Televes Hi-VHF Yagi

[Ben Zonia]

Without a filter, services in the 230 MHz region may also cause receiver induced intermodulation interference, which products may end up on Channel 9, and may be intermittent. You also could also put a quarter wave trap in for those frequencies to see if it improves it. That's why antennas for VHF High made for the US and Canada cut off sharply above 216 MHz.

[Ben Zonia]

Comparing an antenna that costs $60 and can be easily used indoors—which is where I need to use the antenna—to an antenna that costs $240 and is essentially impossible to use indoors or even in an attic is not a particularly apt comparison.

I used to climb towers and work on sloping roof tops, but now an 8-foot step ladder is as high as I climb.

No accurate modeling of the Televes Hi-VHF yagi can occur without knowing the element spacing dimensions, which are not given in their literature or in my remarks. So the outcome of such a project is hardly going to be credible.

The man that does this modeling measures the elements and spacings and boom construction himself, or gets them from the manufacturer's engineers. There is also another man nearby that has an antenna test range who could do the testing you say is impossible.

Look, I said it was a DECENT antenna, but it is not without problems.

[jimh]

The model of the Televes antenna in question would certainly be a poor choice for those desirous of VHF low reception over a significant distance. They do have other models that might work decently for that, though.

I don’t think Televes has any dedicated Hi-VHF antennas that would be better than this classic seven element yagi. They have some big combination Hi-VHF and UHF antennas that might be interesting to compare with.

Televes is paying attention to the USA market, as they have redesigned some (but not all) of their UHF antennas to reflect the latest re-packing to fewer UHF channels.

[jimh]

There is also another man nearby that has an antenna test range who could do the testing you say is impossible.

You have invented something I did not say. I said accurate modeling must include element spacing. I said nothing about testing a real antenna on an antenna test range. However, I will say something about antenna range testing:

Antenna test ranges are often problematic. You need a large area free from any radio-conductive or radio-absorbent structure that could affect the antenna under test. And precision test gear.

But you bring the Winegard big antenna and I’ll bring the Televes, and let’s see the comparison. Where is the test range located?

[Ben Zonia]

If you live near the Branch of the Rouge River in Bingham Farms, Longley Rice prediction for CBET 9 suggests shadowing. You can Zoom way in to your exact location.

https://www.rabbitears.info/contour.php ... 000&site=1

[jimh]

On the predicted signal map linked above, my location is in the yellow shaded area, indicating “hard indoor” reception for CBET-09.

I am trying to do exactly that: receive CBET-09 with an indoor antenna, albeit a 7-element Hi-VHF yagi is a bit more than the typical indoor antenna.

Now that I have been getting solid signals from CBET-09 well into the usual completely-lost-signal conditions of hot weather and trees in full foliage, I thought readers might be interested to hear how well the Televes Hi-VHF 7-element yagi was working for me.

Ironically, there may only be one more Stanley Cup game to record this year, and then my interest in watching CBET will, like its signal, fade until October, when I hope Hockey Night In Canada returns.

[Ben Zonia]

CKLW-TV had a much better signal from the Riverside Dr. tower. Too bad they couldn't have just put a tower or building up there somewhat taller than the Ren Cen. But moving was also part of a Canadian government restriction of Canadian stations appealing to a US audience and advertisers that began with the RKO General ownership and The Big 8.

It's far enough away now that earth curvature and terrain shadowing are much bigger factors, made even worse by the fragile digital signal cliff.

[k8jd]

When I read the antennas under test were "inside an attic"......Well I made up my mind . THAT'S the PROBLEM.

[k8jd]

CKLW-TV had a much better signal from the Riverside Dr. tower. Too bad they couldn't have just put a tower or building up there somewhat taller than the Ren Cen. But moving was also part of a Canadian government restriction of Canadian stations appealing to a US audience and advertisers that began with the RKO General ownership and The Big 8.

It's far enough away now that earth curvature and terrain shadowing are much bigger factors, made even worse by the fragile digital signal cliff.

Yes! they moved the TV tower WAY out West of the City, to beter serve the counties over there , across the river.

[Ben Zonia]

A good rule of thumb, ancient but still useful, is that the Line Of Sight distance at ground level is D=SQRT(3 X H/2), where D is the distance in Miles and H is the antenna height in Feet. So for the CBET/CBE-FM/CBEW tower, roughly 670 feet tall, which is about 30 miles from 48025, the LOS would be about 31.5 miles. From the old Riverside Dr. location, 48025 is only about 18 miles. So we are on the edge of LOS at near ground level from the new location. This would also be influenced by a partially blocked Fresnel Zone, which would cause additional signal losses, and more variation of the signal strength with time. This formula does not take into account intervening terrain and obstructions.

[Ben Zonia]

When I read the antennas under test were "inside an attic"......Well I made up my mind . THAT'S the PROBLEM.

I see that an outdoor antenna is not an option for this person. That is a major problem. Not only is there signal absorption from walls, but reflections off those walls that affect the pattern of the antenna. Also, height of the antenna greatly affects effective gain. One model shows a 10 dB increase going from 6 feet AGL to 20 feet AGL.

[jimh]

When I read the antennas under test were "inside an attic"...

I do not understand where in this thread you read about antennas that were inside an attic. Please explain what you are referring to.

[jimh]

...[CBET} they moved the TV tower WAY out West of the City, to beter [sic] serve the counties over there , across the river.

If you are referring to CBET formerly CKLW, the antenna move was not to the West of Detroit or Windsor. The antenna location moved from downtown Windsor to the Southeast, inland quite a ways. This was to better serve the communities east of Windsor, not west.

[jimh]

I see that an outdoor antenna is not an option for this person. That is a major problem. Not only is there signal absorption from walls, but reflections off those walls that affect the pattern of the antenna.

The antenna that is the TOPIC of this discussion is not blocked by any walls in the signal path. The antenna looks directly out a large window in the heading to CBET. If anything, this helps the antenna because the walls surrounding the antenna--if they indeed attenuate any signals--are then blocking any interfering signals from getting to the antenna.

To get back to the actual topic here, the Televes Hi-VHF seven element Yagi antenna has been working very well at its intended purpose: providing a watchable picture and sound from CBET in a difficult location and being used indoors.

[jimh]

I see that an outdoor antenna is not an option for this person.

There are two aspects in play here.

Federal regulations cover outdoor antennas for reception of television signals, and provide everyone with the option to use an outdoor antenna, including me. There are some limitations, which I will discuss later.

In my individual case, I am not interested in installing a rooftop antenna. This is due to two factors. First, the results with the Televes Hi-VHF yagi antenna being used indoors demonstrate I do not need to go to the bother of an outdoor antenna. I am quite happy with the signal being delivered by the Televes antenna from CBET-09.

Second, I am not willing to work on slanted roof tops at any height, particularly on the roof of my current home, where I would be working about 30-feet above the ground.

Further, the FCC regulations about antenna size are a bit ambiguous because they talk about a diameter of an antenna, which seem to be a reference to a parabolic dish antenna for satellite reception. Exactly what dimension of a seven-element yagi antenna would be its diameter dimension not clear. A closer review of the FCC opinions on this topic reveal that the often cited dimension of 1-meter is not applicable to non-satellite dish antennas.

A good source of information about the FCC regulation, known as the Over-The-Air Reception Devices or OTARD rule can be found at

https://www.fcc.gov/media/over-air-rece ... vices-rule

Quoting from the FCC's webpage:

The rule applies to certain antennas, including...TV antennas..... The rule prohibits most restrictions that: (1) unreasonably delay or prevent installation, maintenance or use; (2) unreasonably increase the cost of installation, maintenance or use; or (3) preclude reception of an acceptable quality signal.

Later on that webpage the FCC clarifies the concept of the antenna dimensions.

Q: What types of antennas are covered by the rule?

A: The rule applies to the following types of antennas:

...(3) An antenna that is designed to receive local television broadcast signals....

In this regard, no dimension limitation is specified.

Under these guidelines, about the only basis for a valid restriction on use of an outdoor antenna being necessary would be a challenge to the nature of the signal from CBET-09 as being "local." However, this could easily be overcome because there are other local television signals on Hi-VHF channels that could be cited as the local signal that was being received.