And Yet Another "Home-Brewed" item. 3 Wire Shielded cable.

["Dart67"]

In the process of doing my 440/512 engine rebuild and redoing some of the EFI/Coil Near Plug wiring, I need a 6 foot length of 3 wire shielded cable for my cam position sensor.

I thought I had some here. Nope... Needed to get the wiring and harness finished so did not want to order and wait.

SO, I made my own.

I had the correct 3 colored 18 gauge wire.

What could I use for the shield?

Lets see.... Being a Ham Radio operator, I have some short random lengths of RG8 coax laying around.

Found a piece close to the length I needed and stripped off the outer rubber coating and slid the woven copper shield off the center conductor.

Then taped the 3 wires together and pushed them through the salvaged copper shield. Should work better than the minimal shielding that comes on most shielded cable.

 

[67Dart273]

Been there done that. You realize you only ground one end? At the computer end. "Faraday shield." You can also use other cables that are not shielded, with extra pairs, and ground the unused pairs at one end. May not be quite as effective, but often works.

First time I did that, was working out of town installing 911 gear. Motorola had made a change in the remote radio control console. The under desk headset connector was not shielded, they are balanced pairs. But it was picking up hash from the very large, very powerful CRTs used back then for the CAD (Computer Aided Dispatch) and the other for the ANI/ ALI for 911 (Auto Number, Auto Location Information). So I did the same thing grounded one end to the rear of the console interface, and just like that, gone. The boss was impressed when I told him about it.

I am 77. First licensed in 65, Jr in high school, got my general after graduating.

This was our ham club at Treasure Island, Navy electronics tech "A" school. I recently heard we have just lost another two of us.

There are three websites about the old club

K6NCG - Treasure Island Radio Amateur Club 1969-1970

K6NCG Amateur Radio Station - Treasure Island, CA

K6NCG
Me, 1968, 20 years old, working at the top of the 120ft tower

 

[gzig5]

In the process of doing my 440/512 engine rebuild and redoing some of the EFI/Coil Near Plug wiring, I need a 6 foot length of 3 wire shielded cable for my cam position sensor.

I thought I had some here. Nope... Needed to get the wiring and harness finished so did not want to order and wait.

SO, I made my own.

I had the correct 3 colored 18 gauge wire.

What could I use for the shield?

Lets see.... Being a Ham Radio operator, I have some short random lengths of RG8 coax laying around.

Found a piece close to the length I needed and stripped off the outer rubber coating and slid the woven copper shield off the center conductor.

Then taped the 3 wires together and pushed them through the salvaged copper shield. Should work better than the minimal shielding that comes on most shielded cable.

View attachment 1716464826

Clever solution to the lack of the cable. I am not being critical, and only trying to provide some additional information regarding shielding and electrical noise. You may have wanted to put a twist in the three conductors before pulling them through the shield. I worked in design, quality, and field service for a major manufacturer of industrial automation, and I was focused on our servo drives and motors. Electrical "noise" was a constant challenge with the high switching frequency of the servos and long cables and auxiliary conductors that run between the drive and motor, and something we extended a lot of effort on. One of the worse things you can do for coupling HF noise injection into a conductor is to run them parallel, with no twist in the conductors. May not be an issue for your application, but the more reliable way to go about it would be to braid the three conductors on a 3-6" twist, then pull them into the shield. You'll also want to limit the amount of unshielded conductors on each end, and route the cable away from any other potential sources like plug wires and or power wiring. If you do have to cross a potential source, arrange the wires at a 90 degree angle to each other. This minimizes noise coupling from source to victim.
Probably more than anyone cares to know, but chasing noise gremlins can be very frustrating. I've spent a good portion of my career on the topic.
This is a link to a document we came up with to help our customers design their servo drive installations with the best chance of success. It isn't all applicable, but a lot of the information can help avoid issues on installation of aftermarket engine controls, A/V units, and ignitions. I worked on some of the tests in Appendix A, and hold a patent related to circular bonding of motor power cables.

https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/gmc-rm001_-en-p.pdf

Again, a clever solution to the problem that very well perform as intended. But it does have some vulnerabilities that may be exposed if something in the system changes or it's tried in another application.

 

["Dart67"]

Clever solution to the lack of the cable. I am not being critical, and only trying to provide some additional information regarding shielding and electrical noise. You may have wanted to put a twist in the three conductors before pulling them through the shield. I worked in design, quality, and field service for a major manufacturer of industrial automation, and I was focused on our servo drives and motors. Electrical "noise" was a constant challenge with the high switching frequency of the servos and long cables and auxiliary conductors that run between the drive and motor, and something we extended a lot of effort on. One of the worse things you can do for coupling HF noise injection into a conductor is to run them parallel, with no twist in the conductors. May not be an issue for your application, but the more reliable way to go about it would be to braid the three conductors on a 3-6" twist, then pull them into the shield. You'll also want to limit the amount of unshielded conductors on each end, and route the cable away from any other potential sources like plug wires and or power wiring. If you do have to cross a potential source, arrange the wires at a 90 degree angle to each other. This minimizes noise coupling from source to victim.
Probably more than anyone cares to know, but chasing noise gremlins can be very frustrating. I've spent a good portion of my career on the topic.
This is a link to a document we came up with to help our customers design their servo drive installations with the best chance of success. It isn't all applicable, but a lot of the information can help avoid issues on installation of aftermarket engine controls, A/V units, and ignitions. I worked on some of the tests in Appendix A, and hold a patent related to circular bonding of motor power cables.

https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/gmc-rm001_-en-p.pdf

Again, a clever solution to the problem that very well perform as intended. But it does have some vulnerabilities that may be exposed if something in the system changes or it's tried in another application.

Thanks for the input....

Having worked as a Business / Data technician for almost 40 years and being a HAM Radio operator, I am well aware of the need to twist the wires to help reduce interference and noise.

Thank again.

 

["Dart67"]

Been there done that. You realize you only ground one end? At the computer end. "Faraday shield." You can also use other cables that are not shielded, with extra pairs, and ground the unused pairs at one end. May not be quite as effective, but often works.

First time I did that, was working out of town installing 911 gear. Motorola had made a change in the remote radio control console. The under desk headset connector was not shielded, they are balanced pairs. But it was picking up hash from the very large, very powerful CRTs used back then for the CAD (Computer Aided Dispatch) and the other for the ANI/ ALI for 911 (Auto Number, Auto Location Information). So I did the same thing grounded one end to the rear of the console interface, and just like that, gone. The boss was impressed when I told him about it.

I am 77. First licensed in 65, Jr in high school, got my general after graduating.

This was our ham club at Treasure Island, Navy electronics tech "A" school. I recently heard we have just lost another two of us.

There are three websites about the old club

K6NCG - Treasure Island Radio Amateur Club 1969-1970

K6NCG Amateur Radio Station - Treasure Island, CA

K6NCG
Me, 1968, 20 years old, working at the top of the 120ft tower

Del,

Thanks for your input and reminder as to which end to connect to ground. I worked as a Business / Data technician at GTE/Verizon for almost 40 years, so I know a little about noise on circuits.

As far as the HAM Radio, I got my 1st Novice ticket in 1976. WN9RLY... I have hearing problems so the Morse code was a real struggle for me. I could barely get the 5 words per minute required for the Novice. Let alone the 13 word per minute for a General ticket. I ended up having 3 different Novice calls before they came out with the Tech Plus ticket. I could ALWAYS pass the General theory part of the test. Just not the code. The Tech Plus required 5 words per minute and passing the General theory. Which I did in 1986 as N9QEP. After moving from Illinois to Arkansas, I finally in 2010 took the General test and passed. If I had studied for the Extra I think I could have gotten it. I took that test the same day and got 50% without any study at all. My call is now W5HMB. My initials. HMB Herbert Mitchell Beer. When I make a call, I identify as Whiskey 5 Herb's MOPAR Barn.

Here is the link to our local club. HSVARC – Hot Springs Village Amateur Radio Club

Check into our net using the Echo Link some Tuesday evening at 7PM central time.

Herb aka "Dart67" W5HMB

 

[gzig5]

Thanks for the input....

Having worked as a Business / Data technician for almost 40 years and being a HAM Radio operator, I am well aware of the need to twist the wires to help reduce interference and noise.

Thank again.

I appreciate your experience. A majority of folks don't have that, so I hope that my input would help someone that doesn't.
Keep sharing your projects.

 

["Dart67"]

I appreciate your experience. A majority of folks don't have that, so I hope that my input would help someone that doesn't.
Keep sharing your projects.

I love sharing what I do. More for the reason you just stated "that my input would help someone". I am not in any way tiring to show off or brag, etc. Just tiring to help and pass on ideas and different ways of getting something done.

That is the Whole idea behind this and many other forums. Helping and Sharing.

If folks do not like my post, they can simple pass by them and not look at them.....

This forum and its members have been a wealth of information and help to me for many years.

Thank You All......