[50mhz] Stack spacing question

[Mark Drieci]

Danny, I believe your  statement is  correct.  Too many times in my career
as an engineer I have ignored the maxim of expedience, that is, "A
difference that makes no difference is no difference."  In this case, doing
it by the textbook isn't really going to make a noticeable difference.

I've decided to go with a 9 foot spacing with the two meter yagi on the top,
and the six meter yagi below.  Roger, K4RW runs a similar configuration and
is very happy with it.

With 10 days left of the 30 day concrete curing period, I'm ready to proceed
with the erection of the tower!

Thanks to everyone who took time out of their Saturday to contribute their
opinions.  It is appreciated.

73,
Mark - KA4MAY
EM78, Lawrenceburg, Kentucky

-----Original Message-----
From: Danny Pease [mailto:dpease at adams.net] 
Sent: Saturday, August 20, 2011 10:02 AM
To: 'Carl'; 'Mark Drieci'; 50mhz at mailman.qth.net
Subject: RE: [50mhz] Stack spacing question

Theory and conventional wisdom are not always obtainable.

I have seen installations of 6 and 2 meter beams with as little as 2 foot
separation and performance was as good as a single antenna on a tower by
itself. WD5AGO did some testing on VHF and UHF antennas and his results
showed very little change in performance up to the point the SWR was
affected by the close spacing. Many rovers have antennas within inches of
each other and get very good performance.

My personal thinking is use all the spacing you can provide and don't get
bent out of shape if it isn't as much as "conventional wisdom" says you
need.

Danny NG9R


-----Original Message-----
From: 50mhz-bounces at mailman.qth.net [mailto:50mhz-bounces at mailman.qth.net]
On Behalf Of Carl
Sent: Saturday, August 20, 2011 8:32 AM
To: Mark Drieci; 50mhz at mailman.qth.net
Subject: Re: [50mhz] Stack spacing question

What sort of conventional wisdom? Electrical or mechanical?

I currently have a 3 el 20M on a 21' boom, next up is a 28' boom on 432 and
and at the top is 35' of 8el for 6M.
Spacing bottom up is 4' and 5' and the 432/50MHz appear to work exactly as
when tested alone. Another 432 will be added  soon.

Carl
KM1H



----- Original Message -----
From: "Mark Drieci" <guitar0145 at gmail.com>
To: <50mhz at mailman.qth.net>
Sent: Saturday, August 20, 2011 4:43 AM
Subject: [50mhz] Stack spacing question


>I am erecting a new VHF tower with a modified Cushcraft A505 (18 foot boom)
> and a Cushcraft 17B2 (31 foot boom) in a vertical stack.
>
> Conventional wisdom suggests that the 6M antenna be placed atop the 2M
> antenna as it has the shorter boom.
>
>
>
> I have read the section of the ARRL Antenna book where it describes 
> stacking
> scenarios of the 2M over 6M beams, but there are none described that are
> similar to my own.
>
> I am seeking input from the list members on the optimal stacking distance
> between the two yagis to minimize interaction
>
>
>
> Any comments on this subject are greatly appreciated.
>
>
>
> Thank you in advance.
>
>
>
> Mark - KA4MAY
>
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