bobmarkert

bobmarkert

Well Known Member
Which is preferable, a tight bend radius like the pic below or accept the signal loss with a 90 degree adapter. Thanks for the help



 
Last edited:
bobmarkert said:
Which is preferable, a tight bend radius like the pic below or accept the signal loss with a 90 degree adapter. Thanks for the help



Click to expand...

Although it seems you probably already have the adapter pictured, Steinair offers a crimp 90-degree fitting that will involve two fewer connections and the associated loss. Will it make a difference in the real world? Not sure I can answer that. But for $17.50 it's not bad insurance.

http://www.steinair.com/storedetail.cfm?productid=137
 
A 90 degree connector will be a predictable loss and long lasting so would be my preference. A tight radius that is at the cable min bend radius limits or beyond in conjunction with deterioration that may occur there over the years will be variable and could ultimately lead to performace isues. The tight bend changes the cable impedance and leakage if the dielectric and or shield becomes damaged.
 
Why are you not using the tray mounted 90 deg adapter supplied with the install kit?
The mfr considers it to have an acceptable amount of loss, and then you can remove the radio without having to access the back of the radio tray.
 
I have to agree with Stein and Bob,
Your already against the subpanel and vibration will cause the connection to get loose, do as they suggest and use a 90. And you wont't have any regrets.

Stein is great to work with and was more than willing to talk to me when I had issues. He does a great service to our home built community.
Jack
 
Kink!

Use an adapter or a 90 deg connector. The pictured bend will cause all sorts of problems over time. As my friends will quote me: "90% of the problems are cables or power supplies" Don't be a cable statistic!
 
bend radius for coax is.....

general bend radius would be 10x the dia of the coax. Most routing (ok, on my plane anyway) doesn't require even that small of a radius and it's only bent once.
That said, I would think that if it bothers you then go with what gives you the most peace of mind.
danny
 
bend radius

sorry I didn't state my source. Boeing has an electrical wiring document that deals with routing. Between the two diffrent references I found the minimum bend radius is 10x the diameter. Granted the machines are way different, the cable is still the same. Haven't looked into AC43.13 though. I wonder if it's up to date enough to cover rg400?
btw, I'm doing my antenna cables and the biggest problem seems to be hiding them....
danny
 
az_gila said:
The recommended minimum bend radius for RG-400 is 1 inch.

http://www.pasternack.com/images/ProductPDF/RG400-U.pdf

It looks like you are exceeding it.
Click to expand...

I'd agree with this for a bend in the middle of the cable, but here, it's going into a crimp connection which never seem to be too great. The cable inner insulator is PTFE/Teflon, which likes to cold-flow under load. The stress concentration at the bend to crimp interface can relax and loosen over time.

My recommendation still is to add the 90 deg adapter.
 
final choice

Thank you for all the replies. Here is what I decided. I wasn't happy with my wire bend, and did not want to accept the loss of a 90 degree adapter adding another joint so I went to the avionics shop on my field (KBJC). He sold me some 90 degree BNC and TNC connectors. These require soldering the center wire to the pin but it turned out to be easy. $11.95 for the BNC and $15 for the TNC's. Worth it because I don't expect any issues with these connectors in the future. Below are the "before and after" shots. I know I still need to move a few more wires to prevent chaffing damage in the future



 
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