A simple way to find out is turn the amplifier on and measure the voltage on the keying input on the amplifier, noting the voltage and its polarity. Next switch your multimeter to measure current and connect it to the same place on the amplifier. The amplifier should key and you will see how much current needs to be switched by the radio. This procedure should work with any amplifier.
73 - Mike WA8BXN -------Original Message------- From: Ariel Jacala Date: 08/04/13 07:57:01 To: elecraft reflector Subject: [Elecraft] K2/100 Keying a Drake L-4B 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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
