Comments on: Passive TV Repeater http://www.matthewsworkbench.com/passive-tv-repeater/ Wed, 04 Jan 2012 14:47:40 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Russ Walsh http://www.matthewsworkbench.com/passive-tv-repeater/comment-page-1/#comment-8370 Russ Walsh Thu, 20 Oct 2011 04:36:51 +0000 http://www.matthewsworkbench.com/passive-tv-repeater/#comment-8370 Did this back in 1971, in the Cariboo region of British Columbia, Canada. Picked up channel 6 from Kamloops on one antenna, used a preamp, then ran the signal about 100' over a rock bluff in order to provide isolation, and pointed the second 'ransmitting' antenna at Clinton. Reception was perfect, in color, all over town! Cost? $150. Works for UHF or VHF. At the time Clinton had only one other TV channel, so the doubling of TV service was much welcomed - by the community. Sadly, not by the DOC bureaucrats (Canadian 'Department of Communications') who shut the thing down after 1 month. The town was forced to spend $18,000 to get the signal back using standard repeater technology. The reception wasn't any better; and the town was out $18,000 - in 1971 dollars = about $60,000 today. The same concept was used more famously in a town called Nakusp, BC, on the Columbia River. Nakusp had no TV at all. No radio, either. At least until night time skip kicked in during the evenings. It was discovered that channel 4 - KXLY - Spokane, could be received with good signal strength on a 7,500' mountain. There were NO Canadian stations available at all. So a passive repeater was installed to provide Nakusp with its first ever TV reception. It worked superbly - until the Canadian bureaucrats moved in and tried to shut the system off. Since the operation merely 'reflected' channel 4 from Spokane down into the valley - still on channel 4 - the bureaucrats were skating on thin ice. More bureaucrats were hired - even supervisor bureaucrats, whose mission in life was to take away Nakusp's only TV station. The battle went on for years. Much paperwork was generated - the life blood for bureaucrats. In the end the passive repeater was granted an exemption and allowed to remain operational. Since Saddle Mountain 'repeater' site was inaccessible by road and could only be reached via a 20 mile hike straight upward, and since there was no power available at the site, deep cycle batteries were installed late in the fall just before the snow moved in. The system then ran for the entire winter on these batteries, which lasted until spring, when they were replaced by fully charged ones. Now THAT's dedication! The DOC bureaucrats, however, used helicopters to reach the site. The total DOC expenditure on trying to shut Nakusp's passive repeater down was $5.2 million. The cost of the repeater? $250. Batteries included! On a technical note, the selection of both receive and transmit antennas is entirely dependent upon local circumstances. In order to increase the signal strength of a distant channel, high gain, highly directional antennas are best. However, if highly directional antennas are used for the retransmission, the signal will be focussed more narrowly. The transmit antenna depends upon how wide an area is to be served. Check the antenna's specs for 3 dB beamwidth. 3 dB beamwidth is the aperture at which the transmitted signal has reached half power. So if an antenna has a 3 dB beamwidth of 40 degrees, 20 degrees in each direction from boresite will produce a half-power signal. And all antennas have lobes, which will produce signal anomolies. Passive repeaters are a great and inexpensive way to extend TV signals into unserved nooks and crannies. They work equally well for digital as well as analog signals. One further thing - if the receive site is capable of picking up multiple channels, either use a broadband receive and transmit antenna, and broadband preamp, or use a single channel antenna, single channel preamp, followed by a bandpass filter for the desired channel in order to filter out undesired channels, otherwise you'll end up 'repeating' all of them. Did this back in 1971, in the Cariboo region of British Columbia, Canada. Picked up channel 6 from Kamloops on one antenna, used a preamp, then ran the signal about 100′ over a rock bluff in order to provide isolation, and pointed the second ‘ransmitting’ antenna at Clinton. Reception was perfect, in color, all over town! Cost? $150. Works for UHF or VHF. At the time Clinton had only one other TV channel, so the doubling of TV service was much welcomed – by the community. Sadly, not by the DOC bureaucrats (Canadian ‘Department of Communications’) who shut the thing down after 1 month. The town was forced to spend $18,000 to get the signal back using standard repeater technology. The reception wasn’t any better; and the town was out $18,000 – in 1971 dollars = about $60,000 today. The same concept was used more famously in a town called Nakusp, BC, on the Columbia River. Nakusp had no TV at all. No radio, either. At least until night time skip kicked in during the evenings. It was discovered that channel 4 – KXLY – Spokane, could be received with good signal strength on a 7,500′ mountain. There were NO Canadian stations available at all. So a passive repeater was installed to provide Nakusp with its first ever TV reception. It worked superbly – until the Canadian bureaucrats moved in and tried to shut the system off. Since the operation merely ‘reflected’ channel 4 from Spokane down into the valley – still on channel 4 – the bureaucrats were skating on thin ice. More bureaucrats were hired – even supervisor bureaucrats, whose mission in life was to take away Nakusp’s only TV station. The battle went on for years. Much paperwork was generated – the life blood for bureaucrats. In the end the passive repeater was granted an exemption and allowed to remain operational. Since Saddle Mountain ‘repeater’ site was inaccessible by road and could only be reached via a 20 mile hike straight upward, and since there was no power available at the site, deep cycle batteries were installed late in the fall just before the snow moved in. The system then ran for the entire winter on these batteries, which lasted until spring, when they were replaced by fully charged ones. Now THAT’s dedication! The DOC bureaucrats, however, used helicopters to reach the site. The total DOC expenditure on trying to shut Nakusp’s passive repeater down was $5.2 million. The cost of the repeater? $250. Batteries included! On a technical note, the selection of both receive and transmit antennas is entirely dependent upon local circumstances. In order to increase the signal strength of a distant channel, high gain, highly directional antennas are best. However, if highly directional antennas are used for the retransmission, the signal will be focussed more narrowly. The transmit antenna depends upon how wide an area is to be served. Check the antenna’s specs for 3 dB beamwidth. 3 dB beamwidth is the aperture at which the transmitted signal has reached half power. So if an antenna has a 3 dB beamwidth of 40 degrees, 20 degrees in each direction from boresite will produce a half-power signal. And all antennas have lobes, which will produce signal anomolies. Passive repeaters are a great and inexpensive way to extend TV signals into unserved nooks and crannies. They work equally well for digital as well as analog signals. One further thing – if the receive site is capable of picking up multiple channels, either use a broadband receive and transmit antenna, and broadband preamp, or use a single channel antenna, single channel preamp, followed by a bandpass filter for the desired channel in order to filter out undesired channels, otherwise you’ll end up ‘repeating’ all of them.

]]> By: Tom Terrific http://www.matthewsworkbench.com/passive-tv-repeater/comment-page-1/#comment-6200 Tom Terrific Sun, 12 Sep 2010 13:07:29 +0000 http://www.matthewsworkbench.com/passive-tv-repeater/#comment-6200 Broken link on passive TV repeater but I like the concept. I'm up on a mountain and my friend is down in the valley can't get HDTV reception. Would like to beam him down HDTV for Super bowl parties... etc. I was thinking of using old Satellite dishes to make it more directional. Let me know if there are more ideas in this area. Thanks in advance. Broken link on passive TV repeater but I like the concept.
I’m up on a mountain and my friend is down in the valley can’t get HDTV reception.
Would like to beam him down HDTV for Super bowl parties… etc.

I was thinking of using old Satellite dishes to make it more directional.
Let me know if there are more ideas in this area.

Thanks in advance.

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