[TowerTalk] How High is enough

[Gene Fuller]

All kinds of good possibilities with 70 feet. Great height for 10-20 m. 
Works for 80 m quarterwave slopers. Not bad for 160 meter inverted L. Good 
for a 40 m bent vertical dipole array or with a husky mast, 2 elements on 40 
at about 80 feet would play quite well.
Gene / W2LU

---- Original Message ----- 
From: "Drax Felton" <draxfelton at gmail.com>
To: "Steve Dyer" <w1srd at yahoo.com>
Cc: "Jim Thomson" <jim.thom at telus.net>; <towertalk at contesting.com>
Sent: Thursday, August 01, 2013 1:56 PM
Subject: Re: [TowerTalk] How High is enough


> When I looked into crank ups it doubled the price to go from 90 to 120 ft
>
> That last 30 feet is mightily expensive compared to the benefit.
>
> Sent from my iPhone
>
> On Aug 1, 2013, at 12:41 PM, Steve Dyer <w1srd at yahoo.com> wrote:
>
>> I suspect that's why ~70 feet is the sweet spot for crank-ups. Get's you 
>> a 1/2 wave on 40 and full wave on 20.
>>
>> The big question is always, what is the incremental gain for the $$ 
>> spent/extra effort over a baseline.
>>
>> 73,
>>
>> Steve
>>
>>
>>
>>
>>
>> ________________________________
>> From: Jim Thomson <jim.thom at telus.net>
>> To: towertalk at contesting.com
>> Sent: Thursday, August 1, 2013 8:36 AM
>> Subject: Re: [TowerTalk] How High is enough
>>
>>
>> It has been mentioned that if you could only put up 1 tower, that 100 
>> foot would be ideal.
>> Why not higher ?   I helped with the design of a 190 foot rotatable tower 
>> for a buddy
>> just south of me.  Yagis  for 80-6m..including 17+12m..but no 30m.  2 x 
>> Stacked yagis  on
>> 15m..and also 40m.     3 yagis used on 20m.   All ants  pointed in the 
>> same direction at all times.
>>
>> He is a dxer...not a contester.  I designed the LC  box  for  20m and 
>> also 40m.   All  3 x 20m
>> yagis  driven in phase at all times..and ditto with 40m.
>>
>> On 40m, I designed the BIP-BOP  mod, using vac relays built into the 40m 
>> LC box.   40m yagis
>> at 90 foot and also 180 feet.   The BIP-BOP for 40m was a huge 
>> disappointment. Only once on 40m,
>> during the day, was BOP louder...and that was while listening to a group 
>> in Ore, 280 miles south.
>> BIP reigns supreme the other 99.9999 %  of the time.   That’s  day or 
>> night, any direction, any time,
>> and day of the year,  short path, long path, local or dx..... for the 
>> last 3 years.
>>
>> I was expecting  a lot more from the 40m BIP-BOP box.  It was triple 
>> checked too.   An electrical half wave
>> was switched into the bottom yagi  for BOP mode.
>> The LC boxes are simple.   Just a shunt C..made from NPO caps on the 
>> input, with a series L  made from
>> copper tubing, then  either    2 or 3 paralleled output coax connectors. 
>> 50 ohms in and 25 ohms out..on 40m.
>> 50 ohms in and 16.66 ohms out on 20m.   Equal length  coax to each yagi .
>>
>> A lot of this  tower height argument will depend on available  real 
>> estate.  City lot or acreage.
>> In typ city suburbs, homes can be as  high as 30 feet.  Typ utility poles 
>> are as high as 40 feet, then the
>> steel  support above that, so perhaps 41.5 feet...then the 12.5 – 14.4 kv 
>> line  strung between poles at the
>> 41 foot level.
>>
>> Put the yagi up at 35-40 feet..and imo,  you are wasting your time.   You 
>> are not even clearing the power lines, trees,
>> homes on the high side of you etc.   Even at 50 feet, you are barely 
>> clearly  this stuff.   75 feet is a good compromise
>> between  50 and 100 feet.   When I increased height from 48 ft to  67 ft, 
>> the difference was apples and oranges.
>> On 20m, a yagi at 100 ft  has a huge null at 20 degs.  Same yagi at 50 ft 
>> has max gain at 20 degs.  Put the same yagi
>> at 75 ft...and max gain is at 15 deg..and no need for a high-low 
>> switching setup.   If 100 ft is too high on 20m,
>> sure come down a bit..but not down to 50 ft.   At least here in the 
>> pacific north west.
>>
>> Jim   VE7RF
>> _______________________________________________
>>
>>
>>
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