Hello Gary, and congratulations! Opening up the K3 again is not nearly as traumatic as you might think.
The POWER control will *ask* for more than the rig can deliver. It's spec'd at 100 watts, and that's what is guaranteed. The K3 can make a bit more than 100 watts on most bands, but that's all it's spec'd to do. When you set the POWER control for a specific output, it tries to adjust the transmitter circuits for that output, but can't do it if it's out of their range. That's what is happening to you at 120 watts. The absolute maximum power will vary by band and to some extent from rig to rig. But since 120 watts is a whole 0.8 dB more than 100 watts, it's not significant on the air. You're probably crowding that 20 amp supply at 100 watts on some bands. The efficiency (and so the current required for a given output power) varies from band to band. I'm running a K3 with a 20 amp supply, but I'm near the limit on some bands at right on 20 amps for 100 watts out, if the SWR is quite low. (Higher SWR's reduce the efficiency so the current goes up!) I don't know whether your supply has a crowbar circuit in it, but my Astron does. It lets me know if I push too hard by simply shutting down. I have to cycle the power supply mains switch to reset it, then turn the K3 on again. Ron AC7AC -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Gary Smith Sent: Saturday, December 20, 2008 9:04 PM To: elecraft@mailman.qth.net Subject: [Elecraft] K3 Power out Firstly Got the K3 assembled. The transverter board was back ordered and so is the subreceiver so I will be re entering the K3 and adding to it at least twice over the next few months. I'm not looking forward to the disassembly & re-assembly but doing the kit sure gave me a great appreciation for the detail and function this marvelous radio has. Absolutely amazing. Kudos Wane & Eric, you surely have an amazing way of looking at things. Most effective and clear. With that there are a few questions but in the spirit of one at a time; The power supply I have been using in the setup is a Heathkit Power supply which was made for one of their last Transceivers. It's a HP- 1144 and offers 20 Amps out. After calibrating the K3 I tried getting 120 watts out to the dummy load but after the 50 watt calibration, when I held tune down to see how it read. I only got 102-105W out, not 120, though I set he power out at 120W. I'm wondering if the Heath power supply is lacking and that's the reason for the lower maximum output? It seemed to work well as a backup for the Omni V & corsair. Idears? Thanks Gary (One year older as of yesterday...) _______________________________________________ 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
