High vhf mods

[tvtn]

I have a question about modifications to HD7000R antenna. I would like to peak-cut the vhf elements (7 thru 13) for this and other winegard antennas like the HD 7010 and HD7015, all of which I still stock. Using a formula I found on the internet , CH 13 (shortest driven element) should be 13"- 5/32" and 16"- 5/16" CH 7 (longest driven element).This as compaired to a post I read on this forum for a simular request on this same antenna only regarding CH 9,11,and 13 which said 15" ( long element) and 9.5" for the shortest driven element.
I service two market areas: the Torrance or South Bay areas SW of LA,( ch 7,9,11,13) and the inland San Diego county area (ch 8 and 10). Having installed rooftop antennas since 1962, dealing with ATSC has changed a lot of my installion and set up of antennas and amplifers.
Thank you
Tom

[winegard]

Good morning tvtn,

Winegard can not say how these lengths would work. The antenna would have to be tuned and matched on an antenna range to verify results. If you wish to cut your elements and try it, this is your option.

[tvtn]

Thanks for looking at my post. Since the tech department made the reply that I mentioned in my first post (HD70000 high channel mods) is there a formula that I could use to get in the ball park? The person in your tech dept. stated in no uncertain terms that for the posters hi vhf channels ( ch 9-11-13 ) here are the lengths from the center of the driven element joints. I realize that if I experiment and cut up an antenna and it doesn't work its my bad not yours! Thanks in advance for any info you can share.
Tom

[winegard]

Good morning tvtn -

My suggestion would be to email one of our off-air antenna experts directly for more information on this subject. You can reach Hans Rabong at hrabo@winegard.com which will be your best bet.

[TomV]

What would be the advantage of peak-cutting your Winegard antennas?

[tvtn]

Tom,
The reason I am interested in modifying these antennas. (1) too much time on our hands in semi retirement. (2) An inventory of ch 2-69 antennas.(3) To reduce wind drag,bulk, (attics) and the shorter elements are less likely to be broken because of birds. (4) The smaller antennas don't have a lot of elements to cover the old or the new channel spectrum ( no need for elements long enough to cover ch 2-6).
Tom

[TomV]

OK, so you are hoping to get more gain at the Hi-VHF channels by using some of the now unused Lo-VHF elements cut to the Hi-VHF range?

[tvtn]

Tom
I have only done one experiment using HD7000s, one with cut driven elements and one uncut. At my shop in NE
San Diego I checked signal signals on digital ch 8 and 10 and found a small improvement with the cut antenna using a digital meter I purchased from Perfect 10. In addition to the reasons I stated in previous posts I believe on smaller antennas ( which spread the spectrum 2-69 or 7-51 across fewer driven elements) that cutting those VHFelements 2-13 to peak at ch 7-13 instead will produce more from the otherwise unused long driven elements. So far I have not done any thing to the UHF section. On my installs in the LA area typical distance is 40 mi. give or take a few, with everything from one mountain. In the area I live in San Diego north county, signals come different directions, so I am forced to use separate Vhf and Uhf mixed or preamped as the exact signal exposure dictates. I am no expert but I am having fun trying to find info on antenna theory and modification.
Tom