[Elecraft] Problems using a QRO amp with the K3

[Paul Ferguson]

I have a QRO Technologies HF-2000 amp. I am keying it with a K3 thru the amp's
"+15V Key Xmit" input port, but I have a homebrew transistor circuit between 
the K3 and the amp to supply +12V to this input.

The other amp keying port is called "Key Xmit". It needs only a contact closure
able to handle 80ma. However the open circuit voltage measured at this port is
about 150V. When I had a different transceiver, I was concerned about the high
open circuit voltage. I built the interface to allow use the "+15V Key Xmit" 
port and avoid any damage to the transceiver relay.

Maybe this high open circuit voltage is the cause of the problem with the K3 
trying to key the amp? 

73,
Paul
K5ESW


> 
> Anyone out there using a QRO with the K3?  I can't seem to get the amp
> working with the K3.  I have previously used the amp with the 480HX, 1000MP and
> 706 MIIG.  I am using the key out circuit on the back which does activate the
> relay in the amp but when I release the ptt, the amp stays in transmit and will
> not release.  Before I did use the ALC circuit with the amp but I have been told
> I do not need to use an ALC circuit with the K3. Do I need a separate t/r relay
> between the radio and the amp?  Is there some other menu item I have overlooked?
>  Any help will be appreciated.
> 
> 73, Richard
> N4WDU
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