Thanks for the info, Ed. I'm going to have to figure out my own antenna for this band.
Wayne N6KR ---- http://www.elecraft.com > On Sep 17, 2017, at 12:01 PM, Edward R Cole <kl...@acsalaska.net> wrote: > > Thanks Wayne. > > I have been using my K3 (SN 4043) purchased in 2010 on 495 to 502 KHz from > 2012 as part of the ARRL Experimental 500-KHz Group using experimental > license WD2XSH/45. Primarily using std CW or WSPR at about 4w ERP. Our > experimental license specified using power up to 20w ERP so one had to > calculate from EIRP. > > New ham regs now use EIRP which is typically shown if modeling an antenna > using EZNEC. I modeled my 43-foot high by 122-foot long inverted-L which > results in impedance at 503-KHz of Z = 0.83 - j886.5. I measured the antenna > using my modified MFJ-269B at 18 - j0 after adjusting the base loading coil > for resonance. > > Then get total radiated power from TPR = 0.83/18 * 100 = 4.6w (note my > amplifier is running 100w into 50-ohm load). > From EZNEC-5 antenna gain = 1.48 , EIRP = 4.6 * 1.48 = 6.8w > ERP = 6.8/1.64 = 4.15w. Thus my antenna efficiency is only 4%. > > My unmodified K3 will only operate down to 490-KHz but I have the new synth > board and mod kit for the KBPF3 to install which will extend operation to the > new 630m band (472-479 KHz). I was able to get 1mw output with my unmodified > K3 in TEST which I drove a modified NDB transmitter to 100w. The NDB is an > aircraft CW beacon with dual xtal LO separated by 400-Hz. By CW keying that > shift it produced a mcw signal. I removed he LO and simply capacitively > couple about 0.1 mw to fully drive the three stage amplifier. I was able to > pick up the NDB surplus for $40 which is self-contained with 55v PS. I > expect them to quickly be snatched up by 630 ops. > > I home made a 10-inch by 11-inch base coil wound 1/4 inch spacing on a > plastic form to provide loading. I have two taps which are moved between > winter and summer soil conditions which shift the ground resistance enough to > shift resonant frequency. I got about 5-Hz SWR bandwidth. > > Previous to the new mods, I ran a SDR-IQ receiver and only transmitted with > the K3. I have picked up the CW signal from an Oregon station and my signal > has been detected as far as Buffalo, NY. > > AFAIK only two commercial radio will operate on our new ham band: K3s (and > mod K3) or theTS590. This opens a market for entrepreneurs to provide > preamps, amplifiers and transverters. Puts Elecraft ahead of the "crowd", > again! > > NOTE: FCC requires pre-registering with UTC before operating on 630m. Its a > 30-day process. I'm waiting for my approval. > > > > 73, Ed - KL7UW > http://www.kl7uw.com > Dubus-NA Business mail: > dubus...@gmail.com > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to n...@elecraft.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
