I answered David and apparently did not click on "Reply All." A long time ago using the Elecraft Keying Circuit, I simply replaced the 2N2222 keying transistor with a MPSA42 which can handle max 300V (Vce) at 100 mA. It worked fine with my SB-220 which has ~110V on the key line.
73, Ken K3IU -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Don Wilhelm Sent: Tuesday, July 18, 2006 9:57 AM To: David Douglass; elecraft@mailman.qth.net Subject: RE: [Elecraft] Amp keying circuit K2 David, Best solution: Change the output transistor to a mosfet device which will be capable of handling the higher voltage. See the .pdf from Tom Hammond's website - http://www.n0ss.net/k2_basic_8r_line_t-r_adapter.pdf for the re-designed output device (HEXFET). It will require changing one of the resistors in the present keying circuit as well as the output device. Another solution would be to use the present amp keying circuit (and a power supply) to key a relay - use the relay contacts to key the amp. Depending on the speed of the relays, that may slow things down a bit and you will cause problems with QSK keying. 73, Don W3FPR > -----Original Message----- > > Thanks for all the responses to this - much appreciated. > > I'm afraid it was a simple case of me not reading the instructions on > the keying circuit. > > The FL-2100B pulls 20v on its keying input, whilst the circuit for the > K2 is only designed for 5-12v !! This is clearly written on the > instructions with the circuit, which I neglected to read. > > Does anyone have details of a simple circuit I can build, so I can use > this with my FL-2100B ?? > > Again, many thanks for the all the replies !! > > David, VK2NU > > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
