Bob Liesenfeld wrote:
Hi gang,
I've been thinking about making some homebrew connectors for RG-174/U
coax. I plan to use them to interconnect several enclosures made of PC
board material. I envision something like an SMB connector made from
some of the brass tubing that can be found in hobby shops. Rather than
re-invent the wheel, I thought I would ask here if anyone has done
something like this. The goal is to avoid the large size of something
like a BNC connector along with the attendant high cost of most all RF
connectors.

Tnx!

Bob WB0POQ

What frequencies will you be working at? At HF, RCA or phono plugs are
not perfect and not awfully tiny but they aren't bad and they are
EXTREMELY cheap and widely available and easily assembled. The
impedance bump from each connection will be obviously there but for
most non-measurement HF applications it simply doesn't matter.

The more connections you'll be making or the higher your frequency
(especially above 30MHz), the harder it is to argue that you should
homebrew it from brass tubing. The cost per connector will go down in
bulk, and the reliability you need from each connector will go up.
Homebrewing loses a lot of its fun when you spend more time wiggling
connectors than actually making or using the circuit. At UHF you start
becoming acutely aware of any impedance bumps and the pre-cast
connectors take care of all those details for you very nicely up to
GHz.

As to cost, SMA/SMB/other small connectors and jumpers with preattached
connectors often show up in bulk in the auction places etc.

BNC's will look large if you're laying out PCB's with surface mount
components, that's for sure, and RCA jacks aren't a whole lot smaller.
There are some variants of phono plugs out there that are smaller but
they are not as widely available or as cheap.

Good RF crimpers are not awfully cheap but should be considered in the
TOTAL budget.

Tim.