[TowerTalk] Was April Fools, now radiating dummy loads

Roger L. Elowitz K2JAS@worldnet.att.net
Thu, 07 Aug 1997 23:16:57 -0400


Hi  Mark,

Your post was a beautiful response to my serious query. Thanks a
million.  Lot's of guys out there have learned something as a result of
your input as well as that of several others who took the time to
comment.  We're all obliged to you.

73,

Roger, K2JAS
==================================================
At 11:57 PM 8/7/97 +0000, you wrote:
>Roger asks:
>
>> But WAIT!  Didn't some company recently come out with a
>dipole center
>> connector that contained a large fifty ohm load resistor
>across the
>> coax terminals and the entire thing was sealed from
>prying eyes.  The
>> claim was that you could use this antenna on ALL BANDS
>with ANY LENGTH
>> OF WIRES and it would load beautifully!  I believe the
>claim was
>> accurate. I also believe the military bought loads of
>them.  I only
>> wish I were kidding on this one.
>> 
>> Please,  someone out there.... tell me it wasn't so or
>please confirm
>> what I'm saying is TRUE!
>> 
>
>I think it's been a number of years, but I believe that
>statement is true.  I would think some government employee
>or military technician would attempt to evaluate a sample
>unit, but in this case, I'm not sure.  However, dummy loads
>do radiate!  Put your Cantenna on top of your 100 foot
>tower, and attach a coax tee.  Plug in a dipole resonant at
>some frequency in the lower third of your coverage range. 
>The efficiency is going to be pretty poor, but what the
>heck, you are saving 3 db of loss in not using a tuner in
>trade for about 3 to 20 db less radiated signal across the
>coverage range.  No problem, just run 150000 watts output
>and the far end won't tell the difference!  Probably
>quieter on receive, too <grin>.
>
>Reminds me of long ago days at W8UM when we worked a fellow
>in one of the dorms about 2 miles line of sight when tuning
>the 32S3 into a dummy load.  I think he gave us an S8 or
>so.  Asked him to stand by while we tried a new antenna. 
>Flipped on the 30L1 and switched to the 40m yagi which was
>pointed in the appropriate direction.  "Hows the signal
>now?".. hehehe
>
>Seriously, there have been what I would call reasonable
>attempts to make relatively efficient broadband shortened
>transmitting antennas using resitive loading.  The T2FD
>comes to mind as one that has seen more than a little use
>over the years.  I believe the B&W folks are still
>manufacturing a dipole and unipole (grounded end) version
>of the T2FD.  And then there is my first novice antenna, a
>Hy-Gain base loaded 18V with a three foot ground rod, no
>radials, mounted a foot from a chain link fence.  With the
>losses taken into account, that antenna qualifies as a (not
>quite) radiating dummy load.  After two weeks of after
>school CQ'ing, I finally worked a fellow in the next suburb
>(15 miles or so) who gave me a 569C report for my first
>QSO.  I was quickly instructed as to the advantages of the
>simple inverted V, it's been a blast ever since!
> 
>Then there is the terminated V and rhombic class of
>antennas, where you are more or less diverting power that
>would radiate to the "rear" of the antenna into the
>terminations, thereby gaining a unidirectional antenna. 
>Ya, not exactly technically correct, but it settled well
>when I gave a two session introductory antenna forum at a
>new novice class back in Chicagoland.  
>
>
>
>----------------------------------------
>Mark Shaum  K9TR
>mashaum@fcg.net
>Central Illinois Grid EN50
>---------------------------------------
>
>
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