[Elecraft] Foot Switch wiring question...

[Clay Autery]

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 <cautery at montac.com
>> <mailto:cautery at montac.com>> 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
>>
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