Foot Switch wiring question...

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Foot Switch wiring question...

Clay Autery
Hooking up a Linemaster Clipper Model No. 632-S to my K3s rear PTT RCA jack.

Obviously, the RCA is 2-conductor unbalanced and there is no issue about
which terminals to use on the foot switch for normally open switching.

BUT, I want to make sure the foot switch cable is never an issue for RFI
in or out.

Options:

1) Use one-third of the Component cable assembly I built a long time ago
with nice Canare RCA connectors and L5-CFB coax. (simply cut of one
connector and connect the center conductor to the NO terminal and the
braid to the C terminal) for a quick and free solution.  Kind of stiff
with solid center conductor.

2) Use unshielded twisted-pair 2-conductor (or shielded leaving shield
disconnected) cable. (Have to buy a an RCA connector.)

3) Use shielded 2-4 conductor mic cable (nice and flexible).  I think I
have some Canare Star Quad around somewhere (Still have to buy the RCA
connector).

My question is:

*Do I need to worry about shielding this cable?*  I've got a ground to
pick up the shield in the foot switch, but no place to pick up a chassis
ground cleanly in the back of the K3s...  I could terminate the shield
to the RCA housing at the radio end, but that's going to the connector
board...

Alternatively, I could pull the shield out of the cable near the RCA
cable plug at sufficient length to pick up the chassis ground screw on
the back of the chassis with a ring terminal (not clean, have to buy RCA
connector and MAYBE the cable if I can't find my spare Canare Star Quad
mic cable).

I'm going to use the re-purposed component cable described above for
now, but I don't really want to EVER have to worry about this control
cable giving me issues.  I know it's a small thing, but if I cover all
the small things as I go along, it'll be less work to isolate problems
if/when they crop up down the line.

Jim?

Thanks a bunch!

--
______________________
Clay Autery, KG5LKV
(318) 518-1389

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Re: Foot Switch wiring question...

Grant Youngman
I’ve never had any problem with RFI on my footswitch, running legal limit from not all that far away.  Any old shielded cable ought to do just fine — think Radio Shack quality junk.

Certainly no need for Canare in this application.


Grant NQ5T
K3 #2091, KX3 #8342




> On Mar 12, 2016, at 3:46 PM, Clay Autery <[hidden email]> wrote:
>
> Hooking up a Linemaster Clipper Model No. 632-S to my K3s rear PTT RCA jack.
>
> Obviously, the RCA is 2-conductor unbalanced and there is no issue about
> which terminals to use on the foot switch for normally open switching.
>
> BUT, I want to make sure the foot switch cable is never an issue for RFI
> in or out.
>
> Options:
>
> 1) Use one-third of the Component cable assembly I built a long time ago
> with nice Canare RCA connectors and L5-CFB coax. (simply cut of one
> connector and connect the center conductor to the NO terminal and the
> braid to the C terminal) for a quick and free solution.  Kind of stiff
> with solid center conductor.
>
> 2) Use unshielded twisted-pair 2-conductor (or shielded leaving shield
> disconnected) cable. (Have to buy a an RCA connector.)
>
> 3) Use shielded 2-4 conductor mic cable (nice and flexible).  I think I
> have some Canare Star Quad around somewhere (Still have to buy the RCA
> connector).
>
> My question is:
>
> *Do I need to worry about shielding this cable?*  I've got a ground to
> pick up the shield in the foot switch, but no place to pick up a chassis
> ground cleanly in the back of the K3s...  I could terminate the shield
> to the RCA housing at the radio end, but that's going to the connector
> board...
>
> Alternatively, I could pull the shield out of the cable near the RCA
> cable plug at sufficient length to pick up the chassis ground screw on
> the back of the chassis with a ring terminal (not clean, have to buy RCA
> connector and MAYBE the cable if I can't find my spare Canare Star Quad
> mic cable).
>
> I'm going to use the re-purposed component cable described above for
> now, but I don't really want to EVER have to worry about this control
> cable giving me issues.  I know it's a small thing, but if I cover all
> the small things as I go along, it'll be less work to isolate problems
> if/when they crop up down the line.
>
> Jim?
>
> Thanks a bunch!
>
> --
> ______________________
> Clay Autery, KG5LKV
> (318) 518-1389
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Re: Foot Switch wiring question...

Don Wilhelm-4
In reply to this post by Clay Autery
Clay,

Use twisted pair wire between the switch and the RCA Plug.  The tighter
the twist the better.
If you use that, there is no need for shielding.
If you do use a shield, connect it to the outside of the enclosure of
the K3S (the RCA jack is grounded, but not to the outside of the enclosure).

73,
Don W3FPR

On 3/12/2016 4:46 PM, Clay Autery wrote:
> Hooking up a Linemaster Clipper Model No. 632-S to my K3s rear PTT RCA jack.
>
> Obviously, the RCA is 2-conductor unbalanced and there is no issue about
> which terminals to use on the foot switch for normally open switching.
>
> BUT, I want to make sure the foot switch cable is never an issue for RFI
> in or out.
>
>

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Re: Foot Switch wiring question...

Clay Autery
In reply to this post by Grant Youngman
Well, I'm not BUYING any Canare cable...  just re-purposing 1/3 of a
component cable I made a long time ago (and haven't needed in a decade),
OR using some leftover Star Quad (if I can find it).  I happen to have
50 NEW, unused Canare RCA connectors in the size required for L5-CFB
cable (think slightly bigger than 1/4", but 75 Ohm).
I realize broadcast quality cable is overkill... simply trying to not
buy new stuff right now if I don't need to... but don't want to "get by
for now" and let a potential RFI candidate into the system.

The REAL question is should I worry about an isolated chassis to chassis
shield, or simply use a flexible coax, or a nice and flexible
twisted-pair mic cable without a separate shield?

______________________
Clay Autery, KG5LKV
MONTAC Enterprises
(318) 518-1389

On 3/12/2016 3:58 PM, GRANT YOUNGMAN wrote:

> I’ve never had any problem with RFI on my footswitch, running legal
> limit from not all that far away.  Any old shielded cable ought to do
> just fine — think Radio Shack quality junk.
>
> Certainly no need for Canare in this application.
>
>
> Grant NQ5T
> K3 #2091, KX3 #8342
>
>
>
>
>> On Mar 12, 2016, at 3:46 PM, Clay Autery <[hidden email]
>> <mailto:[hidden email]>> wrote:
>>
>> Hooking up a Linemaster Clipper Model No. 632-S to my K3s rear PTT
>> RCA jack.
>>
>> Obviously, the RCA is 2-conductor unbalanced and there is no issue about
>> which terminals to use on the foot switch for normally open switching.
>>
>> BUT, I want to make sure the foot switch cable is never an issue for RFI
>> in or out.
>>
>> Options:
>>
>> 1) Use one-third of the Component cable assembly I built a long time ago
>> with nice Canare RCA connectors and L5-CFB coax. (simply cut of one
>> connector and connect the center conductor to the NO terminal and the
>> braid to the C terminal) for a quick and free solution.  Kind of stiff
>> with solid center conductor.
>>
>> 2) Use unshielded twisted-pair 2-conductor (or shielded leaving shield
>> disconnected) cable. (Have to buy a an RCA connector.)
>>
>> 3) Use shielded 2-4 conductor mic cable (nice and flexible).  I think I
>> have some Canare Star Quad around somewhere (Still have to buy the RCA
>> connector).
>>
>> My question is:
>>
>> *Do I need to worry about shielding this cable?*  I've got a ground to
>> pick up the shield in the foot switch, but no place to pick up a chassis
>> ground cleanly in the back of the K3s...  I could terminate the shield
>> to the RCA housing at the radio end, but that's going to the connector
>> board...
>>
>> Alternatively, I could pull the shield out of the cable near the RCA
>> cable plug at sufficient length to pick up the chassis ground screw on
>> the back of the chassis with a ring terminal (not clean, have to buy RCA
>> connector and MAYBE the cable if I can't find my spare Canare Star Quad
>> mic cable).
>>
>> I'm going to use the re-purposed component cable described above for
>> now, but I don't really want to EVER have to worry about this control
>> cable giving me issues.  I know it's a small thing, but if I cover all
>> the small things as I go along, it'll be less work to isolate problems
>> if/when they crop up down the line.
>>
>> Jim?
>>
>> Thanks a bunch!
>>
>> --
>> ______________________
>> Clay Autery, KG5LKV
>> (318) 518-1389
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email] <mailto:[hidden email]>
>

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Re: Foot Switch wiring question...

N5GE
In reply to this post by Don Wilhelm-4
I agree.  I used twisted pair for a long run up the tower to a pesky
Davis WX Station.  It worked great!


On Sat, 12 Mar 2016 17:09:13 -0500, you wrote:

>Clay,
>
>Use twisted pair wire between the switch and the RCA Plug.  The tighter
>the twist the better.
>If you use that, there is no need for shielding.
>If you do use a shield, connect it to the outside of the enclosure of
>the K3S (the RCA jack is grounded, but not to the outside of the enclosure).
>
>73,
>Don W3FPR
ARS N5GE

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Amateur Radio Operator N5GE