3-Lug BNC "Triax" to BNC Adapters  - Page 1
Forum section: electronics / general

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: July 18, 2019, 08:01:58 pm
content: I'm looking for a "affordable" BNC Triax to BNC adapter (male-female) in the configuration force-force, shield-shield.Use case would be to connect my Keithley 236 to my HP8753D's bias tee's.Unfortunatly all the low cost options seem to connect force-force, guard-shield for a reason(?) The cheapest one on digikey seems to be the ADBJ20-E2-PL75 for >60USDOne option would be to just make an adapter myself using this BNC Triax:https://www.digikey.com/product-detail/en/mueller-electric-co/BU-P5219/314-1688-ND/9675945a bnc connector and a tin housing.Ebay has some offerings for about 30 USD, but the shipping doubles that price an at that point I can buy new ones.

author: JxR
author_rank: Unknown
timestamp: July 18, 2019, 08:32:02 pm
content: I just found myself in a situation where I wanted to breakout all the connection on a Keithley 238 to banana jacks for everyday use, where extreme sensitivity and leakage is not a big concern.Sadly, it was actually cheaper for me to buy 3x triax cables, a Hammond box, panel mount triax connectors, and some banana jacks than it was to buy a pre-made solution. You may find like I did, that it is just cheaper to build something yourself.I looked at those adapters that remove the guard connection and they are ridiculously expensive. I would say that the ones that tie the guard to the outer shield could have their uses though. You could use something like a Pomona 5229 (~$10) to Pomona 1894 (~$10) and have a fairly simple way to bring the center conductor to a single banana connection that maintains the guard through the entire length of the cable (up to the Pomona 1894).I have a simple shielded test fixture I built where I can just jumper the connections together between different devices. The test fixture has triax, banana jacks, and I plan to add a couple bnc connectors in the future. Not as simple (and small) as a nice adapter, but it does what I need.A small metal box that has a triax connector on one end, a bnc on the other, where you run a wire between the two center conductors may be cheaper than an adapter.There are a lot of people here with more experience than me though, so maybe they will have a better solution for you.

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: July 18, 2019, 08:55:08 pm
content: QuoteI got my 237 / 238 pretty cheap and I managed to buy a lot of 12x10ft triax cables complete with connectors for about 200 USD. So I cut 3 of them in half and use them nicly wraped and with crocodile clamps for every day use.I bought some of those Mueller 18USD connectors from digikey intending to build a measurment box for more sensitive stuff.I do not think I will use the VNA a lot with the smu. It's more curiosity to test some transistors at different bias points and look how they work at different bias points. I will probably just use my every day crocodile clamp setup and BNC to croco adapters in the endBut thats kind of the thing here. The SMU's have lost a lot in value but the accessories ... Not so much.QuoteWell 10 bucks would be ok to me. If I did not had triax to spare right now I probably would do something like that.

author: JxR
author_rank: Unknown
timestamp: July 18, 2019, 09:12:54 pm
content: You could build something like this Pomona 3752. Just have bnc on one end, and triax input on the other. The shield will be attached through the box and outer conductors. Then run a wire between the two center conductors. If you can source the parts, I would guess you could do it for less than $30.