UHF connector (PL259) DC voltage rating? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: February 06, 2022, 12:14:52 am
content: So my keithley power supply (240A) has a connector on it that claims is a teflon UHF connector. A banana plug fits in the center pin.If I wanted to actually use the proper cable and connector for it, would a regular UHF connector + cable work ? When I looked up the connector rating its 500VACRMS or ~710VDC.. but the power supply can put out 1100V, however only at 10mA.Does anyone have experiance with the connectors and cables for HV DC bias/low power? Is the cable de-rated to tell you what its good for at high frequencies maybe.. so the DC rating is lower.. like scope probes? I can't find a PL259 connector that has a rating better then 500V.

author: ocw
author_rank: Regular Contributor
timestamp: February 06, 2022, 12:35:30 am
content: You need a PL259 and coax with Teflon insulation:https://www.mouser.com/datasheet/2/18/1/C83_822-2451243.pdf

author: coppercone2
author_rank: Super Contributor
timestamp: February 06, 2022, 01:03:47 am
content: thats double the rating of the normal PL259 connectors, very nice

author: tkamiya
author_rank: Super Contributor
timestamp: February 07, 2022, 07:56:05 pm
content: That's pretty scary. How about replacing it with HN which is a high voltage version of N connector and these are physically same size as UHF connectors. I don't like the fact that center connector is so close to the surface for high voltage applications. Also, center pin makes contact first, which is not ideal.

author: coppercone2
author_rank: Super Contributor
timestamp: February 07, 2022, 09:30:15 pm
content: hmm you might be right, the rating is there but its a poor safety factor compared to the 5kV component. That PSU sure looks like it could ruin my day so its probobly a good idea to replace that front panel connector with HN.I see the HN connector is not compatible with banana plugs, which is probobly a good thing. Tempting to use banana plugs when you use it at lower voltages but I think keeping it properly insulated and secured is the way to go.I also don't like the idea of just braid conducting the ground on the cable. Do they have coaxial cables that have additional wires in addition to the braid? Kind of like cheap coaxial cables used for audio, that have strands as a shield (non woven). This is probobly more durable.

author: TimFox
author_rank: Super Contributor
timestamp: February 07, 2022, 10:37:58 pm
content: In grad school, we used "SHV", sometimes "MHV", coaxial connectors with RG-59/U coax for 3000 V connections (low current). SHV was preferred, since many students could not tell the difference between MHV and BNC, which will mate if you use a Channel-lock pliers on them.Be careful about the cable: regular RG-59/U has a solid polyethylene insulator. Foamed-polyethylene dielectric in 75 ohm cables has lower loss at RF, and faster propagation velocity, but can't hold the voltage. (Guess if I learned that one the easy way or the hard way.) Solid teflon is good for high voltage, but foam teflon ("Gore Flex") has the same problem due to the gas content.

author: Paul B
author_rank: Contributor
timestamp: February 07, 2022, 10:46:44 pm
content: personally there are a lot beater connectors for High voltage rather than a PL259and safer without protruding pin or socket connectionsok you would have to look at secondhand connectors for a good price but worth the effortPaul

author: coppercone2
author_rank: Super Contributor
timestamp: February 07, 2022, 11:36:55 pm
content: well I don't mind the 50$ price tag on digikey for the HN connector because the voltage levels are high on this instrument.. is it the best choice?See what i don't like about coaxial cables is that they can slip out of braid and leave a exposed center pin. I have seen it happen on something that looked crimped well.. but fortunately I noticed that it was a weakened joint and yanked it out. This was from a time microwave cable sold on ebay IIRC. But it felt shitty, like aluminum thread or something... real rough to connect like cheap versions of expensive starett things (i.e. pin vise).So I will probobly buy the proper connectors from digikey for high voltage human contact stuff... no second hand for this purpose.. Kinda wish there was a coaxial connector with a set screw or something with a SDS shank so that you can lock the center pin into place so its not all pulling on the braid... then you have to rip a big copper pin out rather then just tear some braid up... without making the cable more complicated (horrible).Or I suppose you can put a hard attached cable clamp on the outside of the instrument and whenever you connect the cable you strain relief it. Ugly but so is HV.

author: Paul B
author_rank: Contributor
timestamp: February 08, 2022, 12:57:28 am
content: Hi i do not know what voltage you want the connector for but is this any goodhttps://www.ebay.co.uk174942491383Paul

author: Paul B
author_rank: Contributor
timestamp: February 08, 2022, 01:08:15 am
content: better still I have used Lemo connectors for High voltagedo a search on Ebay for Lemo High Voltage Plug And Socketand this one looks like it could easily do 5KV it is on Ebay UK but Ebay USA can find itLemo High Voltage Connector Plug And Socket Set FFA.3y 430 ERA.3Yregards Paul