[Elecraft] K2/100 Keying a Drake L-4B

[Don Wilhelm]

Ariel (and all),

I don't know the specifics of that amplifier, but one can make a quick 
measurement to find the answer for yourself.
Turn on the amplifier and measure the voltage at the amp's Keying input 
with your DMM.  Is it positive or negative?  How large is the voltage?

If you are concerned about the keying current, set the DMM to measure 
current.  The amplifier will key, and the meter will indicate the 
current that is developed.

73,
Don W3FPR

On 8/4/2013 7:56 AM, Ariel Jacala wrote:
> Hi Elecrafters,
> I am ready to key my Drake L-4B using my K2/100 but I read from a previous post:
> "If you already have the KPA100, look on the rear panel and you will see an RCA jack marked "PA KEY OUT" between the ground connection and the power connector - this will allow you to key your external amplifier directly - but only if your amplifier has a positive voltage for its keying line.  If  your amplifier uses a negative voltage keying circuit (like the Collins 30L-1 and some others) you will need to construct an external circuit to key the amp.  73 --don n4hh K2/100 #2028"
> Does the Drake use a negative voltage for the keying (line)?
> If it does what modification do I need.   I installed the Soft-key mod made by Harbach. I am not sure whether that converts the Drake to positive voltage keying.
> Any help is appreciated.
> Ariel 		 	   		
>