RG-58, RG-400 and connectors

N999BT · #1 04-09-2019, 10:16 AM

I was looking through a catalog and noticed that some BNC connecters say they are made different for types of cable:

One connector description says: Right angle, BNC connector plug for use with Belden 9907, Belden B7806A, LMR-195, RG-141, RG-303, RG-58, RG-58A, RG-58B, RG-58C coaxial cable.

and another that says: RF CONNECTOR/BNC male straight crimp plug for use with RG-58, RG-142, RG-400, 50 Ohm.

Two questions:

1) The first connector does not mention RG-400, but does mention RG-58. Does this mean that the connector should not be used on RG-400, and if so why?

2) How big is the performance difference between RG-400 and RG-58? When I built my plane 17 years ago, I'm not sure RG-400 even existed.

lr172 · #2 04-09-2019, 10:30 AM

RG-400 has a thicker OD and needs a larger crimping sleeve. I suspect that the nipple extending under the braiding is also a different size. Usually those for 400 don't also support 58. I guess some are designed to support both, but would look at the data sheet to be sure it's not an error.

Larry

fl-mike · #3 04-09-2019, 10:37 AM

RG-400 is much superior to RG-58. RG-400 is double shielded and the insulation is PTFE vs PVC.
The diameter of the inner conductor and insulation on RG-400 is just slightly different from RG-58.
I have found that crimp connectors for RG-58 will generally work fine for RG-400. As you noticed, some companies list both cables for a particular connector. Worth a try. The impedance mismatch will be undetectable between the two, it is more physical size of the shield sleeve, center pin wire hole, etc.

majuro15 · #4 04-09-2019, 11:33 AM

I recently had to return 90 degree connectors advertised to fit both RG-58 and RG-400. The 400 is a bit thicker, as others have mentioned. It was a tiny bit but enough of a difference the sleeve wouldn't go over the nipple and brading. My crimper from Stein works great on the 400.

dtw_rv6 · #5 04-09-2019, 01:41 PM

I used a heat gun to warm the jacket on the last RG400 cable I assembled. It didn?t soften much, but eventually I was able to get it assembled.

MCA · #6 04-12-2019, 01:55 PM

I've found there is a wide range of quality and fit among BNC and TNC connectors, strangely enough. My recommendation is to purchase a handful of different ones and try them all out. When you find the one you like, buy more and use that for the real connections.

Also try buying from folks who use a lot of connectors, like Stein or Aerotronics.

I don't recall the ones I settled on otherwise would post here.

rocketbob · #7 04-12-2019, 02:18 PM

AMP 31-320-RFX is the most correct and most widely used RG-400 straight BNC connector.

az_gila · #8 04-12-2019, 09:40 PM

Quote:

Originally Posted by rocketbob

AMP 31-320-RFX is the most correct and most widely used RG-400 straight BNC connector.

And they are pretty cheap....

https://www.digikey.com/product-deta...1039-ND/100539

I went through the same exercise when I switched to RG-400

N999BT · #9 04-15-2019, 12:30 PM

Thanks for the replies. It helps.

bsvantho · #10 04-15-2019, 02:15 PM

Quote:

Originally Posted by az_gila

And they are pretty cheap....

https://www.digikey.com/product-deta...1039-ND/100539

I went through the same exercise when I switched to RG-400

You may also need some TNC connectors for RG-400. These worked fine for me and are also cheap:

https://www.alliedelec.com/product/a...2372/70031738/