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Re: [IRCA] [NRC-AM] DKAZ Antenna

Nick:  See CAPS below

Mark Durenberger
-----Original Message----- From: Nick Hall-Patch
I haven't had experience with two D-Kaz Mark, but do I gather then that you haven't seen evidence of null steering with the DKaz alone? I HAVEN'T SEEN EVIDENCE OF STEERING, JUST DEPTH ADJUSTMENT (PRESUMABLY INCLUDING RE-SHAPING OF SIDE-LOBES).
FROM WHAT I'M LEARNING ABOUT THIS ANTENNA, SOME FORM OF DIFFERENTIAL DELAY IS NEEDED BETWEEN MULTIPLE ELEMENTS TO ACTUALLY STEER THE NULL. KAZ HAS STAGGERED THEM PHYSICALLY, BUT ONE ASSUMES YOU MIGHT ALSO BE ABLE TO DO THIS BY PHASING TWO ANTENNAS. YES MORE VACATION TIME IS NEEDED!
I will need to look at the readings I recorded with a fresh eye. There isn't much right off the back of an east- west DKaz at Grayland for comparison, so it may be truer to say that nulls can be improved as Chuck pointed out. But, it doesn't seem to be fine tuning about a fixed value of 900 ohms....perhaps more frequency dependent, or ? I'M OF COURSE CURIOUS ABOUT WHAT CHUCK HAS BEEN FINDING FOR NULL-IMPROVEMENT.
I had observed similar (and <900 ohms) termination values for Portland on 1190 and Seattle on 1000, one 50 degrees off the back of the antenna, one 30 degrees, but realize that although Portland on 620 and and Seattle on 710 also had similar values of termination, that value was higher. And to throw it all out, Portland area on
1640 and Seattle on 1680 had different values of termination altogether. THIS THOUGHT REMINDS ME THAT THERE'S NO SUBSTITUTE FOR ACTUAL NULL-ADJUSTMENT. THE CURRENT CONVENTION SEEMS TO BE TO DERIVE F/B RATIOS BY SWITCHING THE NULL-RESISTANCE IN AND OUT; I.E. MEASURING THE ANTENNA PERFORMANCE WITH NO NULLING ("BI-DIRECTIONAL?) VS. THE PERFORMANCE WITH THE NULL RESISTANCE IN AND ADJUSTED.
AND THIS IS A "YMMV" COMMENT. WHEN I USE A FIXED RESISTANCE FOR SDR RECORDING ACROSS THE BAND, I DO A SIMPLE ARITHMETIC CALCULATION, AVERAGING THE NULL VALUES FROM 15 TO 20 "BEST F/B" NULL-RESISTANCE MEASUREMENTS. IF ONE WAS INTERESTED IN JUST A SEGMENT OF THE MW BAND, ONE COULD AVERAGE THE NULL RESISTANCES ACROSS JUST THAT SPECTRUM...?
I'VE ALSO WONDERED WHY WE'RE NOT PAYING ATTENTION TO OTHER FACTORS WHEN AUTOMATICALLY SPECIFYING "900 OHMS" (A SO-CALLED FLAG 'STANDARD.' ) WHEN I SET MY D-KAZ TO WORK EARLY THIS SUMMER WITH #18 WIRE, I WAS FINDING NULLS AT "SOMEWHERE ABOVE 800 OHMS" BUT RARELY NEAR 900 OR ABOVE.
WHEN I REBUILT THE ARRAY USING #16 WIRE, THE NULLS WERE FOUND BELOW 800 OHMS. I QUERIED KAZ, WHO SUGGESTED THE LOWER WIRE RESISTANCE COULD BE THE REASON FOR THE CHANGE.
WHEN I RECENTLY MOVED THE ANTENNA TO A NEW ORIENTATION (MOVING FROM A CLEARED SPACE TO A SPACE WITHIN A LOT OF TREES) I FOUND YET ANOTHER SET OF NULL RESISTANCES. 

SO I AGREE WITH YOU---A LOT MORE OPEN-MINDED OBSERVATION WILL BE OF BENEFIT.
THE TRUE HIGHLIGHT OF THIS EXCELLENT ANTENNA IS THAT KAZ IS UTTERLY SUPPORTIVE OF OUR EFFORTS TO LEARN MORE! 

CHEERS!

MD

best wishes,

Nick


At 11:30 20-08-15, you wrote:
You CAN steer the D-Kaz by introducing a mechanical offset but you need two antennas; one in front of the other. I think you're right about what Nick meant.
BTW: We're now playing with phasing, by adding a vertical at the "null" end of a single D-Kaz. Single frequencies can be knocked out of the ballpark (great Pest control) and adjacent channels do benefit from that additional nulling. 


Cheers!

Mark Durenberger

-----Original Message----- From: Chuck Hutton
Sent: Wednesday, August 19, 2015 11:47 PM
To: irca@xxxxxxxxxxxxxxxx
Subject: Re: [IRCA] [NRC-AM] DKAZ Antenna

Nick -
Are you saying the DKAZ null can actually be steered? If so, how much?Or are you saying that deepening the null at 180 degrees means that the null at other angles near 180 benefit from the deeper 180 null? (Assumedly the latter. I've not been able to steer a DKAZ null, only improve it a bit.) 
Chuck


Date: Thu, 20 Aug 2015 04:37:15 +0000
To: irca@xxxxxxxxxxxxxxxx
From: nhp@xxxxxxxx
Subject: Re: [IRCA] [NRC-AM]  DKAZ Antenna

If you get ambitious Jim, try a Vactrol termination, like Mark C.
used in  his Flag antenna.   It's amazing how stations fairly far off
the exact back end of the antenna get better nulls with a remotely
variable termination.  At Grayland, it even helped kill the local noise..

best wishes,

Nick


At 15:29 19-08-15, you wrote:
>Hi Neil,
>
>Thanks from a happy DKAZ user. The antenna took 3 weekends to build,
>due to the Texas heat, clearing a path through the trees and
>gathering all the supplies. I decided to make this a permanent
>installation, using 4"x4" timber posts for the main supports and 2"
>electrical PVC pipe for the 22' supports, all seemed to work just fine..
>As for the termination, I will try a 5k pot and see if I can get a
>better null to the north. The Dallas station come in pretty good
>here, 570 KLIF, 820 WBAP, these would be the stations I would like
>to null. Also, at present I am using coax direct onto the feed end
>of the antenna, so I have not added the matching transformer as
yet, next >step.
>
>As for San Angelo stations, I have only logged KGKL 960 but nothing
>else at present.
>I really don't have enough width on my land for a side by side DKAZ,
>sounds like a great idea though.
>I am presently working on my Spanish, I know some which helps with
>station identifications, but more is helpful.
>
>Thanks
>James
>
>
>
>---- neilkaz <neilkaz@xxxxxxxxxxxxx> wrote:
> > This is good to hear about another happy DKAZ user. You may find
> that you are an even more happy DKAZ user if you spend the effort
> to manually fine tune Rt to see if you can get even better back
> nulls. This is best done in the daytime. I'd guess you might
> improve back nulls by a few dB unless 900 ohms is perfect. I do
> realize that you probably don't have much daytime stuff from 300
> deg into Austin. Does San Angelo come in?
> >
> > Do you have land to array two of these side by side for a more
> narrow beamwidth?
> >
> > If not fluent in Spanish aimed at 120 from Austin, I expect
> you'll want to improve your command of that language.  73 KAZ
> >
> > -----Original Message-----
> > >From: James Niven <jniven@xxxxxxxxxxxxx>
> > >Sent: Aug 18, 2015 8:11 PM
> > >To: 'NRC' <am@xxxxxxxxxxx>
> > >Cc: 'Mailing list for the International Radio Club of America'
> <irca@xxxxxxxxxxxxxxxx>
> > >Subject: [IRCA] DKAZ Antenna
> > >
> > >Hi All,
> > >
> > >
> > >
> > >Just wanted to report I have completed my DKAZ antenna over the
> past weekend
> > >and I have had a chance to test it out the past few nights.
> > >
> > >I followed the design as Mark Durenberger's article
> > >http://www.durenberger.com/documents/DKAZREPORT051214.pdf I
built the > > >140
> > >foot long with 22 feet high supports. I am at present using a
> 900 ohm fixed
> > >1 watt resistor and the direction is 120 degree.
> > >
> > >
> > >
> > >I have been comparing the DKAZ to my present 150 foot
longwire > > >running
> > >pretty much in the same direction, so far, the performance of
the > > >DKAZ has
> > >been very encouraging. Signals are appearing a lot stronger
and > > >earlier in
> > >the evening than the Longwire and I can tell signals from the
north > > >are
> > >reduced, while signals from the South are a lot stronger and louder.
> > >
> > >
> > >
> > >On a couple of frequencies I have checked, on the DKAZ there
is a > > >station
> > >with a decent signal while the Longwire has no station at all or
> a different
> > >station.
> > >
> > >I am still to hear a new station with this antenna but it
will > > >happen.
> > >
> > >
> > >
> > >Thanks for the fine article Mark and answering my questions.
> > >
> > >
> > >
> > >James Niven
> > >
> > >Austin, Texas
> > >
> > >
> > >
> > >
> > >
> > >---
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