Actually, IMD in the PA increases significantly as battery voltage drops! For example, during Field Day a few years ago someone kicked off the generator power to our SSB station which kept operating on the back-up battery. Sometime later the CW captain stopped by asking if we had changed anything. He could hear "splatter" from our 20m signal on his 20m rig. This was not the case earlier in the day.
I checked everything and discovered the AC power issue. I turned the outlet switch back to On and checked with the 20m CW operator. His reception had immediately cleaned up! He no longer heard anything from 20 SSB the rest of the (non-contest) event. BTW, we went on to take 4th place overall with just six transmitters (2012). When driving a KPA500, this is much less of an issue since the K3 runs typically under 30 Watts for 500 Watts from the KPA500. NC0B has spoken frequently, in less than glowing terms, about IMD issues in 12 VDC (nominal) PA's. I've seen a number of comments recently that some folks don't care if their radios' TX IMD is high. That attitude is exemplified in many DX pileups. I have raised my power supply's voltage in an effort to keep my TX IMD as low as possible based on my reading and empirical evidence related above. 73, Bill, K8TE Albuquerque DX Assn Message: 23 Date: Tue, 29 Dec 2015 15:57:18 +0000 From: John Macrae <[email protected]> To: Marc Veeneman <[email protected]>, Juliean Galak <[email protected]> Cc: "[email protected]" <[email protected]> Subject: Re: [Elecraft] Powering a K3s from a battery? Message-ID: <CAGfPUrh=j8ofirrxyxgibvqgj5x266kcbyjvescgd9jrnjg...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 I run /P on a 35aH lead acid battery. Whilst there is a noticeable voltage drop, I have worked dx till the battery voltage falls well below 11v without any noticeable effects on signal quality (I asked)! I have also run from a battery in the shack with a charger connected. No problem. Clearly the larger the battery, the less problems you will have. GL and 73 John, C6ATS On Tue, 29 Dec 2015 15:43 Marc Veeneman <[email protected]> wrote: > My K3/P3/VGA monitor are happy with power from > http://bioennodepot.com/lithium-iron-phosphate-lifepo4-batteries/bioenno-pow er-12v-40ah-lfp-battery-pvc-blf-1240w.html > > It's small enough to lie flat on a shelf with 3.5" clearance with a > footprint smaller than my iPad. > > My KX3/PX3/KXPA100 run on another identical battery. These have plenty of > capacity to power 100 watts CW for longer than I can stay active. They > start out at 13.2 volts and stay there for hours. I do use #10 AWG wire, > though, to minimize resistive loss. > -- > Marc W8SDG > > ______________________________________________________________ > 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 > Message delivered to [email protected] > ______________________________________________________________ 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 Message delivered to [email protected]
