[Elecraft] Vibroplex Bug

[Guy Olinger K2AV]

Need to remember that in the days when bugs were king, the typical
voltage being keyed was between a cathode(s) and ground (often a
couple hundred volts at several hundred ma) or bias voltage (75, 105,
150 volts). Turn off the lights and key the bug keying an 807 rig, and
you could see the sparks.  Stuff of the time was never designed for 12
volts at 7 ma or the like. Even with the higher voltages and currents
had problems with contact bounce and resistance.

That was why when keyers started showing up, the sealed mercury-wetted
relays surplus from somewhere in the Bell System were all the rage.
No contact bounce or contact resistance problems.

One could really get tossed across the room by touching the "hot'
parts of the key.

73, Guy.

On Sun, Aug 23, 2009 at 7:10 PM, Ron D'Eau Claire<ron at cobi.biz> wrote:
> The problem I dealt with is not contact bounce, but contacts that do not
> make a low enough resistance connection to trigger the logic properly. It
> sounded like that was Werner's problem too.
>
> It's easy to see the contact resistance issue using a scope on the key line.
> The key voltage simply isn't being pulled down far enough to reliably key
> the rig unless the contacts are *very* clean, and without adequate current
> flowing through them to maintain a self-cleaning action, they quickly
> oxidize again without help - or some other way to key the rig like Vic's