It’s not often you actually have a recorded history of setting up an antenna. I recently had the accidental good fortune to do just that while making antenna adjustments on the final day of a visit to the Grayland Motel, near [oddly enough] Grayland, WA.
The more I listen to the Perseus wav file the more struck I am by how well this antenna works. Without getting wordy and showing how little I know about antenna theory and radio wave propagation, let me just describe what the file is. It’s a Perseus wav file of the whole MW band, 30 seconds long, about 450MB in size. It runs from about 15 seconds before 1500utc to about 15 seconds after — the ‘switch’ from unterminated to terminated occurs at clock reading 1500:55 UTC. Short reason why is that I ‘fake out’ the clock on the CPU to start Mestor TOH recordings at :58 instead of the default :59. The antenna is a 160’ DKAZ ‘aimed’ at about 290 deg. with #20 wire terminated with a Vactrol set to about 900 Ohms but variable with a pot in the ‘shack’ [Room 15 at the Grayland Motel]. The pattern of an unterminated DKAZ looks like a fat peanut along the axis of the antenna - bi-directional with some attenuation off the sides. A properly terminated DKAZ looks like a cardioid that’s flat in the back. With the antenna ‘pointing’ at 290 deg. off-the-back is about 110 deg. Nulls of 30 dB or better on easy-to-null groundwave, straight off-the-back stuff indicate a ‘healthy’ DKAZ. During skywave conditions things get a little more dicey as the signals are coming in at a variety of arrival angles. At 1500utc in February there is still plenty of skywave - from all directions - coming into Grayland. — Here’s a few ‘not to miss’ items to check out if you download the wav file: 780 - KKOH, Reno [155 deg from Grayland], -54 dB unterm. -> -74 dB term. [20 dB null] 750 - KXTG, Portland [140 deg], -41 dB unterm. -> -67 dB term. [26 dB] 730 - KNFL, Boise [117 deg], -47 dB unterm. -> GONE - totally dominated by "Vancouver’s traffic station!" Did I mention the DKAZ is wide-band? I use the 160’ version to get better low-band performance, shorter overall lengths work pretty well too though with some reduction in low-band performance. To illustrate … 1700 - XEPE Tecate, Mexico [156 deg], -57 dB unterm. -> GONE - het from 1701 low-power Aussie 570 - KVI Seattle [61 deg], -51 dB unterm. -> -75 term. [24 dB], note big het from Japan on 567 — If you’re interested in hearing what this sounds/looks like, you can grab the file this way: - go to http://america.fortw.com:8000 - click on Anonymous login - look for and click on the 2nd file down from the top - a window will pop up, click on Download File Enjoy! P.S. - I believe you can download and use Perseus software to play wav files without owning a Perseus receiver. There may also be other software out there these days that will play Perseus files. Bill Whitacre Alexandria, VA _______________________________________________ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
