Re: [IRCA] New Flag Antenna results

[neilkaz <neilkaz@xxxxxxxxxxxxx>]

Good news here, Jim, and happy to have helped. I few comments if I may. Jim has built a simple basic verson of a bottom corner fed flag antenna. The transformer used is a standard 18:1 (900/50 ohm) from K0FF (Clark Electronics, Belfast ME) The resistors I gave Jim are Radio Shack cheap 1000 ohms and as we see Jim's basic Flag works well terminated with 1000 ohms. The wire is normal 14 gauge stranded wire sold at Home Depot and similar and is rather hard to break.

I had some concerns that common-mode snake currents might be a factor messing up nulls and that much coax, but apparently not. At some point, Jim, you may want to switch to the current state of the art using 9:1 transformers at each end of the Flag, into speaker wire or zip cord (about 110 ohms) both fed back to the shack to 2:1 transformer on one end and a pot on the other to remotely vary termination resistance for better nulls. A switched arrangement is also possible to reverse the direction of null. Others can give you more info here. The benefit of speaker wire for long runs rather than cable is that it is balanced and less susceptable to common mode pick up.

When I get a chance (am very busy now) I will model your exact dimension in EZNEC just to make sure that a different fixed resistance isn't clearly better for nulls.

Re: your DX... You guys east of me do a better job of getting Egypt thru Spain on 774 that I do from WI (channel is clobber in IL) where it is 99%+ to have Spain way atop. 549 Algeria upgraded their facilities recently. If you sit on 693 Spain can fade up // RNE as can Azores // RDP. 1060 CKMX seems to be running Day pattern at night this season. There is no change in level at their sunset switch time. Keep trying for 783 Mauritania // 4845 and you'll get them. This can come in slightly presunset when, for you, WBBM shouldn't matter. 1134 Spain is possible. A month ago from WI there was weak SS // COPE overnight stuff.

Jim from looking at Google Earth, I think your NE longwire is much more North than NE and likely aimed a bit too far northerly for most TA's. Note also that elevated mini-Bevs like that several hundred feet long, have great back end pick up, likely giving you lots of domestic QRM. So it is no surprise that the flag is more useful for TA's in general.

Perhaps you have WLW knocked down enough to DX 702 for TA's although there's nothing strong there. You should be able to DX 837 with ease with WHAS nulled. I suspect KDKA is nicely nulled on the flag, perhaps so buried in WBZ IBOC that you can't tell.

73 KAZ


-----Original Message-----
>From: Jim Renfrew <jrenfrew@xxxxxxxxxxxxxxxx>
>Sent: Sep 20, 2010 10:32 PM
>To: am@xxxxxxxxxxx, amdx@xxxxxxxxxx, Mailing list for the International Radio Club of America <irca@xxxxxxxxxxxxxxxx>
>Cc: contiba@xxxxxxxxx
>Subject: [IRCA] New Flag Antenna results
>
>Jim Renfrew, Holley NY
>
>Some of you who attended the NRC convention heard Neil Kazaross' workshop on 
>flag antennas.  With his guidance I've built one.  Using three trees in a 
>line, aimed NE/SW I put up the Flag in the front yard, with the lower wire 8 
>feet off the ground, and the upper wire 25 feet.  I couldn't get any higher 
>with the 40 foot ladder, two trees were too narrow to support the ladder at 
>that height, and the third tree was a mess of branches.  If necessary I can 
>drop the lower wire to ground level after the lawn-mowing seaason, or even 
>put it under ground with a conduit.  The length of the antenna is about 85 
>feet.  Neil provided a 9:1 transformer.  There is a 475 ohm resister at the 
>far bottom corner.  There is a 125 foot coax into the house, but there 
>doesn't seem to be appreciable signal loss.   I use a Drake R8B.  Other 
>wires are a south wire (200 feet), an east/west wire (700 feet), and a 
>northeast wire (about 600-700 feet).  Flag results are very positive.  Most 
>of these receptions are not found with the northeast longwire (or 
>substantially weaker), but present with the Flag.  Stations to the 
>southwest, like WLW, WSB, WHAS, or WTAM, are depressed about 15-30 dB using 
>the Flag.
>
>Here's what I've noted tonight, times EDT:
>
>2229    774    Koranic reading, faded before I could get a Global Tuners 
>receiver to try to match it.  Egypt likely.
>2243    1089    UK excellent
>2244    1341    Weak audio, North Ireland likely
>2250    1377    France, very good
>2251    1521    Audio in heavy WWKB slop, Saudi I suppose
>2252    549    Arabic, something here but language may be wishful thinking. 
>Algeria and Germany have been heard here.
>2253    693    BBC very good
>2254    738    Spain, fair, enough to ID language
>2255    747    Netherlands    "I Can hear Music", appropriately
>2256    855    Spain // 738
>2246    1053    UK I guess, but too weak to ID or to compare with 1089.
>2308    1060    CKMX Calgary - matches web audio and song list.  Blasting 
>KYW on all antennas.  Fades in and out.
>2316    1134    Croatia now off at this late hour, but a het is noted.
>2318    1215    Absolute Radio
>
>Yesterday at 1915 I had an interesting signal on 783 kHz, might have been 
>Mauritania or Syria.  I couldn't make it match the Mauritania shortwave 
>station, and I couldn't find a web audio for Syria that worked.  It was not 
>Barcelona, Portrugal or Germany.  I think this was Syria, heard last year in 
>December.
>
>I'm disappointed to note that more than a few Global Tuners receivers are no 
>longer listed.
>
>Thanks to Neil and Chris Black for the guidance on putting this together.
>
>Bruce, I'm sorry that this isn't in the form needed for IDXD, but perhaps 
>you can make this into a feature after the regular reports.  People who 
>attended the convention will be interested in this.  More than a few people 
>have expressed an interest or intion to build one fo these. 
>
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