Y10 7-13 VHF antenna

[Erickson54]

How can I tune my 10 element 7-13 yagi to optimize channel 9 (186-192 MHz). I am 73 miles from the tower. I get channel 11 (198-204 MHz) very well and channel 9 puts out a stronger signal, same tower location and I do not get a viewable picture. I am using a CM 777 preamp. Can I lengthen/shorten elements? I have a old VHF antenna I took down that is 170" long that I used when the signal was analog, should I try this again? I have lately read that gain is secondary to capture area. And without capture area a preamp is not doing the job. The capture area of my old antenna is huge compared to the 7-13. The Wade VIP 306 and 307 SR sounds like a good VHF antenna also.

I would appreciate any direction on this

John

[NN2E]

Hi John,
Yes, you can adjust the antenna for channel 9 but the channel 11 performance may suffer. You might do better with a frequency specific antenna (one that is designed for channel nine) if all you are interested in is receiving that one station.
Now...there are a LOT of other factors involved with reception at that frequency / distance. How high are your antennas? What is your terrain like?...flat?, hilly?, trees?, buildings?...anything in the antenna environment can have an effect on reception. Is there another channel 9 anywhere around which could be causing interference to the one you're looking for? Propagation changes all the time so, sometimes you will receive a station with no problem, and other times, you won't get anything.
73, Ed NN2E
Owner / Operator - Murphy's Law Test Site & Thunderstorm Proving Grounds

[Jim Thomas]

Something else Ed didn't mention. The 2nd harmonic of FM occurs between channel 7 and channel 9 and its been discovered that DTV channels on 7, 8, and 9 suffer from any of that type of interference.

As Ed suggested, the easiest way to remedy a VHF DTV signal situation is to use a channel-specific antenna.

[Robert Grant]

Something else Ed didn't mention. The 2nd harmonic of FM occurs between channel 7 and channel 9 and its been discovered that DTV channels on 7, 8, and 9 suffer from any of that type of interference.<snip>

Actually:

FM = 88-108 MHz

2nd harmonic of FM = 2(88-108 MHz) = 176-216 MHz

Channel 13 = 210-216 MHz

The second harmonic of FM affects channels 7 through 13.

(the fact that it only covers the upper 4MHz of channel 7 is not very important, strong RF in any part of 174-180 MHz can harm digital channel 7 reception).

[Erickson54]

I do want to get ch 9 &11. Will angling the elements toward the tower help? I can get thin wall alum tubing that I can slip over the existing elements to lengthen them. Can I tune out ch 7 & 8 and 12 & 13?Only trees in the path. The transmit signal is stronger for ch 9 but get 11 better and both towers are next to each other. I thought the y10-7-13 would work well and is not bad just looking for better:confused: Should I have my CM777 preamp FM trap (IN or OUT)? It is set to VHF only not combined. The VHF is 5' below the Televes Dat 75 UHF antenna. I have been advised to tilt the Dat 75 up to try and get better UHF reception. Looking at the design I am wondering if the lower beam of the three is interfering with the ch 9 VHF antenna? With certain propagation and Tropospheric condition I can get ch 9 on my UHF antenna. I know this because I only have my UHF connected the last couple weeks.:confused: This happened when it was very foggy in winter here in Wisconsin. I received 28 channels as far as 250 miles away....

John


Hi John,
Yes, you can adjust the antenna for channel 9 but the channel 11 performance may suffer. You might do better with a frequency specific antenna (one that is designed for channel nine) if all you are interested in is receiving that one station.
Now...there are a LOT of other factors involved with reception at that frequency / distance. How high are your antennas? What is your terrain like?...flat?, hilly?, trees?, buildings?...anything in the antenna environment can have an effect on reception. Is there another channel 9 anywhere around which could be causing interference to the one you're looking for? Propagation changes all the time so, sometimes you will receive a station with no problem, and other times, you won't get anything.
73, Ed NN2E
Owner / Operator - Murphy's Law Test Site & Thunderstorm Proving Grounds

[NN2E]

Jim makes a good point about FM interference...with my old CM 7477A pre-amps I had a rash of FM interference, on channels 8 & 9, from one of the local gazillion-watt FMs. I'm now using the CM 7777 pre-amp, with the FM trap switched on, (I don't DX FM) and I don't have any more trouble. You might start there before contemplating any surgery on the antenna.
73, Ed NN2E
Owner / Operator - Murphy's Law Test Site & Thunderstorm Proving Grounds

[Erickson54]

Sorry, I am not a RF guy. "FM trap switched on". I think :confused:the setting on the mast preamp is "in or out". Is ON the the same as IN? Or OUT means keep FM signals out?



Jim makes a good point about FM interference...with my old CM 7477A pre-amps I had a rash of FM interference, on channels 8 & 9, from one of the local gazillion-watt FMs. I'm now using the CM 7777 pre-amp, with the FM trap switched on, (I don't DX FM) and I don't have any more trouble. You might start there before contemplating any surgery on the antenna.
73, Ed NN2E
Owner / Operator - Murphy's Law Test Site & Thunderstorm Proving Grounds

[NN2E]

You'll want the FM trap switched to the "IN" position to activate it.

[Erickson54]

Thanks


You'll want the FM trap switched to the "IN" position to activate it.

[Erickson54]

My VHF antenna is 5' below my UHF. The VHF would be 28' above ground. In my signal path I have trees then the lake and then more trees. No other environmental issues. Underground wires, and only neighbors 200-300 feet away. There is another FOX network (75 miles) but is not channel 9, it is virtual channel 22 and is azimuth of 4degs. Channel 9 is a azimuth of 219. No other VHF channels in this range would interfere as far as I can tell. See channel attachments. Appreciate any more thoughts.



Hi John,
Yes, you can adjust the antenna for channel 9 but the channel 11 performance may suffer. You might do better with a frequency specific antenna (one that is designed for channel nine) if all you are interested in is receiving that one station.
Now...there are a LOT of other factors involved with reception at that frequency / distance. How high are your antennas? What is your terrain like?...flat?, hilly?, trees?, buildings?...anything in the antenna environment can have an effect on reception. Is there another channel 9 anywhere around which could be causing interference to the one you're looking for? Propagation changes all the time so, sometimes you will receive a station with no problem, and other times, you won't get anything.
73, Ed NN2E
Owner / Operator - Murphy's Law Test Site & Thunderstorm Proving Grounds

[davenlr]

The VHF is 5' below the Televes Dat 75 UHF antenna. I have been advised to tilt the Dat 75 up to try and get better UHF reception. Looking at the design I am wondering if the lower beam of the three is interfering with the ch 9 VHF antenna?

John

Hi John. I am using the EXACT same configuration as you. The DAT75 should be pointed at the horizon. If that happens to be higher than its mounting location tilt it up a bit. If you are on a hill, tilt it down a bit.
It has the extra booms of elements to capture the signal to the main boom.

I havent noticed any pattern alteration from having the VHF yagi under it. That should be the first thing you notice.

You COULD trim the Reflector and channel 7 and 8 elements shorter, which should add some gain on channel 9, while retaining channel 11, but if you arent getting any signal at all, I really dont think thats going to help. Stacking two of them might, if you set the spacing for channel 9. That would give you the best chance at getting it, other than a separate channel 9 antenna.

Dave