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- Subject: Re: [CapeDX] Switch from unterminated to terminated DKAZ caught on wav file!
- From: Mark Connelly <markwa1ion@xxxxxxx>
- Date: Mon, 7 Mar 2016 10:35:24 -0500
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In a similar vein on directional antennas, I actually made up daytime stereo audio recordings with a Flag antenna having one receiver (Drake R8A) listening on its northeast side and another R8A receiving at the same time on the southwest side.
These were done in 2004 and 2005 at my former location of Billerica, MA (NW suburbs of Boston).
1230 kHz: northeast side = WESX Salem, MA; southwest side = WNEB-1230 Worcester, MA.
http://chowdanet.com/markc/WEB2005A/dx_wesx-wneb-1230.mp3
1490 kHz: northeast side = WCCM Haverhill-Lawrence, MA; southwest side = WMRC-1490 Milford, MA.
http://chowdanet.com/markc/WEB2005A/dx_wmrc-wccm-1490.mp3
1380 kHz: northeast side = WMYF Portsmouth, NH; southwest side = WNRI-1380 Woonsocket, RI.
http://chowdanet.com/markc/WEB2005A/dx_wnri-wmyf-1380.mp3
You pretty much get the indicated station in the clear with no evidence of the co-channel being picked up at the opposite end of the same antenna.
I would suppose you could do this with a DKAZ (having RF transformer or FLG100LN amp at both sides of antenna, two feedlines to shack) with even more dramatic results on more channels.
I expect to be putting up a Bowtie antenna, a double-loop similar in pick-up to DKAZ, within the next month. Maybe I can post a Perseus file from that or stereo audios similar to the above.
Other thing I could do is to flip mid-capture between a terminated loop facing east to one at a right angle, facing south, when there's enough Latin American activity to make it interesting.
Mark Connelly, WA1ION
South Yarmouth, MA
-----Original Message-----
From: Bill Whitacre bw@xxxxxxx [CapeDX] <CapeDX@xxxxxxxxxxxxxxx>
To: Mailing list for the International Radio Club of America <irca@xxxxxxxxxxxxxxxx>; am <am@xxxxxxxxxxx>; lbi-dx <lbi-dx@xxxxxxxxxxxxxxx>; coastalroundtable <coastalroundtable@xxxxxxxxxxxxxxx>; CapeDX <CapeDX@xxxxxxxxxxxxxxx>
Sent: Mon, Mar 7, 2016 9:29 am
Subject: [CapeDX] Switch from unterminated to terminated DKAZ caught on wav file!
Itâs 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. Itâs 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 â the âswitchâ from unterminated to terminated occurs at clock reading 1500:55 UTC. Short reason why is that I âfake outâ the clock on the CPU to start Mestor TOH recordings at :58 instead of the default :59.
The antenna is a 160â DKAZ âaimedâ at about 290 deg. with #20 wire terminated with a Vactrol set to about 900 Ohms but variable with a pot in the âshackâ [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 thatâs flat in the back..
With the antenna âpointingâ 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 âhealthyâ 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.
â
Hereâs a few ânot to missâ 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 "Vancouverâs traffic station!"
Did I mention the DKAZ is wide-band? I use the 160â version to get better low-band performance, shorter overall lengths work pretty well too though with some reduction in low-band performance.
To illustrate â
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
â
If youâre 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
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Posted by: Bill Whitacre <bw@xxxxxxx>
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