[TowerTalk] Fwd: How to get another 10' in height? Add a

[Jim Thomson]

Date: Fri, 13 Jan 2012 16:10:39 +0100
From: "Peter Voelpel" <df3kv at t-online.de>
Subject: Re: [TowerTalk] Fwd: How to get another 10' in height? Add a
mast

I wonder about the interaction.
I don?t think a VHF contester would install his antennas for 6m,2m and 70cm
with only 2" separation

73
Peter, DJ7WW

## You may well be correct, but... optibeam + F-12 manage to put several bands on the
same boom.   It's the best compromise we could cook up. I made one error though. There
are two 15m yagis on that tower, not one.   So  3 x 20m yagi's,  2 x 40m yagi's, 2 x 15m yagi's
1 x 17m yagi, 1 x 12m yagi and one 10m yagi..+ 1 x 80m yagi.  Only one 6m yagi.  It was going to be 2 x 6m yagi's,
but that was stretching things a bit much. Originally, it was to include a 3 x el 30M yagi.  The 30M
yagi got dumped, and replaced with a 2nd 15M yagi.   Everything is pointed in the same direction
of course. On the old tower, it was 4 x tic rings.   On the old tower set up, the various yagi's in the
stack could be switched in any config you wanted, with the wx0b switch box.  In the new config, the
yagi's are all driven in phase, all the time. I designed the L networks for 40/20/15m . Just one tubing coil
+ a mess of paralleled 5 kv NPO surplus doorknobs. 

##  the only thing that does not work at all very good was the BIP /BOP  function on the 40m stack.  
A vac relay switch's  in an electrical 1/2 wave of coax into one leg of the upper yagi.   The BOP
function is miserable at best.  Only once did the signals on 40m get stronger in the BOP mode on 40m.
That was while listening to a 40m daytine roundtable net.  And only 1 station of the 12 on freq was a bit louder
in the BOP mode.   After hundreds of tests, day and night, the consensus is the BOP mode is a dud.  Too bad,
we were expecting  much more from it too.   Bottom 40m yagi is at 89'....and top one is at 180'. 

## what ever interaction you think exists with having  the 80/40/20m yagi's  equally spaced on that 25'  
unsupported 55-G above the top ring does not show up during actual usage.  The thing is a literal 
flame thrower on 80/40/20/15m.  It also smokes on 17/12/10/6m.  It appears that 12.5'  spacing between
the 80/40/20m works pretty good.  At best, decisions had to be made, and we didn't want to compromise the
mechanical intergrity.  The best compromise I could think of was using the 3 x heavy duty 55-G section's
at the very top, with 25' of it  above the top ring.  3 x guy anchors used..and all guy lines are made of 3/8"
fiberglass  rod material.      

##  BTW, F-12 claims you can install their 340N yagi  within 3' of a F-12 20m yagi, or F-12 multibander yagi..and
no interaction. The 340N  will resonate just below 12m band..and mess up 12 only.    I will  find out if their claims
are correct this spring, when my 340N get's installed...just below the F-12  5-el, 20m yagi. 

later... Jim   VE7RF


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Jim Thomson

So he has 25`feet of unsupported tower above the top ring.  A 2-el 80m yagi
is at the very top of the tower.  4-el 40m yagi
below that..and a 5-el 20m yagi below that..all  in that  25 foot
unsupported section