Selecting the right BNC cable?

[nbritton]

I'm a total newbie when it comes to BNC cables. Most of the cables I see have no specifications. I need a cable that is capable of 500 MHz bandwidth at a minimum and ideally 1 GHz for extra margin of error. Can I use any BNC cable or do I need something special?

[Paul Price]

It is not just the cable but the impedance of the cable to match your signal source/load. Good quality 50-ohm/75-ohm cables will usually do well up to approx 2GHz depending on the amount of loss/meter and VSWR you can tolerate.

[nbritton]

It is not just the cable but the impedance of the cable to match your signal source/load. Good quality 50-ohm/75-ohm cables will usually do well up to approx 2GHz depending on the amount of loss/meter and VSWR you can tolerate.

Sorry, it would be 50 ohm... to hookup a 50 ohm signal generator (1.5 MHz square wave with 500ps rise time) into a 50 ohm terminated 500 MHz oscilloscope. So in other words what you are saying is any 50 ohm BNC cable off the shelf will work at 500 MHz bandwidth?

[TimFox]

Full mil-spec 50 ohm BNC connectors themselves are good to past 2 GHz.  See
  http://media.digikey.com/pdf/Data%20Sheets/Bomar%20PDFs/BNC_Products_Spec.pdf
There are other connectors that are compatible with BNC connectors, but do not meet the full mil-spec at high frequency.  See
  http://www.amphenolrf.com/031-2-rfx.html
At 0.5 to 1.0 GHz, the loss of the cable assembly is probably dominated by the cable, specified in dB per length.

[nbritton]

What type of coax should I pick? RG-8X?

Edit: what do you think of this cable?: www.amazon.com/MPD-Digital-rg8x-bnc-antenna-cable-2FT-MILSPEC-Connectors/dp/B00TCQHE8O

[tautech]

I'm a total newbie when it comes to BNC cables. Most of the cables I see have no specifications. I need a cable that is capable of 500 MHz bandwidth at a minimum and ideally 1 GHz for extra margin of error. Can I use any BNC cable or do I need something special?

1 GHz really? Just for GP use or "something special"?   

What type of coax should I pick? RG-8X?

Edit: what do you think of this cable?: www.amazon.com/MPD-Digital-rg8x-bnc-antenna-cable-2FT-MILSPEC-Connectors/dp/B00TCQHE8O

For just GP work RG-58 C/U 50 Ohm is fine and 1M lengths with BNC's can be found on Aliexpress for ~$10 ea.

[Electro Fan]

http://www.rfconnector.com/rf-cable-guide.php

Put it in a spreadsheet and sort on the tradeoffs in frequency, attenuation, conductor type, diameter, etc.

Some to consider include LMR200, RG223, RG400, RG58, RG174, RG316.   Depends on whether you are optimizing for price or something else.  You can make your own or plenty to choose from on Amazon and eBay, along with the rest of the Internet.  Cable diameter and flexibility might considerations to keep I mind along with attentuation, and shorter is better if you are trying to squeeze out performance - but too short won't be very useful.

[nbritton]

I'm a total newbie when it comes to BNC cables. Most of the cables I see have no specifications. I need a cable that is capable of 500 MHz bandwidth at a minimum and ideally 1 GHz for extra margin of error. Can I use any BNC cable or do I need something special?

1 GHz really? Just for GP use or "something special"?   

The bandwidth on the scope that I just bought is 500 MHz, but I hear it can see well passed 1 GHz, so I would like to get a good cable that meets all use cases.

What type of coax should I pick? RG-8X?

Edit: what do you think of this cable?: www.amazon.com/MPD-Digital-rg8x-bnc-antenna-cable-2FT-MILSPEC-Connectors/dp/B00TCQHE8O

For just GP work RG-58 C/U 50 Ohm is fine and 1M lengths with BNC's can be found on Aliexpress for ~$10 ea.

I found an attenuation chart here: http://www.w4rp.com/ref/coax.html

A 3 foot RG-58 cable would be 0.645 dB loss @ 1 GHz, whereas a 3 foot RG-8X cable would be 0.405 dB loss @ 1 GHz. Not much difference, but enough for me to spend the extra $3 for a cable that is made in America and meets MIL spec and has 2-day amazon prime shipping.

[nbritton]

http://www.rfconnector.com/rf-cable-guide.php

Put it in a spreadsheet and sort on the tradeoffs in frequency, attenuation, conductor type, diameter, etc.

Some to consider include LMR200, RG223, RG400, RG58, RG174, RG316.   Depends on whether you are optimizing for price or something else.  You can make your own or plenty to choose from on Amazon and eBay, along with the rest of the Internet.  Cable diameter and flexibility might considerations to keep I mind along with attentuation, and shorter is better if you are trying to squeeze out performance - but too short won't be very useful.

I would like a cable that is flexible, I believe LMR and RG223 uses a solid conductor so those would be out. 

[sequoia]

Amazon has some pretty nice B&K Precision cables that are not that expensive including BNC to BNC (that are listed up to 2GHz):

http://www.amazon.com/Precision-CC251-Insulated-Coaxial-Cable/dp/B00TTOWEIO/   (for $17.50)

Some Amphenol cables can be found as well for about half the price:
http://www.amazon.com/Amphenol-CO-058BNCX200-006-Black-Coaxial-Cable/dp/B00O070D4W/

[nbritton]

Amazon has some pretty nice B&K Precision cables that are not that expensive including BNC to BNC (that are listed up to 2GHz):

http://www.amazon.com/Precision-CC251-Insulated-Coaxial-Cable/dp/B00TTOWEIO/   (for $17.50)

Some Amphenol cables can be found as well for about half the price:
http://www.amazon.com/Amphenol-CO-058BNCX200-006-Black-Coaxial-Cable/dp/B00O070D4W/

I don't think those Amphenol cables are legit. Here is one of the reviews for them:

Manufacturer is advertised to be "Amphenol", but that's NOT the case. Cable bears UL listing number E119932 which points to Taiwanese manufacturer COPARTNER TECHNOLOGY CORP...

BNC connectors have no markings, so they might be real Amphenol ones, but don't look/feel like that they are though...

[dadler]

I like the Probemaster BNC cables:

http://probemaster.com/bnc-cables/

[LukeW]

Every time I need a RG58 instrument patch lead and can't find one I always think of the millions of 10BASE2 cables that schools and offices must have thrown in the trash. 

[han]

Selecting cable you have to determine these factor:
1. Total attenuation accepted (to determine max length)
2. Length(for determine cable type at accepted attenuation)
3. Max VSWR (for full span frequency you need)
4. Max power


but for typical use <1G i use cheap BNC with RG58 cable (1m or less) will be sulficient