[TowerTalk] Re: [antennaware] 18HT (Hytower) mod help

[K7GCO@aol.com]

Tim: Since I wrote the article 30 years ago perhaps I can help (I thought you 
would never ask).  You have not made clear what you are trying to do.  You 
mention 75&40 and it's already resonant there without using L networks.  
Dropping a wire down for 25' 3" from the top will not make it 25' longer, 
maybe only 10' as it's too close and is a way to lower it to CW with top 
loading.  Base loading will do the same and it's easier to change. You might 
check where it's resonant at now.  With the extra length you will need only a 
BC variable 3 gang Xc to resonant it on 75M and it will have a slightly 
higher Rr which is an advantage.  This is a little used technique that is 
very effective in particular for raising the Rr which I also use in mobile.  
This enhancement that is worth while.

Now if you would run that 25' wire out like a guy wire at 45 degrees it will 
give you a lower resonant frequency out of the band.  In the band the Rr 
should be a little higher and use the series Xc for low SWR.  If it's too far 
above 50 ohms, use an L network.  If you run it from the top at right angles 
for say 65' you will have a bent 1/4 wave L and direct feed for l60M and need 
160M radials.  The Z will be less than 50 so there is a Xc value (use fixed 
and a variable) when paralleled across the feedpoint and a certain longer 
length of wire added on the end (or in series at the base) that will give 50 
ohms.  It's a form of an L network with one component added at the feedpoint. 
 Now you have on 75M the equivalent of the top loading I had, a bent 1/2 wave 
(or make it a T with equal lengths on both side) on 80/75 and Hi-Z feed using 
an L network.  Use the inductor to ground and a variable Xc from the center 
of the coax on 80/75&40 to the top of the coil.  L networks are easy to 
adjust.  Have an inductor you can tap and a BC Variable Xc.  Using the MFJ 
analyzer set at the desired frequency and using different taps, vary the Xc.  
All of a sudden--1:1 SWR with great bandwidth with minimum radials.  Use a 
ground rod as minimum ground for shield connection.  

This is also a 1 WL L on 40, Hi-Z feed again with the L network.  You can't 
do better than this for simplicity and performance.  This concept is 
applicable to any 1/4 wave on 75.  You will have to short out the 40M 1/4 
wave Hy-Tower "sleeve" at the top to the center wire and pipe when used on 
40M or you will get Lo-Z feed again.   

There is another trick of adding an 80M 1/4 wave open wire line at the top as 
a 80/75M trap and use it a lose guy wire.  This give 3 band direct feed.  
Connect to the tip of the antenna near the open end of the one of the 1/4 
wave open wire lines (use the light 450 ohm stuff).  Assume a connection on 
the 80/75M stub is 5' from the open end, pull this stub away from the 
aluminum tubing like another guy.  The actual connection point is determined 
by the angle of the wire to the aluminum tubing and the area of the 160M you 
operate.  I had a lot of this in a Radio Sporting Mag about 15 years ago but 
its all packed or I could send you a copy.  It was a big article on improving 
trap verticals and the Hy Tower.  K7GCO

PS: Does anyone know anything about the International Inc Model 400 Single 
Channel Mic Processor?  I'm into heavy audio and I have a chance to buy one.  
One problem is that is has balanced input and output.  Who are the BC audio 
SSB guys on 20M that would know this and how effective it is?      

In a message dated 12.03.00 17:41:28 Pacific Standard Time, tkass@netzero.net 
writes:
<< 
 Hello antenna gurus....need some advice...have one of the old Hygain
 hytowers..great antenna but trying to make it better..since I operate
 mainly on 75 and 40 SSB..wanted to enhance the antenna....working from a
 modified article from on old CQ magazine (K7GCO)...instead of sticking a
 loading coil at the top of the vertical, necessitating guy wires (aarrr) ,
 instead I used some linear loading techniques...took a wire from the top
 of the vertical and ran it along the side of the vertical to the tower
 section where it is connected to a insulator..the wire stands off about
 3 inches from the vertical "whip" all the way down to the top of the
 tower section...also have been using elevated radials, several for 40
 and 2 for 75 presently....presently, the tower is fed using an L network
 to match it for 75 mtr...future plan is to use some type of remote
 switching with permanent L networks for 40 and 75  mtr....the Question I
 have. .the physical element length is 78 feet..53 feet to the top and
 the addition of 25 feet of wire added..does this scheme seem appropriate
  to you guys..have been running this for about 1 week..with good results
 thus far...any comments would be greatly appreciated..  73   Tim +
 WB8OWX
 

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