[Elecraft] KX3 keyline questions

[Don Wilhelm]

Steve,

Are you measuring with the amplifier connected?  That could be a reason.
Put in a plug with nothing connected and remeasure.  Be careful with 
autoranging meters, they can fool you.  Make certain you know what your 
meter displays for infinite resistance - it should be the same as shown 
with the probes apart and connected to nothing.
Make certain you are measuring between the ring and shell of the plug. 
The tip is GPIO and its behavior is controlled in the KX3 menu.

You should read an infinite resistance in receive and near zero ohms in 
transmit.  Voltage measurements of an open drain FET do not have much 
meaning.  Make certain your test plug is fully seated in the jack.

73,
Don W3FPR

On 11/21/2020 4:12 PM, Steve Zabarnick wrote:
> I'm exploring using my KX3 with the QRP-Labs 50W Amplifier. In measuring
> the keyline output, I get zero volts to ground when in receive and about
> 0.5 volts in transmit. When measuring resistance across the keyline I get
> about 70 ohms in receive and 5K ohms in transmit.
> 
> Isn't the keyline supposed to be open in receive and grounded in transmit?
>