[Elecraft] K-2 5 volts on Mic Jack

[W3FPR - Don Wilhelm]

Howard,

If your SignalLink interface has large capacitors on its voltage input line,
the answer is YES - it will draw significantly more than 10 ma when you turn
the switch on.

YES it is likely that the SignalLink is causing the +5 volt rail on the
front panel and Control board to drop long enough the cycle the K2 through a
reset condition.  The microprocessor directly uses this same voltage, and if
it drops even momentarily, there is the possibility that the K2's 'brain'
can become scrambled.

It is possible that you could leave the SignalLink power switch turned on
and use the K2 power switch to turn everything on and off - but beware that
any electrolytics still will have to charge up at power on and that could
slow the rise time of the 5 volt supply which the K2 microprocessor uses for
a 'power up reset' signalling indication - if you find the K2 begins to do
strange things after the interface is installed, remove it and consider
powering the interface from its own separate power supply.

I would tend to believe that the K2 mic connector power was considered only
for powering such things as microphones and mic pre-amps which draw only
microamps.

RANT ON ----

While it is nice not to have to power each accessory separately, it is
unreasonable to expect that any transceiver will provide power output
capability for any and all accessories that may come along.  That is what a
main power supply and power connection devices such as the RigRunner are
for.  Each accessory worth its salt should provide for its own internal
power needs - which may be sourced from an adequate 12 volt supply (or
115/230 volt power lines).

RANT OFF ----

73,
Don W3FPR

> -----Original Message-----
>
>
> I have a strange one for the group.
> I use a TigerTronics SignaLink for PSK. Yesterday I
> set the jumpers up to use it on the K-2. The interface
> can get it's power from the mic jack. The manual
> states that the unit draws 10 ma and I've used it this
> way on my IC-735. When I tried power up the
> interface(powered through the mic jack) the K-2 would
> go to the Elecraft welcome display as if I just
> powered up the K-2 then switch back on feq. Is it
> possible that the interface has a momentary power draw
> that is causing the K-2 to reset for some reason?
> Could this cause a problem down line if I tried to
> power the interface through the jack?
> 73
> Howard Stephenson   K6IA
>
>