[Johnson] Rotary switch issue

[John]

Hi Bob

Can you see flex along the shaft that isn't allowing the farthest wafer to
go "home" to its correct orientation?  I suppose this could come both from
the shaft itself AND/OR from the stack of switches itself (which must be in
synch with the detents on the front) which might flex too.

If you hold the back wafer of the switch stack so that *it* cannot flex and
turn the switch, does it find the correct position that way?

All sources of friction in the back wafers should be resolved, but I'm sure
you've done that already.

John K5MO




On Sun, Feb 12, 2023 at 2:32 PM Robert Nickels <ranickels at gmail.com> wrote:

> This is a problem on the Pacemaker I'm working on but since the same
> rotary switches were used on all the EFJ transmitters I thought I'd ask
> to see if anyone else has run into it.
>
> The problem is in the multi-deck bandswitch where a long phenolic shaft
> runs from the front panel knob through all the wafers. What is happening
> is, in the 80 meter position which is at the extreme CCW rotation, the
> wipers on the rear-most wafers aren't reliably making contact with the
> last set of (80M) switch contact fingers.    It's as if the shaft just
> isn't being rotated far enough CCW.   The rotation increments are fixed
> by the detent mechanism on the front end of the shaft and all the wafers
> are supposed to track, but it seems the two furthest away aren't,
> quite.   All the wafers are held in place by spacers so I don't see much
> chance for error or wear.
>
> It's annoying because those wafers connect exciter tuning capacitor
> gangs, and when they don't make contact the exciter doesn't track and
> output power diminishes.  Any suggestions would be welcome!
>
> 73, Bob W9RAN
>
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