Key-down tuning for QRO is a no-no, as is RTTY. They spec the power supply at 22 amps -->> 25% duty cycle <<-- or 5 amps continuous. 12.5 volts times 5 amps is 62.5 watts. If one figures in the usual 50% efficiency of transistor rigs, that's 31 watts brick on key, a figure that will be need to set as a tuning power limit in an auto-tuner rig. Probably better to say 25 watts continuous and enough to drive an amp that drives with 50-60 watts, IF the amp can be tuned at half power. Otherwise, tuning the amp would require a pulser or string of dits.
For a suitcase situation it would be ideal, just back the power off. What I don't understand is why they didn't double up on the cap, upsize a few things and get it to 22 amps 50% duty cycle. But in its current miniature version, I've toyed with the idea of deconstructing the power supply and reconstructing it inside an EC2 with a KPA100 as a companion to my going-to-stay-that-way 10W battery K2. 73, Guy K2 #1239 K3 #1239 On Mon, Jan 25, 2010 at 7:55 AM, Douglas Furton <[email protected]> wrote: > I've been running my CW only K2 using the "hybrid" power supply designed by > Fred (K3GQ) at Gamma Research. This tiny power supply packs a big punch > because it is loaded with about 5 farads of capacitance. The capacitors > provide the high current surges needed during the high-power portions of the > duty cycle, but recharge during low-power portions of the duty cycle. You > can read more about this thing at <http://www.gammaresearch.net/hps-1a.html>. > In all ways, I've found this power supply to be an excellent piece of work > (and I haven't noticed any RF hash). > > Now that I've added the KPA100/KAT100, in a separate EC2 enclosure, I'd like > to continue to run this power supply. But I'm wondering if anyone thinks > this is a bad idea. > > The potential problem lies in the fact that the power supply is in a sense > not well regulated. While it never provides a voltage > 13.6 V, the voltage > sags on TX as the capacitors discharge. Fred has designed this power supply > so that it can power most rigs at 100W (CW or SSB, but my work is only CW) > before the voltage sags below ~12V for normal CW/SSB duty cycles. > > I've measured the voltage sag at the output of the power supply with an > oscilloscope and find that when I send CW at 15 WPM into a dummy load at 100W > with my K2, the power supply sags as low as about 11.9 volts on TX. Of > course, the voltage recovers quickly between the dahs and dits as the caps > recharge, but again, never even momentarily goes below ~11.9 volts. Also, as > I noted above, the power supply never provides a voltage > 13.6 volts. > > I could acquire and attach an o-scope trace, if that would help anyone make > up their mind. > > I'm wondering how this rapid supply voltage variation might affect the K2? > I've not noticed any problems, but I'm not that bright. > > Doug > K8EXB > > ____________________________________________________________ > Receive Notifications of Incoming Messages > Easily monitor multiple email accounts & access them with a click. > Visit http://www.inbox.com/notifier and check it out! > ______________________________________________________________ > 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 > ______________________________________________________________ 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
