On 9/17/2010 11:49 AM, Barry wrote: > I presume, historically, it was so there would be enough spacing to > prevent arcing for the 300VDC on the keying line, etc. Nowadays, most > headphones come with 1/8 inch plus, paddles/keyers are low voltage, etc.
I've wondered that myself. The phone and key jacks on my K3 and FT-847 are all 1/4" as was the key jack on my S-Line and on KWM-2A's. Mic jack on my S-Line was a 2-ckt telephone jack [smaller than 1/4"] which I swapped out for a 1/4". In fact, my K2 and KX1 are the only rigs I can name that don't/didn't have 1/4" key jacks. I guess some things just stick around whether there's a reason or not. Why didn't RCA phono plugs show up on headphones, they became ubiquitous for other audio lines? Still are to look at the back of our TV and DVR. Re Key Voltage: When I first started at the coastal marine station while in high school, the keying lines were 120VDC on metallic pairs to the TX site. You quickly learned to put the shoe from your bug right side up into the straight key on the desk and push your bug around the desk with the eraser on the end of your pencil. They switched to 48VDC which you could still feel but a much smaller jolt. Cathode keyed rigs were also good for a moderate knock if you grabbed the key behind the knob. 73, Fred K6DGW - Northern California Contest Club - CU in the 2010 Cal QSO Party 2-3 Oct 2010 - www.cqp.org ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
