[TowerTalk] combining TV antennas

[Roger (K8RI) on TT]

On 8/19/2014 8:21 PM, Dick NY1E wrote:

It works fine, splitter or combiner.  Many say they work for both.  I 
had a pair of the longest UHF Yagis with corner reflectors.  However, 
you will not get the gain you do with a single antenna.  An antenna gets 
gain by increasing it in the desired direction and Reducing it in 
unwanted directions.  It's not just the combiner mismatch.  The signals 
add vectorially or algebraically  so it's rare for the signals of both 
to add. It's highly unlikely you will ever get a signal to cancel 
because of the differences in gain UNLESS the two antennas are within 
30-60 degrees of each other, the signal falls on a minor lobe of both 
antennas and the phase difference is 180 degrees. OTOH However, unless 
you are working stations right at the threshold, they will be fine.

With one at 90 feet and  160 degrees and one at 95 feet at roughly 
300-310  From Midland I could receive most of the Detroit, 
Lansing/Jackson as well as Cadillac and Traverse City areas with solid 
signals, analog or digital. Roughly 20 stations.  I used a combiner into 
a preamp where the coax reached the tower from the antennas.  The TV 
antennas were about 20-25 feet below the 7L C3i 6-meter Yagi and about 
30-35 feet below the 144/440 array with no problems either way. EXCEPT 
if the 2-meter and 144 antennas ere pointed in roughly the same 
direction, 160W on 2 would bother Ch 12 analog.  No problems on digital.

Replacing the preamp was a once-a-year ritual, but back then the tower 
was taking an average of 3 visually verified direct lightening strikes 
per Summer. No verified strikes in the last 5 years.  "I think" a near 
strike a couple of weeks back took out my router and switch plus the NIC 
on my wife's computer.  I "assume" it was a near strike as there were no 
other problems. Of course the tower took 17 verified hits with no 
damage.  Before the ground system was finished, I did lose a new 
computer and the front end on a 2-meter rig.

73 and good luck,

Roger (K8RI)

> Can I use a splitter to combine 2 TV yagis pointed in different directions? Does making the feedlines from the spilitter the same length matter in this case?
> Dick NY1E
> _______________________________________________
>
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