TNC strip dimensions

[RV74ME]

I just built my transponder and comm antennas using BNC connectors. Worked out great.

About to build my GPS antenna using TNC connectors on both ends and RG400 cable. One straight, one 90 deg.

Am I supposed to strip the cable the same dimensions for these TNC connectors? I found a datasheet for cables other than RG400. Don't want to screw this up and have to purchase another connector.

 

[noelf]

No. Look at the plastic bag that the connector came in. It should have the vendor and part number on the bag. Google that vendor and part number and find the data sheet for that connector.

Different vendors / manufacturers with the same "looking" connector have different coax preparation dimensions. As an example, over the years I have ordered male BNC connectors from Aircraft Spruce and received connectors from several different manufacturers. Each had different cable stripping dimensions.

As a building aid, I keep a 3-ring notebook with the PDF drawings print out for each of the different connectors I have ever received and use.

 

[RV74ME]

I googled amphenol 225555-6. The diagram showed 3 figures, but none of them listed RG400 on the left side of the table. So I?m not sure which figure to use.

 

[snopercod]

I'm not positive but I think RG142/223/400 have the same dimensions. You would have to verify that. Here's a drawing of a TNC connector for RG223 showing the strip dimensions: http://www.l-com.com/multimedia/eng_drawings/BAC554.pdf . If it were me, I'd make a practice cut on a spare piece of RG-400.

 

[noelf]

RV74ME...I appreciate your concern. It is one of the issues I have with our suppliers and their catalogues which list coax cables (such as RG 400) and coax connectors for that cable.

Here is what needs to work together:
The coax cable needs to be prepared such that the male pin will properly seat in the connector with the proper and required snap. At least today's connectors provide that tactile feedback. BNC connectors of yesterday had no such feature.

The coax cable dialectic layer which surrounds the center conductor should slide into the connector guide tube with no slop. It should just fit. This is one of the areas where different coax cable types (RG 58, RG 59, RG 400) will have different diameters and thus drive a different connector body p/n. Speaking of the guide tube...different manufacturers use different length guide tubes, and this drives the trimmed brade length and dialectic cut back dimension and outer jacket trim back.

Then there is the branded outer layer of the coax cable. Is it one layer as in RG 58 or two layers as in RG 400? With two layers, this outer "shield" is thicker, and this drives the crimp barrel dimensions. The two layers of brade are better at maintaining our 50 ohm impedance when the coax cable needs to make a tight bend.

I know this doesn't really answer your question, and I don't really have one for you. It is just something I (we) have to deal with when our suppliers sell us our components.