CM3016 OTA in attic picked up CBS but not now from roof!

[Vaidy]

I live in Westchase and thanks to Dan(mgd2win)'s suggestion, I bought a CM3016 from Lowe's and went up my attic. Alas, as I have 1 extra room on the 2nd floor, my attic is cramped and my antenna was probably picking up lot of noise - I didn't receive some channels, such as WUSF & UPN 44. However, I did receive CBS, which would be to the rear of the antenna. So, after gaining confidence that no more hurricanes are expected here, I moved my antenna to the roof 2 weekends ago - BTW, I couldn't collapse the spans and used all my skills in getting it out of the attic asis!

Anyway, after verifying that I was directing the antenna in the right direction, I now receive every OTA channel clear, EXCEPT CBS! I am sure that the (rear) reflector spans are killing the signal from the tower in Hollywood.

I am not sure I want to get another antenna and a jointenna, but want to experiment with either adjusting the antenna direction - kind of a compromise - or even removing a reflector span, or adding a extra piece of wire or slim tube to the antenna to pick up CBS.

Does anyone have any suggestions?

[jaymer]

nice article here on antennas:
http://www.hometheatermag.com/accessories/156/index2.html

and a list of various CM antennae
http://www.warrenelectronics.com/Antennas/Chmaster_ant.htm

i've seen a settop Silver Sensor pickup CBS from Rocky Point, so hard to believe yours can't do it now. thats a bummer.
how about spinning it around to point to CBS and see if the others can come off the back? You think yours is getting "blocked" to the rear, but some antennas pick things up at 180 degrees just fine.

my Yagi, a CM 4248, gets CBS from way down here, but only when i'm pointing at it... but i carelessly spin it around and get it close to the direction and its fine... so i don't think its go to be "right on" directionally for you.

unsure about these other tweaks you speak of (wire, slim tube, etc).

jaymer...

[Vaidy]

Jaymer, thanks for your response.

Believe me, I too was surprised since Westchase is much closer to the CBS tower than others in the Riverview area. Maybe the CBS channel's signal strength is too low now for the OTA receiver, as the antenna cable (about 75 feet) is hooked to the outdoor cable connection, as opposed to the previous shorter connection to the indoor splitter in the attic!

I'm going to attempt to remove the UHF reflectors (at least a couple of tubes) and see if that makes a difference. I'll keep you posted.

[brennt]

I live down the road from Westchase in Countryway. I had the same problem with CBS. I never could get the results I wanted with one antenna, so I went the route of using a jointenna. Both antennas are in the attic and I have an amplifier for each. I have a strong signal now on all channels. Its been working great for almost a year now.

I never tried outside with one antenna, so maybe that would work for you. Also, have you tried or considered using an amplifier?

[Vaidy]

Brennt,
I did think about getting an amplifier, especially since the cable length from the antenna to the outside connection point may be too long. My last RadioShack omni antenna had a pre-amp. However, since I had the power unit outside the house, right at the outdoor connection box instead of near the receiver, it got burnt during one of the storms last month. So, I am not exactly keen on getting an amplifier!

I am not sure how correct I am, after having studied Electronics Engineering 20 years ago and never having worked in that line(!), but I have been reading up technical info all along and am confident I can tweak my antenna to pick up CBS from the back side. If I can't, I'll continue to use my rabbit antenna on top of my entertainment center and maybe turn it around to pick up a couple of stations!

[Vaidy]

Guys, I have great news! I was just checking the reception yesterday morning, as my neighbor Dan (mgd2win) wanted to test his HD receiver with my antenna and ..viola...there was CBS coming bright & clear! I didn't touch a thing - antenna is still as it was last week. Isn't it weird? Its probably the weather, for all I know!

Anyway, I just wanted everyone to know. So, my experiments with my antenna have been shelved indefinitely!

[jaymer]

well, i have to say i'm glad your CBS issues are fixed... i don't think i've tuned them in OTA in 6+ months, if not more. next time i can though, i'll spin it around and see what its looking like nowadays from down here.

[brennt]

Come to think of it, it has been a while since I have tuned to CBS as well. The last thing I remember tuning in OTA on CBS was some half-time wardrobe malfunction... but that's another topic.

Vaidy, glad to hear you are picking up CBS now.

[Vaidy]

I figured out last evening what happened to the CBS channel reception waffling and I owe it to others to share it!

First, you might ask what was I doing on the roof if I was was picking up CBS? Good question. The answer is that on Wed evening, my loving wife mentioned that we were no longer picking up PBS (Ch 3), or USF (Ch 16), or Ch 44, while CBS was fne. I was stupified! Of course, I had not told her that when I had installed the antenna on the roof over a week ago, I had dropped one of the mounting nuts which was part of the clamp holding the antenna on the pole! At that time I had thought that because of the shape of the clamp, and if I ensured that the single nut was tight enough, the antenna would stay! What I had not thought about was nature! Specifically, birds! When birds sat all over the antenna rods, or the main beam, and when they flew away, they caused the antenna to swing slightly. It must have swung a little to the East! That's why after the initial challenge with picking up CBS from the rear of the antenna direction, I started picking it up last Thu.

Last week I had gone to Lowes to buy a replacement nut and had first picked up the wrong size - when I had gone up the roof last week, the antenna had not moved. I had picked up a larger size nut and had gone up the roof last evening to put it and that's when I noticed that the antenna was pointing due East, a shift of about 20 degrees! That's why I could pick up CBS, but not PBS or USF anymore!

Anyway, when I first corrected the direction to point towards Riverview, CBS went blank! That's when I connected the sequence of events and then shifted the antenna about 10 degrees Eastward and viola! Now I receive CBS, PSB, USF and all other channels!

..And that's the rest of the story! 8O

[jaymer]

ahhh... a loose bolt and the birds!!!
funny :lol:

[Floyd]

If anyone is interested, one of my suppliers special orders a bay-area special antenna that has the VHF elements cut at the proper length to receive the stations in this area. The main UHF/VHF antenna is designed to accept a flat lead cable from the second antenna in the package, which is cut to receive Ch-10. The way you set it up is to aim the ch-10 antenna at Tarpon Springs, and the main antenna at Boyette. Then you connect the 300-ohm flat lead between the two antennas and use the included matching transformer(balun) on the second set of wingnut terminals for the coaxial downlead into the house.
The ch-10 antenna elements are all the same length, which might not be optimum for the ch24 HDTV signal, but if it is aimed in the right direction it should work better than any single antenna system. The special antenna comes in three versions. The main antenna is the same in all versions, but the second ch-10 antenna comes in 3, 6, and 10-element versions. The furthur you live from Tarpon Springs, the more elements you require.
If you live in a direct line between the antenna farms, then you may pick up enough ch-10 signal from the rear of a single U/V antenna to work with.
The antennas are about 50-70$, and I usually have a couple in my warehouse.
I have considered cutting some of the leading elements to the proper length for ch-24 and doing some before-and-after measurements on my RF signal meter to see if there is any difference in the collecting ability of shorter elements. Antennas have some "channeling" or "directing" elements, so I'm not sure if just cutting some of the elements would actually capture or focus more of the UHF signal back to the capture elements. Any guesses? Another thing, how do I determine the element length for ch24 UHF? Divide the frequency by the speed of Light, or what?