The AM Forum

assume HF freqs and no higher than 3:1 mismatch at worst.  I assume it's voltage limited but I'm not having any success in finding a simple answer.

The only thing I can find is a voltage rating of 500 volts. That is from the Amphenol web page and is good for 50 and 75 ohm connectors. 

According to ohm's law, that would be 5000 watts p.e.p. @ 50 ohms, and 3333.3 watts p.e.p. @ 75 ohms.  I wouldn't trust one at that power level.

Hmmmm, my RCA SB-1K linear amplifier uses them on the switching relay. That runs about 5A RF through it. Its a dual Dow-Key. The amp itself uses a pair of 3-400Z's @ 2800VDC. YMMV

The Amphenol UG-931 and UG-932 are BNC style connectors that are rated at 5KV.The are marketed by other companys under different part numbers.

thanks guys. there's some really good deals on ebay on coax and connectors.

Ive got a few UG931s I pulled out of a 3.5 Kv 'thing' I bought a a ham fest. The back of the panel mount BNCs look like a teflon spark plug...
(http://www.smoke.com.au/~ic/tmp/BNC.JPG)
                                                   Ian VK3KRI

Lots of guys have used "bink" connectors as HV connectors over the years. They're a whole lot cheaper than Millen connectors! In fact, the modern-day HV connectors that succeeded the Millen look an awful lot like BNC connectors.

You gonna run a "bink" line outta that Gadget Gonset, Derb?  :D

--Thom
Kilimanjaro Africa One Zulu Goat Cheese

The BNC and the N connector, for all intents and purposes, are damn near the same thing.

I've run a kilowatt and a half into a BNC..  Have run more than that into my dummy load. :)

Anything we run, at decent SWR levels, the BNC will work fine.  So does the PL259, fwwi.

There is a chart floating around on the internet somewhere that someone did tests, at some Uni in Washington, of all common connectors from DC to pretty much microwave (1 gig, I think).  The results where fairly surprising.

--Shane

I like HN for high voltage. SO239 the first thing I do is use an adapter to BNC or N. SO239 is junk. When was the last time you saw one on anything mil.

I think N is very easy.  Put a SO239 on a network analyzer some time.

for a few bucks you can get lots of 5 count jumpers of anywhere from 2 to 4 ft of rg400, the RG 58 sized silver teflon stuff with various silver connectors on the cable. mostly N's and bnc's in female shape. I have my eye on some of these and already have 30 ft of RGS-400 with bnc males coming. I'm going to get some more. I have some silver bnc female to so239 male adapters.

I am going to start a new gonset thread tonite with pix. I have a possible bandswitch total replacement, but my weak point has always been switches and relays. I am going to take a pix of the tank coil assy and the switch, and some of you gangsters might be able to show me how best to hook it up. I will lose 15 and 10 meter operation as it has 2 less positions, but it is a much better switch. You'll see in the pix. The old switch is clean, but weak and I found a  long crack in teh ceramic hiding underneath one of the shot contacts. So I'll wind up with a 80/40/20 meter amp. I like it, I dont care a whit about losing 15 and 10.

just cant visualize how best to hook up the new switch. The tank coil I get, but adding the progressively switched in 500pf caps on 80 meters for 80B and 80 C positions is fogging my brain.

The only caveat I see in using BNC, TNC, even SO-239, is that you run the risk of using non-standard HV conductors as jumpers. I'm not sure what forum this same discussion took place but that was the best logic against using off the shelf connectors. I would prefer to use connectors designed for the purpose. My HN-500 was built using the Millen connectors. I think they are good up to ~2500VDC and all of them have 25KV wire on them. You can't use them as a coax jumper or visa versa. Remember, "Safety First."

RG400 is great coax!

Interesting!  I found on the Amphenol site the spec of 500 V peak.  Odd, since this connector was designed for use with RG-58 and -59 coax, which has a spec of 1900 V. rms.

No current spec, but there was a 1.5 milliohm center pin resistance spec.  Assuming 250 milliwatts dissipation at this point (consider the 2 copper center wires going out in both directions from the connector, seems good) and using Ohms Law, this solves to an allowable 12.9 Amps of current.  The wire in RG-58 is # 20 AWG.  A ballpark conservative r.f. current number for # 20 might be 2.5 Amps?, but I think that RG-58 (matched Z) can handle at least a KW, this would be handling 4.5 Amps.

So unless you are driving an electrically short antenna, like driving a 75 meter dipole on 160 meters AND have just the right (or wrong) length of transmission line, I don’t think that you will exceed the connector’s current capability.  Looks like the 500 V. spec is usually the limiting factor.

Look these numbers over -

3:1 SWR (50 Ohm System) :

2 resistive loads -
1500 Watts to 16.6 Ohms = 158 V rms @ 9.5 Amps
1500 Watts to 150 Ohms =  474 Vrms @ 3.16 Amps.  A little over 500 V pk. spec.

2 complex impedance loads -
100 – j65 Ohms = 3.01:1 SWR,
solve for 500 V pk. = 353.6 Vrms, 879 Watts, 2.96 A rms.

 25 – j33 Ohms = 3.04:1 SWR,
solve for 500 V pk. = 353.6 Vrms, 1823 Watts, 8.54 A rms.

Just FWIW, I used PL-259 / SO239s for the HV connectors on my 4-1000 rig. It runs 3400v on the plate. The older phenolic insulated ones would break down and short out. When they blew it literally sounded like a M-80 going off!! I switched them to the newer "hamfest grade" silver / teflon ones years ago and have never had a problem since.

For wire, I took rg-213, pulled the center conductor out of it. Then I yanked the shield braid out of the jacket, slid the outer jacket back over it (sans braid). Then soldered it into the PL-259s and been good to go for many years.

                                                     the Slab Bacon

On the top row you will see the HV style of the BNC and N connectors.On the bottom row are the standard BNC+ N connectors. The numbers for the HV BNC are UG-931+UG-932. The numbers for the N style are UG-59 + UG-560. A UG-496 can be used in place of the UG-560.

FWIW, the voltage that solid poly (not foam) RG-8 or RG-213 can handle is impressive, regardless of book rating. Many broadcast transmitters use the stuff for HV wiring. It's used in a Harris 35 KW FM transmitter with 13 KV on it. and nary a problem, except you need to make sure the shield is peeled back from the center conductor for some distance to insure a long creepage path.

I've run many, many KW through N connectors. Since the BNC is pretty much the same (most of you know an N male will plug into a BNC female), the power limiting factor is going to be the small size of the coax that can fit into a BNC. That's where the teflon coax types really shine.

Why did you do this?

Hey Joe nice connector pictures. I really like the high voltage connectors when I can find them.

Nice Gut shot also

I'm going to be running RGS-400 for everything. I like the way it solders and handles a weller guns heat. The deals on ebay for such stuff are awesome.  I've run into deals where buying RG-8 would be 3X more expensive, and you get 2 silver N or BNC connectors already on teh cable.

Another great "high power" connector is the RCA Phono. Motorola used these as RF connectors for years inside many VHF and UHF radios. Hallicrafters and Heath even used them as RF output connectors. The ceramic insulated variety were typically used at power.

My SR-150 XCVR had a phono connector on the output. When I changed it to 6146 finals (from sweeps) I changed out the phono connector for a BNC. It has worked great at 150W PEP for years.

Mike WU2D

I'm running a BNC on the TR7A and V2 CDC