Converting UHF Yagi to a VHF Antenna - Canadian TV, Computing and Home Theatre Forums

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post #1 of 104 (permalink) Old 2019-06-18, 03:20 PM Thread Starter
 
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Location: Randolph NJ 30 miles west of ESB/1WTC
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Converting UHF Yagi to a VHF Antenna

I have a 5 foot long UHF Uda Yagi style antenna that I have no use for but could use another VHF antenna for a VHF channel broadcast in a different direction from the main VHF stations. I tried giving it away and there were no takers so I was wondering if I could possibly re-purpose it with the right modifications?

I haven't posted in awhile and have to now try to figure out how to post a picture of the antenna which I will figure out and post later.
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post #2 of 104 (permalink) Old 2019-06-18, 03:28 PM Thread Starter
 
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post #3 of 104 (permalink) Old 2019-06-18, 03:29 PM Thread Starter
 
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post #4 of 104 (permalink) Old 2019-06-18, 03:30 PM Thread Starter
 
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post #5 of 104 (permalink) Old 2019-06-18, 06:42 PM
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For $36, why bother. Use a VHF antenna designed for VHF.
Presume ur looking for VHF HI and not low band VHF.
https://www.newark.com/stellar-labs/...nna/dp/71Y5462


discussed most recently here:
https://www.digitalhome.ca/forum/186...ml#post3079737

DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.
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post #6 of 104 (permalink) Old 2019-06-19, 08:33 AM Thread Starter
 
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Majortom,

Thanks for the reply. I know there are a few VHF Hi antennas available for purchase.

I just did not want to put this antenna in metal recycling without seeing if it were possible to put it to use as a VHF antenna after modifying it a bit. Seems like a big waste to just toss it.
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post #7 of 104 (permalink) Old 2019-06-19, 09:09 AM
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You have to bear in mind that things like element length and spacing are important factors in antenna design. Both are significantly different between UHF and VHF, so trying to convert that antenna would be more trouble than it's worth.

I haven't lost my mind. It's around here...somewhere...
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post #8 of 104 (permalink) Old 2019-06-19, 10:45 AM
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Quote:
Originally Posted by lenlab View Post
I just did not want to put this antenna in metal recycling without seeing if it were possible to put it to use as a VHF antenna after modifying it a bit. Seems like a big waste to just toss it.
It is possible to modify it, but it would be a major modification. You would be able to use the boom and have to add longer elements for the driven element, reflector, and directors. You would also need a design for the added VHF channel you want. What channel is it?
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Originally Posted by lenlab View Post
My situation may be unique. I am in a difficult reception location. I am only about 30 miles from the NY CITY broadcast towers and at a good elevation (close to 700 feet above sea level). However you can see from the previously posted pictures that my line of sight to the broadcast towers is blocked not only by trees and other obstacles but I am on the back side of a hill facing the broadcast towers.
Where are you located? Can you show us your TVFool report and give us the callsign of the VHF channel you want to add with the VHF antenna?

If you can not measure it, you can not improve it.
Lord Kelvin, 1883
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post #9 of 104 (permalink) Old 2019-06-19, 11:26 AM Thread Starter
 
Join Date: Apr 2017
Location: Randolph NJ 30 miles west of ESB/1WTC
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Another reason I posted this is because there are a lot of experts on this site who just love to tinker and modify antennas. So I gave it a shot thinking someone would have some ideas.

I live in Randolph NJ. The VHF station is NJN VHF 8.1 which previously to broadcast from Montclair as a UHF station 50.1 and was in my LOS to the NY broadcast of VHF stations 7.1(WABC),11.1 (WPIX)and 13.1 (WNET).

It now transmits from Basking Ridge NJ in a completely different direction from the NYC transmitters. So my current VHF antenna does not pick it up.

What I would like to do is remove the first 20 inches of the front of the boom which includes the fist 4 elements to make it a smaller antenna to work with. It is easy to separate as it is held on by a screw. I can show a picture of that in another post as soon as I take it.

Next I would need advice on how many of the remaining elements I would need to keep, their spacing from one another and increase in lengths?

I am open to the possible transformation. It's either that or to recycling center.
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post #10 of 104 (permalink) Old 2019-06-19, 11:27 AM Thread Starter
 
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How would I post the TV fool report?
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post #11 of 104 (permalink) Old 2019-06-19, 11:33 AM
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Quote:
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How would I post the TV fool report?
You can do a report here:

TV Fool

Please post the link to the report that is in bold type near the top of the report.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883
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post #12 of 104 (permalink) Old 2019-06-19, 11:35 AM
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Quote:
Next I would need advice on how many of the remaining elements I would need to keep
None. They're far too short to be useful at VHF. Given the work you need to do to turn that into a VHF antenna, you're better off starting from scratch.

I haven't lost my mind. It's around here...somewhere...
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post #13 of 104 (permalink) Old 2019-06-19, 01:18 PM
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The main boom should be reusable for building a VHF-hi yagi. Start by stripping off all the existing elements and use the boom for building a VHF-hi yagi from and existing design. Check out available designs first as there may be better choices for VHF-hi than a 5' yagi. It might be worthwhile to collapse and store this antenna as-is for future use.
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post #14 of 104 (permalink) Old 2019-06-19, 03:16 PM
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Quote:
Originally Posted by lenlab View Post
I live in Randolph NJ. The VHF station is NJN VHF 8.1 which previously to broadcast from Montclair as a UHF station 50.1 and was in my LOS to the NY broadcast of VHF stations 7.1(WABC),11.1 (WPIX)and 13.1 (WNET).
What VHF antenna are you using now for the NY channels? Will it pick up WNJB if you aim it at WNJB?
Quote:
What I would like to do is remove the first 20 inches of the front of the boom which includes the fist 4 elements to make it a smaller antenna to work with. It is easy to separate as it is held on by a screw. I can show a picture of that in another post as soon as I take it.
You might need the full length of the boom because the VHF elements are about 3x as long as UHF elements and the spacing of the elements on the boom is also about 3x as much for VHF.

I don't know your exact location, so here is a generic TVFool report for Randolph, NJ:
http://www.tvfool.com/?option=com_wr...9038509fbae8d3

This is an image of the generic TVFool report.



This generic report is from rabbitears.info. It should have a more accurate list of channels. WNJN is no longer transmitting; they sold their license in the FCC Repack reverse auction. They are now a Guest on the WNJB transmitter.



https://www.rabbitears.info/market.p...&callsign=WNJB

This is the repack plan for NY:
https://www.rabbitears.info/repackch...=&lss=&status=

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2019-06-19 at 03:54 PM.
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post #15 of 104 (permalink) Old 2019-06-20, 08:18 AM Thread Starter
 
Join Date: Apr 2017
Location: Randolph NJ 30 miles west of ESB/1WTC
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Picture of the VHF Antenna I am currently using and aimed at the NYC Broadcast Towers (Empire State Building and ! WTC) almost due east of me).

Below it is the UHF UDA YAGI Antenna no longer mounted and now looking for a new home or to be modified for use as another VHF antenna.




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