[TowerTalk] Optimium Tower Height

[Jim Thomson]

Subject: Optimium Tower Height


Date: Sat, 22 May 2010 05:48:41 -0400
From: Pete Smith <n4zr at contesting.com>
Subject: Re: [TowerTalk] Optimium Tower Height

This is also the advice I was given 15 years ago by a very well-known 
and technically accomplished local multi-multi owner - he said if you 
only plan one tower, make it 100 feet.  I altered my plans accordingly, 
and am very glad I did it.

73, Pete N4ZR

On 5/21/2010 7:35 PM, john at kk9a.com wrote:
> According to (sk)W2PV's Yagi Antenna Design book a good height is 1 1/2
> wavelengths high.

## 1.5 wave lengths is 100' on 20m... but is 3 wave lengths on 10 m! 
He doesn't mention a 40 m rotary dipole or 40m yagi in his proposal. 
Even if wire ants used on the low bands... they will work better up 
100'  vs 70'.    If he wants to shunt feed the tower on 160m.. again
a 100' tower will work better vs 70'.  Considering the 100' tower is
2 wave length's on 15M.. and 3 waves  on 10m.... he might want to
consider either a tic ring or side mount rotor... and a 2nd TH7 down
the road...at a lower height... say 50' [just above guys]. If that is the
case, you will want to consider the guying levels used... and whether
the 2nd TH-7  will rotate freely. 

## even a 40m rotary dipole is a good ant,..if up high enough. The F/S
alone will justify it.  A friend had 4 x tic rings on 160'  of 45-G.. + a 
protistel on top.  You can hang a lot of AL  off  rohn 45g. 

##  2 x TH-7's  @  say 55'  and 100'  would work very well...esp if they
can be pointed in diff directions.  Then toss in the  top,bottom, both in phase,
both out of phase combo's, then u have a killer combo.  You might even
want to make it higher..like 110-130'.... then you have room to hang all
sorts of stuff on it... including fixed yagi's.. or vhf/uhf ants. 

## if you have room for 100' to 130'... I'd suggest to go for it.  A 2nd
tri-bander, lower down will take care of the high angle stuff..if needed. 

Later........ Jim   VE7RF



>
>> I have started my Rohn 45 tower projhect. I am planning to put a Cushcraft
> A3WS and a TH7DX atop this tower. I was planning on erecting a 100 foot
> tower but a fellow ham suggested that that might be too high. What in the
> groups informed opinion would be an ideal height for these antennas?
>
>
> I appreciate your input
>
>
> 73 Mark N1UK
>
> _______________________________________________