pro-signal/psg0 ... csku=false

with some of these cables

https://cpc.farnell.com/pro-signal/psg0 ... t=psg00561

which have worked fine for both digital audio and video.

Great Links!

But will this
https://cpc.farnell.com/pro-signal/psg0 ... csku=false

Connect to this
https://cpc.farnell.com/pro-signal/psg0 ... t=psg00561

I mean I need it to have a cable and not just port to port.

On the
https://cpc.farnell.com/pro-signal/psg0 ... csku=false
What kind of port is on the other end, if its a femail phono port then it will fit this on you posted
https://cpc.farnell.com/pro-signal/psg0 ... t=psg00561

Thanks

[James Perrett]

Yes, the adaptor has a female phono on one end and a male BNC on the other. When you combine it with the cable I linked to it gives you a BNC to phono cable. You can also buy those cables in a variety of different lengths if you want something longer or shorter.

[Guest]

Yes, the adaptor has a female phono on one end and a male BNC on the other. When you combine it with the cable I linked to it gives you a BNC to phono cable. You can also buy those cables in a variety of different lengths if you want something longer or shorter.

Yes I know about the cable, I have quite a few of them laying round hear gathering dust, my local pound shop in the high street stock a vast majority of them as well. It was just that fitting that I am short on

Thanks!

[Guest]

Yes, the adaptor has a female phono on one end and a male BNC on the other. When you combine it with the cable I linked to it gives you a BNC to phono cable. You can also buy those cables in a variety of different lengths if you want something longer or shorter.

What do you think about this one
https://cpc.farnell.com/pro-signal/rw1- ... dp/CN15992

For some reason its 10p cheaper then the gold coloured one

[James Perrett]

That would probably work - I suggested the others because they are ones that I've actually used.

[Guest]

Hah!! I read a little more of it and it actually says that it is gold plated! so for 10p more you get a small piece of gold trading at around £1500 per oz on the markets. Not to mention gold is a very good conductor or electricity which in this case will mean a better connection and hence a better signal

But sadly I went though the process to order it and they wanted an extra fiver for handling charges

[Wonks]

Gold isn’t quite as good a conductor as many other metals, but it doesn’t corrode or oxidise in normal circumstances. So there’s a good case for using it where you have a permanent installation that will rarely be disturbed, and where your standard chrome-plated or even plain brass contacts will oxidise over time.

But gold is a soft metal, and will quite quickly wear away where you have connections that are constantly being made and broken. But this making and breaking action will normally remove corrosion through physical wear on chrome, steel, copper etc. contacts. Once the gold plating has worn away, it normally leaves a surface that's far more prone to corrosion/oxidation.

So, gold plating is not always the best choice for connectors, but it’s rarely a bad choice.

[Mike Stranks]

About 20-25 years ago, before HDMI came along, as a not-using-fully-pro-gear camera person and video-mixer, I used the adapters as highlighted by James P all the time when needing to interconnect bits of kit. Always reliable and never failed.

If you don't like CPC's handling charges, then you'll find similar on eBay and Amazon. But in many years dealing with CPC I've always found them good value and very customer-focussed on the very rare occasions that things go awry.

[Hugh Robjohns]

I also find that CPC generally stock good quality
reliable components, where it's a bit more hit and miss on ebay and amazon.

[James Perrett]

But sadly I went though the process to order it and they wanted an extra fiver for handling charges

I usually have a CPC shopping list on the go and send off an order as soon as it gets to the minimum for free postage (£17.50 I think). They sell so much useful stuff.

[Guest]

Gold isn’t quite as good a conductor as many other metals, but it doesn’t corrode or oxidise in normal circumstances. So there’s a good case for using it where you have a permanent installation that will rarely be disturbed, and where your standard chrome-plated or even plain brass contacts will oxidise over time.

But gold is a soft metal, and will quite quickly wear away where you have connections that are constantly being made and broken. But this making and breaking action will normally remove corrosion through physical wear on chrome, steel, copper etc. contacts. Once the gold plating has worn away, it normally leaves a surface that's far more prone to corrosion/oxidation.

So, gold plating is not always the best choice for connectors, but it’s rarely a bad choice.

This is only to test the cameras and line them up so will not be a permanent fixture. But on what you said I think the grey/ silver connect would suit best

[Guest]

About 20-25 years ago, before HDMI came along, as a not-using-fully-pro-gear camera person and video-mixer, I used the adapters as highlighted by James P all the time when needing to interconnect bits of kit. Always reliable and never failed.

If you don't like CPC's handling charges, then you'll find similar on eBay and Amazon. But in many years dealing with CPC I've always found them good value and very customer-focussed on the very rare occasions that things go awry.

I also find that CPC generally stock good quality
reliable components, where it's a bit more hit and miss on ebay and amazon.

The problem I have with ebay is a lot of the stuff is rubbish from China
But I have a TLC-direct catalog hear, but I dont know where to look in it for such a part

[Guest]

I had a go making up the cable, soldering together a coax cable onto a phono cable. But with out being able to post an image of it hear it is very difficult for you to image what the soldering is like

I tried it on the TV and I now have a signal coming into the TV. But it is just a fuzz

[Hugh Robjohns]

TV signals have a wide bandwidth and at the high frequency end the cable construction becomes critical... and welding two dissimilar cables together isn't going to help matters at all. Internal reflections, and weak signals are almost guaranteed.

75 Ohm BNC cables with BNC-phono adapter plugs is definitely the best solution.

https://www.tlc-direct.co.uk/Products/TSBN20.html

[Mike Stranks]

But without being able to post an image of it here it is very difficult for you to image what the soldering is like

A link to a 'how to' video...

https://www.soundonsound.com/forum/view ... hp?t=75253

[ef37a]

I had a go making up the cable, soldering together a coax cable onto a phono cable. But with out being able to post an image of it hear it is very difficult for you to image what the soldering is like

I tried it on the TV and I now have a signal coming into the TV. But it is just a fuzz

BNC plugs can be tricky to solder at the best of times, you have to get the screen and core lengths dead right. Much easier to buy a BNC-BNC cable, chop it and fit RCA or whatever to taste.

Dave.

[Guest]

TV signals have a wide bandwidth and at the high frequency end the cable construction becomes critical... and welding two dissimilar cables together isn't going to help matters at all. Internal reflections, and weak signals are almost guaranteed.

75 Ohm BNC cables with BNC-phono adapter plugs is definitely the best solution.

https://www.tlc-direct.co.uk/Products/TSBN20.html

I used an old phono cable and a coax cable soldered together

So the higher frequency the better the connection needs to be right? opposed to 50hz DC and AC electric, where I have never had a problem joining wire together

I bit the bullet and spent the extra fiver. So when it arrives you think I should I will have a better signal?

[Guest]

But without being able to post an image of it here it is very difficult for you to image what the soldering is like

A link to a 'how to' video...

https://www.soundonsound.com/forum/view ... hp?t=75253

I watched your good video. It looks like a image hosting site but it looks like I need to set up an account. There are image hosting sites out there that you don't need an account to host, did you know?

But as the above poster has stated what I have done will likely not work, is there any point at this stage posting the image of what I have soldered?

[Guest]

BNC plugs can be tricky to solder at the best of times,

I did not solder onto any plug as I don't have the BNC plug at present

you have to get the screen and core lengths dead right

Are you saying this is a frequency thing, where you need to make the length of the wire in tune with the length of the frequency? Bit like cutting a CB aerial?

[ef37a]

BNC plugs can be tricky to solder at the best of times,

I did not solder onto any plug as I don't have the BNC plug at present

you have to get the screen and core lengths dead right

Are you saying this is a frequency thing, where you need to make the length of the wire in tune with the length of the frequency? Bit like cutting a CB aerial?

No, it's not that fussy, just that there are about 4 or 5 parts to a BNC connector and you have to get the wire right or it won't go together or it will short.

Dave.

[Guest]

No, it's not that fussy, just that there are about 4 or 5 parts to a BNC connector and you have to get the wire right or it won't go together or it will short.

Well now I'm confused! I though you had live and earth (or ground)

[ef37a]

No, it's not that fussy, just that there are about 4 or 5 parts to a BNC connector and you have to get the wire right or it won't go together or it will short.

Well now I'm confused! I though you had live and earth (or ground)

Ha! Ha! viz...https://uk.rs-online.com/web/p/coaxial- ... rs/5464875

Dave.

[Hugh Robjohns]

Well now I'm confused! I though you had live and earth (or ground)

It's signal and screen, but yes, two connections.

However, video (and digital audio and RF) are all high frequency signals that require the cable to have specific characteristics if the signal is to get to the other end intact.

One of those characteristics is called 'characteristic impedance' and its why the cable is identified as 75 Ohms or whatever. The connectors must have the same characteristic impedance too.

The characteristic impedance is determined by the dimensions of the cable and plug/socket – the spacing between the signal core and screen – and the insulating materials between and around them.

That's why BNC connectors have a specific insulation sleeve and screen terminating ferrule, and why the cut cable dimensions are critical. They are fiddly to assemble with the proper tools, and a nightmare without.

Crudely joining two dissimilar cables will create an impedance mismatch, degrading the cable's ability to convey the signal.

RCA-phono plugs/sockets aren't actually 75 Ohm connectors, but they're close and cheap enough for non-professional applications. That's why they're used on consumer video and digital audio equipment in place of the standard professional 75 Ohm BNCs.

And that's why the best solution for interconnecting video gear using BNCs with RCA-phonos us to use standard BNC cables with phono adapters as I linked above. That way the characteristic impedance is maintained and everything works.

[Guest]

However, video (and digital audio and RF) are all high frequency signals that require the cable to have specific characteristics if the signal is to get to the other end intact.

Are, the higher the frequency the shorter the wave band, they don't tend to travel very far or travel well though buildings and hills unlike long wave radio or base notes do they

[James Perrett]

I used an old phono cable and a coax cable soldered together

As Hugh says, just any old phono cable won't work. It needs to have low loss at high frequencies and a characteristic impedance of 75 ohms. That's why the CPC cables I linked to use RG59 cable which is likely to be similar to the cable used by the BNC cables.

A random join in a video cable is likely to have a very different impedance which will result in much of the signal being reflected back to the source and very little actually getting through. There are ways of joining video cables to preserve the impedance but it requires very careful trimming of the cable and very neat soldering.

Oh - and just to confuse things further - BNC connectors and cables are available in both 50 ohm and 75 ohm versions. You need to make sure that you have the 75 ohm version for video and digital audio.

[Guest]

As Hugh says, just any old phono cable won't work. It needs to have low loss at high frequencies and a characteristic impedance of 75 ohms. That's why the CPC cables I linked to use RG59 cable which is likely to be similar to the cable used by the BNC cables.

Oh - and just to confuse things further - BNC connectors and cables are available in both 50 ohm and 75 ohm versions. You need to make sure that you have the 75 ohm version for video and digital audio.

But what about when the connector arrives and if I use one of my cheep phono cables to connect to the fitting. I mean I bought them from the pound shop and not Dawsons. But they are OK for sound, but will there be any different for video?

[James Perrett]

But they are OK for sound, but will there be any different for video?

They're no good for video.