[Elecraft] queer behaviour !

[Tom W8JI]

The SB230, like the SB200 and a few other amplifiers, has negative high 
voltage keying line voltage. The voltage is well over 100 volts negative. It 
is not compatible with the K3 and many other radios  that are designed for 
the standard positive voltage lines.

It can actually damage many radios if the relay line of amplifiers like that 
are plugged directly into radios. It is even bad for radios that have relays 
to key amplifiers, because over time it can damage relay contacts even.

I would use some type of solid state relay isolation device.

> A good friend of mine, F6CVM, has a K3 as well as an Icom transceiver. He
> uses an old Heath SB 230 as an amplifier.
> When he connects Icom/SB 230, no problem.
> But if he connects K3/SB 230, as soon as he plugs the cinch into the K3 
> key
> out output , (with no drive), the  amplifier sets on the transmit position 
> !