Fittings and cables and adapters for RF

After looking into the different kinds of fittings needed for the new device I realize that it might be more affordable to make my own cables. With the huge number of different connector types it really seems to make sense to buy the fittings and make my own cables.

So now I need to learn about cables. Any rules of thumb for fittings and cables? What about DIY cables? It looks like the crimper is a critical part of making cables. But maybe soldering is an option. Or do DIY cables require soldering and crimping?

I see a lot of mention of rg58 cable. Is that close to being a standard cable to use?

If over time you’re going to need cables of varying lengths and with different combinations of ends it may be worth buying in some cable and tools. However, I’ve never made up a cable with a U.FL connector — as used on the LimeSDR — and I’m not sure I’d want to try!

As a general rule of thumb, if I need a long length of cable and/or one that is to be used outdoors, I’ll make it up. Here I might use RG58 if it’s a short run and/or for use <1,000MHz. Longer runs and/or higher frequencies and that cable can have too much loss, so you might move up to RG213 or similar — as a minimum.

RG58 and RG213 are both cheaper, “classic” coaxial cables and to be honest the only time I’d probably use them now is for HF (<30MHz), or maybe RG58 with a vehicle mount antenna or for distributing a 10MHz reference in the workshop.

Where you might have previously used RG58 and RG213, I’d now tend to use one of LMR100, LMR200, LMR300 etc. There are other alternatives too, of varying thickness, rigidity, loss and cost etc.

For things like short U.FL to SMA “pigtails” using some sort of micro-coax, I’d just buy these in.

So you need to think about things such as:

  • where is the cable going to be used
  • what frequencies are being used
  • how long does it need to be
  • how much loss is acceptable
  • how much are you prepared to pay…

That said, I’m anything but an expert on coaxial cable and I’m sure others will have useful comments to add.

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Yes I agree on making U.FL cables. Plus the U.FL connectors are meant to do 30 connects/disconnects so they aren’t meant to be taken on and off as you know. So I will expose all the connections when I make a case and connect everything to the external SMA connectors.

As for making other cables I will have to look at LMRnnn cabling as I have not heard of that.

Following your info I will take a wait-and-see approach for now.

Five years from now I will probably have miles of cables. But I want to avoid that and yet I have a feeling it will happen anyway.

As an example I found a adapter to go from RP-TNC female to SMA female and its cost is twice as much as the U.FL to SMA cables. But maybe using adapter is considered a best practice over using a short cable with the correct connectors. In this case the cable with connectors would be lower cost.

I’m really just trying to learn some best practices since this is a new endeavor.

I am betting that most radio hackers have loads of connectors, adapters and cable types on hand plus throw in a crimper or two.