A couple of things --
If you are using 75-ohm hardline, you may want to use it only for the run
to the base of the tower. If you trim the hardline so that it is an
electrical multiple of a half wave at the lowest frequency you plan to use,
it will repeat whatever the input impedance is at the output end, meaning
that you can run 75-ohm to the stackmatch and 50-ohm from the stackmatch to
the antennas - I did this for a half-dozen years.
As for the Stackmatch, it is a nice piece of gear - but in my case, with
stacked tribanders, I have not found any occasion where the top antenna
alone is better than the stack. On the other hand, the lower antenna
alone, with its somewhat higher takeoff angle, is better on my path to
Europe during the waning hours of a band opening.
73, Pete N4ZR
At 03:16 PM 3/26/2009, Dave Johnson wrote:
>You said "stack match". If you are talking about the Array Solutions Stack
>Match, you may want to check with Jay about using 75 ohm feed line. His
>system uses equal length of 50 ohm feed line from the relay box on the tower
>to each antenna. How sweet it is to be able to use the high antenna alone,
>the low antenna alone or both antennas together.
>
>Dave - K4SSU
>
>
>----- Original Message -----
>From: <Cqtestk4xs@aol.com>
>To: <TOWERTALK@contesting.com>
>Sent: Thursday, March 26, 2009 2:03 PM
>Subject: Re: [TowerTalk] Stacking Antennas
>
>
> > In a message dated 3/26/2009 5:39:51 PM Greenwich Standard Time,
> > nq4u@mtars.org writes:
> >
> > Plans are to add a stack match.
> >
> > Both antennas will be fed with 75 ohm hardline cut to proper length. Wire
> > antennas will also be located on this tower.
> >
> > Will there be some pattern distortion due to different antenna spec's?
> >
> > What are some problems that others have had in stacking two different
> > antennas such as these?
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> >
> >
> >
> > Anecdotal here:
> >
> >>From what I've heard stacking dissimilar Yagis has been met with mixed
> > success. I'm not sure of the reasons. Boom length and phasing problems
> > come to
> > mind.
> >
> > I've been stacking IDENTICAL antennas since the 80's and have always been
> > successful.
> >
> > Bill KH7XS/K4XS
> > **************Great Deals on Dell 15" Laptops - Starting at $479
> >
> (http://pr.atwola.com/promoclk/100126575x1219799606x1201361003/aol?redir=http:%2F%2Fad.doub
> > leclick.net%2Fclk%3B213153745%3B34689725%3Bo)
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
>_______________________________________________
>
>
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|