OTA: Ontario Parts, Sales, Service, Installers

RF variable attenuators & odd stuff

Although it is not just for OTA, another member just PM'd with an inquiry about where to buy a RF variable attenuator.
I found a little shop in the GTA that carries all kinds of old electronics and they had a bin of them there in July (2008):

AZ Electronics
1750 Steeles Ave. W
Unit 14
905-761-8838

Just W of Dufferin, north side of Steeles

Okay, I'm a Newbie at this.

I'm a civil/structural guy who has spent over 20 years in the tower industry. That being said, I know my steel, but not so much about the electronic side of the industry.

After 16 years of enduring rabbit ears here at Winston Churchill/403, we are making the move to HDTV with a couple of Channel Master antennas.

I plan on mounting a CM4228 to Buffalo and a 4221 to the CN Tower (ordered both of them from the Channel Master website and delivered to my door no problem). Both of the antennas come with baluns, but no pigtail. I plan on getting some RG-11 cables to create about 24" of pigtail off of each balun into a combiner I picked up at The Source. I would put the whole shebang into a weatherproof PVC box and run one RG-11 cable into my basement where I will split the signals to my analogue and HD TV's. I plan on mounting the antennas onto a Wade peaked roof mount assembly with guy wires.

To the experts on this board, does this sound feasible for a clear picture?
One of my concerns is the combiner. Are there good combiners to use?

Thanks.

Hi Tower,

Combining two antenna's is tricky business - and you really have to know what you're doing. There are calculations required to determine spacing between antenna's. You have to have exactly the same length of cable between the two antenna's to the combiner. (Easy enough to do - but don't assume pre-packaged cables are exactly the same so you'll probably want to make your own cables.)

Then you'll need filters and channel traps...

From my research, the results are not guaranteed - other folks here will chime in.

However - I'm at 3rd line and Rebecca and had no problem with my 4221 getting both Buffalo and Toronto. I pointed one of the side lobes towards Grand Island and optimized signal strenth from there - and even though it is a bit weak with a CM 7788 Pre-Amplifier I get great reception.

The front (much more stronger lobe) ends up pointing to the middle of Lake Ontario from my location - but enough of it gets the CN Tower....

From your more easterly location - and being further north - I believe your angle between the two transmitting sites might be even more suitable using this strategy...

Much less complicated... and less expensive...

Thanks Rob,

I was considering your option. During the Olympics, I hooked up my 4228 to some coax sitting around my house and connected it to my analogue TV's one at a time. I hung it on my children's play fort, shooting directly into my neighbour's fence and I still picked up a clearer analogue signal from WUTV, CBC channel 5 and clarity on CHCH like I've never seen before! This all while shooting over the lake.

I asked a friend of mine who is also a broadcast Engineer and he suggested the combining. Ideally, I'd like to try it your way and avoid the need for a rotor if at all possible.

In case my idea does not work, do you recommend any filters/channel traps?
Is a CM7788 preamp easy to come by? Should I order one of those from Channel Master as well? Or would you recommend a different preamp?