[Elecraft] Bug Contact Bounce in CW+ Mode

[Vic K2VCO]

I've often had trouble keying modern solid-state rigs cleanly with mechanical bugs. I've 
tried various electronic debouncing schemes, with more or less success.

The simplest solution is to use a reed relay -- radio shack has a 12-volt one that works 
perfectly with a 9-volt battery. The battery lasts for months.

Put an electrolytic capacitor across the coil to soak up the bounce pulses. I used 10 uf, 
I think. Without the capacitor the reed relay is fast enough to reproduce the bounces.

You'll have to readjust your bug, since the circuit will lengthen the dits.

Problem solved.

On 6/19/2010 6:45 PM, Paul Christensen wrote:
> I just dusted off my Vibroplex Champion and tried testing with the K3.  The
> reports of intermittent audible side-tone click are correct in CW+ mode,
> although the click can be heard on either dits or dahs, depending on the
> degree of contact bounce.  I was able to easily replicate the side-tone
> clicks by moving around both bug contacts.
>
> I am using K3 F/W 4.03.  First, I tested the bug by plugging it directly
> into the K3's rear panel "KEY" input to confirm the issue.  Next, I plugged
> the bug into my external keyer with a modified Schottky gate/2N7000
> combination.  Then, the output of the keyer was plugged into the K3's KEY
> jack.  The Schottky buffer functions as a contact de-bouncer and ensures
> that each contact results in the 2N7000 FET going to ground and no state in
> between ground and +Vcc provided by the K3's key input line.  The input
> buffer cleans the bug contacts, resulting in no audible side-tone click.
>
> As an alternate to the Schottky buffer, some bug users may want to try
> placing a tantalum or electrolytic cap (e.g., 0.1uF - 0.47uF) across the bug
> output terminals, observing correct polarity.  Tests awhile back showed this
> helped with contact bounce, but not the pseudo-diode condition created by
> contacts of dissimilar metals as earlier discussed by Joe, W4TV.
>
> I sure wouldn't want Elecraft to in any way compromise CW+ as it presently
> functions.  As Guy points out, it may be a byproduct of the new ultra-fast
> QSK and as such, other methods of contact de-bouncing can be used when using
> a bug or straight key.
>
> If an external keyer is used with the K3, the first thing I would try is to
> plug the bug into the keyer and set it for "bug mode" and use its internal
> contact buffering capabilities to ensure that the K3 sees a clean On/Off
> state for every contact closure.  Some keyers utilize a second input just
> for straight keys and bugs and don't require the operator to change the
> keying mode through the keyer's menu.
>
> Anyway, these methods may be worth a try, starting with a cap or an external
> keyer.  If the problem persists, it may require a more robust de-bouncer
> like the Shottky gate type I'm using.
>
> Paul, W9AC

-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/