[Elecraft] key down voltage drop

[W3FPR - Don Wilhelm]

I would suggest that the problem is inside the power supply - perhaps 
something as simple as a poor connection on the inside of the output 
terminals.  Even the drop you are seeing with the TS-570 seems excessive to 
me.

We don't know the actual current being drawn, but it may be quite different 
with the 100 watt TS-570 and the K2 (the K2 may actually draw more under 
these conditions).  I am not familiar with the TS-570, but many other 
transceivers will simply produce less power with a lowered voltage, but the 
K2 will attempt to draw more and more current with reduced voltage levels in 
an attempt to produce the power output that has been requested - this is 
done by the K2 internal ALC function.  That COULD explain part of the 
voltage with the K2 at 100 watts, but it does not explain the 12.1 volts 
with the K2 at QRP levels - something very strange is present here, and 
IMHO, the 'cure' will be found in the power supply.

73,
Don W3FPR

----- Original Message ----- 
From: "Dan Barker" <dbarker at visioncomm.net>


> That is very odd indeed.
>
> You should measure at the other end of the wires, to see what the radio is
> seeing, but I'm afraid that would make it even worse.
>
> Can you measure the current being drawn? That would be an interesting
> figure.
>
> ---------------------------------------------------------------------------
>
> k6xr Sent: Thursday, September 16, 2004 2:44 PM
>
> Hello Dan and thanks for your thoughts.
>
> I installed both the 570 and the k2/qrp and k2/100 on a astron AS35a power
> supply.
> I connected a voltmeter across the power supply terminals and keyed each 
> rig
> on 20 meters at 1.0.1 swr at 100 watts output.
> power supply voltage unloaded measures 13.8 volts.
>
> ts-570 drops voltage down to 12.4 volts
> k2/100 drops voltage down to 10.8 volts.
>
> k2/qrp at 15 watts drops down to 12.1 volts.
>
> the reason for all this is that I kept getting 558 557 598 signal reports
> and decided to see if I had a voltage problem.
>