What to do with Shielding on VP-X to Skyview?

larrynew · #1 01-02-2013, 11:16 AM

I'm running the wires with a dual Skyview and VP-X Pro install. When making the serial connection between the VP-X and Skyview, VP says to use 3 conductor shielded wire. What do I do with the shielding? The serial connection is TX, RX and GND to and from both. Do I add the shielding to the GND connection on both ends?

Thanks,

RV7Ron · #2 01-02-2013, 11:29 AM

A great question Larry...I am at the same point and am anxious to see what the 'VAF brain trust' says....

rleffler · #3 01-02-2013, 11:57 AM

Quote:

Originally Posted by RV7Ron

A great question Larry...I am at the same point and am anxious to see what the 'VAF brain trust' says....

Shielding always is only terminated at one end. (well, almost always, but the exeptions are few) When you terminate at both ends, you are most likely introducing a ground loop, which may cause noise on the circuit. The noise may not be of enough intensity to impact what ever data is on the serial circuit, but it will most likely introduce noise into your audio system.

Dynon Support posted a large reponse on this subject in another thread. You may want to do a search and read what they said.

bob

larrynew · #4 01-02-2013, 12:24 PM

Quote:

Originally Posted by rleffler

Dynon Support posted a large reponse on this subject in another thread. You may want to do a search and read what they said.

Thanks Bob. I did go back and re-read that post. Lots of good educational information about shielding on the exact serial line I'm working on. My summary: most recommend shielding, can't hurt.

But my question is now more specific about HOW to connect shield to ground. First, I'll only connect the shield to ground on one end. Then, I plan on splicing the shield into the serial GND line that goes into the VP-X and cross my fingers. Bad idea?

rleffler · #5 01-02-2013, 01:42 PM

Quote:

Originally Posted by larrynew

Thanks Bob. I did go back and re-read that post. Lots of good educational information about shielding on the exact serial line I'm working on. My summary: most recommend shielding, can't hurt.

But my question is now more specific about HOW to connect shield to ground. First, I'll only connect the shield to ground on one end. Then, I plan on splicing the shield into the serial GND line that goes into the VP-X and cross my fingers. Bad idea?

You want a solder sleeve with a pig tail. You can buy them with a pigtail or add your own.

You can get them from SteinAir, ACS, and even HomeDepot (but they don't always stock ones small enough for our use)

As for where to connect the shield to ground, you'll start a debate like the primer wars. For this particular case, ground at either end of the wire is probably ok.

If you haven't read the grounding chapter in Bob Nuckoll's AeroElectric Connection, I would highly recommend it. It's a good reference manual on these types of issues.

bob

Jeff A · #6 01-02-2013, 01:51 PM

FWIW, I used three conductor shielded wire between the VP-X and Skyview without connecting the shield at either end, and it works flawlessly.

jrs14855 · #7 01-02-2013, 01:57 PM

google "aircraft headset jack installation" , it will take you to some aeroelectric information and also a video. Generic info-not Skyview. but it shows various ways of grounding the shield. Solder sleeves are nice but not essential.

larrynew · #8 01-02-2013, 02:24 PM

Quote:

Originally Posted by rleffler

As for where to connect the shield to ground, you'll start a debate like the primer wars. For this particular case, ground at either end of the wire is probably ok.

Thanks for the help, guys. I should have worded it better. WHERE, not HOW should I ground the shield on the VP-X. There's no convenient connector on the VP-X like on the backshell of a radio. Is it acceptable to pigtail the shield into the GND connection like in this picture?

rleffler · #9 01-02-2013, 03:08 PM

Any of those ground points should work.

az_gila · #10 01-02-2013, 05:07 PM

Quote:

Originally Posted by larrynew

Thanks for the help, guys. I should have worded it better. WHERE, not HOW should I ground the shield on the VP-X. There's no convenient connector on the VP-X like on the backshell of a radio. Is it acceptable to pigtail the shield into the GND connection like in this picture?

Yes....

....more words added to keep the sw happy...