That sort of "the next step is awfully expensive" applies to a whole lot of
things in life, though. Squeezing that next couple of dB gets more and more
expensive as you move up...
Dick, K6KR
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Drax
Felton
Sent: Thursday, August 01, 2013 10:57 AM
To: Steve Dyer
Cc: Jim Thomson; towertalk@contesting.com
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@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@telus.net>
> To: towertalk@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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