Thanks TVLurker - I will try that. One question, should the antenna be horizontal or would it be better to be slightly tilt to get more of the "edge"?

By my calculations, the top of the Ryan Tower at Camp Fortune is about 2 or 3 degrees up from horizontal. It shouldn't make too much of a difference.


Where do you get the info on the future digital channels? do you have a list that is out yet? I do not recognize some of these.
thanks

Most are from the Industry Canada Broadcast database. DHC moderator stampeder has an easy-to-read web page version of the relevant data -- search for the link.

There are a few stations that are not listed as approved yet (CIVO on channel 30, and CHCH on channel 22), but I'm fairly confident that they'll be on the air by the end of the summer. A CHCH engineer told me by email that they have applied for channel 22. I have no idea why this information does not show up in the broadcasting database yet -- my IC contact has not answered yet.

I might get add a small 4-bay antenna to point to CF if needed.

UHF is less likely to be a problem, so adding a 4-bay may not help you much. What you will most likely need is a VHF-LO Yagi. Optimally this would be a cut channel Yagi specifically for channel 6 (I have a lead on a very limited supply of them at a great price and may organize a bulk order). Alternately you could use a Broadband VHF-LO Yagi such as the YA-6260 (http://www.winegard.com/kbase/upload/ya-6260.pdf) or Y526 (http://www.antennacraft.net/pdfs/Y5-2-6.pdf), but they will be bigger (since they do all of VHF-LO) and won't give as much gain.

Is it better to combine close to the antenna or run a separate co-ax and combine close to the TV?

When using a band combiner (as opposed to a broadband combiner) it doesn't really matter where you put it if you aren't using a pre-amp. When you do have a pre-amp, other considerations come into play.

Last, how do I put my TVFool result to my profile?

When you edit your profile, you can put the link to your TVFool results as your "homepage."

duchaine, so is this a cm-3971 or 3671 ? Your 2 posts titles do not match, looks like it must be 3671.

It's hard to know if you'll need any other antenna if your current one carries the whole UHF/VHF range.

With mine, for example (cm4228hd), I am pointing south and CF is about North-East. Normally you would think this is bad, but the digital stations coming off the back of the antenna are all fine. The analogs coming off the back from CF don't look good at all but i know the signal will be good enough after the transition so I just wait for Aug 2011 before watching those. Do you think you're seeing enough signal for Global in analog now that you think in Aug 2011 the Global digital signal strength will be fine ?

One other thought about duchaine's situation. Most people find an FM trap greatly helps the reception of CIII-TV-6. I am not sure, but the situation may even be worse for him since while he has a 2-edge diffraction for CIII, he may have line of sight to many of the high power FM stations, making the difference in received signal strength even greater.

Duchaine,

I think your antenna is fine. Looks like a good one. It's a receive all VHF / UHF / FM yagi (?)

Everyone mentioned experimenting with aiming the antenna. I agree.

1. ROTOR? But I see no mention of installing a ROTOR.

It's an obvious suggestion... but I'll mention it anyway... I think a ROTOR installation will help do that - and allow you to experiment and aim back and forth - depending on what channel you want to watch.

(Agreed ... since CF is 50 degrees to the side of HC, that is a good thing, and you want to try and steer the biggest side NULL of your antenna at CF, when trying to receive HC channels.)

2. Switchable FM Trap. High Q. If FM is causing trouble, interference, and bad picture with Global, ch 6, Switchable FM TRAP (Agreed). High quality one. "High Q". Steep roll off. Switchable - Trap IN / OUT - so you can experiment ... or FM TRAP "OUT", switched off if you do want to point around, and receive FM (I think your antenna receives FM too).

3. No Pre-AMP. Agreed. I do not think a pre-amp is necessary for your goals. Signals strong enough. A pre-amp may actually introduce other problems and make things more complex.

Duchaine,

Polar Plot for the CM-3671

http://www.hdtvprimer.com/ANTENNAS/CM3671.html

I wrote: "steer the biggest side NULL of your antenna at CF, when trying to receive HC channels"


Best Null appears to be at 90 degrees for your antenna.
(Yagi receives least off the ends of the elements - naturally)

So try this to receive HC channels: in your case Duchaines, point your CM-3671 antenna at 82 degrees (CF) + 90 degrees = 172 degrees to receive HC channels and reject CF channels and reject CF FM radio transmissions.


CF 82 deg......................................................... ...........HC 152 deg
(max null here)

|
|
| CM-3671 ant. point --->
|----------------------------------------| point 172 deg. (20 deg right of HC)
|
|
|

I'm going to go against the crowd and say if Global is not strong enough, trying a cm7777 (on loan like you mentioned) can be a worthwhile experience.

If you keep your 3671 antenna pointed at HC and are getting the CF channels from the back of the antenna where the gain is lower, a cm7777 with the FM trap turned on and the wideband UHF/VHF preamp could help. You'd need to set the 7777 with FM trap "IN" and "Combined" input setting when using just your single VHF/UHF antenna. (Using the Combined input connector...)

By the way, this based on my own experience... Adding a preamp to my cm4228hd improved signal strength for signals coming off the back... which some channels which were sketchy became reliable. All depends what signal levels you are getting now, the 7777 embedded trap (read: blocker) may be a very very nice extra help needed since channel 6 usually gets interference from the FM channels

Duchaine, my original diagram above, has an error.

on your TV Fool, HC is 132 deg to you, (not 152 deg - wrong, my mistake.)

That changes it to: point 40 deg right of HC (not point 20 deg right of HC)

Corrections to diagram underlined and in bold.


CF 82 deg......................................................... ...........HC 132 deg
(max null here)

|
|
| CM-3671 ant. point --->
|----------------------------------------| point 172 deg. (40 deg right of HC)
|
|
|

( I'm using "true", not "magnetic" numbers. Take that into consideration if using a compass to aim, compass = magnetic, small difference)

40 degrees to the right of HC is alot. Much more than the 20 degrees I thought originally. That may cause some issues for UHF channels from HC. Anyway ... experiment, give it a try.

Find an aiming point, somewhat to the right of HC, for all channels, where you reject enough of CF and get suitable results for HC channels.

If it works ... and you find that changing the aim of the antenna is necessary to receive ALL/each of the channels well - CF and HC channels... then consider a rotor.

By the way, I use a rotor, but not for rotating between channels. I only use it for not having to go back to the roof to reorient the antenna ! This way i can tweak my accuracy within 1 degree from the comfort of my home. So i rarely ever use it, but for me not going back to the roof is priceless for the original cost I paid for it.

Thanks to all of you.
I now have quite a few options to try out. I will need to make a matrix of my results.
Because of the temperature over the weekend, I did not go on the roof. A rotor would have been nice and will consider one in the spring.
I should receive my friends CM-7777 this week and will add it to the trials -hopefully next weekend.

Mrvanwinkles, I am not sure if I follow your logic, but I can tell you, that the antenna is actualy about that direction now (about 40deg to the right of HC). I was getting CITY(not Global as mentionned in my initial post) descently after my 10-12 trips up and down, so I left it there. But I did not understand why. To me, pointing directly to a far transmitting antenna, makes more sense.( I will study your posts to understand this) I can't wait to experiment, with an helper in the living room this time, to see what is my best compromise.

Flavoie (and Roger1818), I also like the idea of the pre-amp as a filter, if nothing more. I will set it up the way you suggest. Regarding a rotor, what kind of price and wiring I must look at? Because I am looking at only 2 antennas, I thought that, comes to worst, I will by a small UHF antenna for CF and keep my big one for HC, but again, only experience will tell. I have also started planning to take the big tree at the edge of my property next spring. Mainly to increase my reception, but also because it is treatening the house.

Again, thanks to all of you. BTW, are any of you using a Bell PVR with OTA to record? if so, what is the best/fastest way to record without the EPG?

(about 40deg to the right of HC). I was getting CITY

I am glad to hear that this worked for you, for City-TV ch. from the HC, Herbert's Corner / Manotic transmitter. (? and the other channels from HC like that?)

To get Global, I am guessing / my theory is - that you have to point your antenna directly at the Camp Fortune Tower. 82 deg. But Global is a problem for you for other reasons:
1. The Global Transmitter is lower down on the CF tower - and there is not a direct line of sight (LOS) between your antenna and the Global transmitting antenna. (your TV fool tells us-->) There is a hill or other obstructions directly between your antenna and Global transmitting antenna. This makes power you receive from Global less. And gives you worse / lower quality signal also.
2. Global is on frequency of channel 6. VHF Low - just below / and very near FM band - and therefore you may have interference from powerful FM transmitters also located on CF tower - when you try to receive Global ch6. This may give nothing - no reception of ch 6. or a very poor picture. (Yes, the FM Trap in the 7777 Pre-amp may help with this - but the Amplifier part of the 7777 pre-amp may cause trouble - overload with the other powerful channels and FM signals from CF tower ... which is very close to you.)

All you can do is point the antenna, and try the 7777 & trap - and see what happens.

Good luck and let us know how it goes ...

For the benefit of all of our members and readers, please use English-only in this thread, and French-only in the following thread:

QC/ON - Outaouais, Ottawa, Est de l'Ontario - OTA en français (https://www.digitalhome.ca/forum/showthread.php?t=105999)

Cheers/Salut

I thought that, comes to worst, I will by a small UHF antenna for CF and keep my big one for HC,

I do not recommend buying a second UHF antenna! The UHF signals from CF should be very strong and easily receivable with any antenna and since you also want UHF from HC, combining them will weaken the signals from the big antenna.

You will most likely want a separate VHF-LO antenna however for receiving Global. It would be much easier to combine since there isn't any VHF-LO from HC. Because of your situation you will need one that will reject the strong FM and VHF-HI signals also from CF.

Regarding Duchaine's problem. Another idea came to mind.

Duchaine's TV fool indicates:

- mostly all of HC is UHF, [except for one channel, CHCH TV ind, - ch 11 vhf hi]
- HC is 23.8 miles distant (not too too far, close enough for a loop antenna).
- At 30 ft antenna height shown on his TV fool, he's got a couple LOS and the rest mostly 1 edge from HC.

What about if Duchaine constructs a simple oversized UHF loop (oversized to try and get ch 11 on VHF hi too).
- screens it on one side of the loop to sheild it from all stuff coming from CF
- screens the loop on the back with a separate reflector, placed the right distance back, to add a little gain from the front, and also to reject anything coming from the back.

- mounts it off the side of his tower(?), near the top, on the side opposite CF (the tower steel will add extra sheilding)

-Points the loop correctly straight at HC

Even an oversized UHF loop is not that big, and easy to make.

(ex those steel wire circles that fall off decorative hub caps - I have half a dozen in the basement - collected from the curb - found all around - a little bigger than your average UHF loop)

I think this is an easy, do it yourself test that Duchaine could try.

( screen? 1/2 by 1/2 inch square mesh? sturdy and tight enough.)


Top View:

CF
|
|
x CF direct signal blocked from loop by screen 1 and Duchaine's TV tower.


(Duchaine's)
(TV tower)
------------------ screen 1
|
|
|
|.....O..<---------------------------------------------- HC
| oversized
| uhf loop ant. aim broadside, directly at HC.
|
|
Screen 2
back refl for loop.

( oh ya, separate coax downlead for the loop. do not combine the signals. if the loop works for HC, it can be A-B switched at the TV with the large Yagi - and maybe no need for rotor. Point the large YAGI 3671 at CF, FM trap it if necessary to get all those CF - TV channels. )

Bear in mind that, come August, CHCH-TV-1 channel 11 becomes CHCH-DT-1 channel 22 from Herberts Corners, so don't put too much effort into supporting VHF-Hi reception from Herberts Corners.

Bear in mind that, come August, CHCH-TV-1 channel 11 becomes CHCH-DT-1 channel 22 from Herberts Corners, so don't put too much effort into supporting VHF-Hi reception from Herberts Corners.

Yes, come September, all VHF will be from CF. VHF-HI will not likely be a problem from CF as he has LOS. His big problem will be Channel 6 (also from CF) as he has a 2-edge diffraction and there will be tones of FM interference.

http://www.digitalhome.ca/forum/picture.php?albumid=458&pictureid=3515

While that kind of screening seems like a logical solution, unfortunately rather than acting as a blocker of the undesirable signals it may act as a "tuner" or "reshaper" of the intended reception field, possibly giving unwanted results.

The only time I recommend that sort of screening is for attic-mounted antennas in homes near airports as a means of countering aircraft flutter, with the mesh being above the antenna and definitely not to the side.

If you want a more technical analysis of the screening idea just post a thread in the Antennas R&D Forum showing your diagram.

While that kind of screening seems like a logical solution, unfortunately rather than acting as a blocker of the undesirable signals it may act as a "tuner" or "reshaper" of the intended reception field, possibly giving unwanted results.

Good point! The reflections off the mesh will distort the reception pattern of the antenna. To make matters worse, this distortion will be channel dependent.