RECOMMENDED AMPLIFIERS TO ADD HD CHANNELS TO HEADEND - AVS Forum
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post #1 of 4 Old 07-01-2013, 06:31 PM - Thread Starter
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HI GUYS!, I'll need some recommendations to complete my most recent task.
The corp. I work for, just acquired an old hotel with a 29 Ch Headend system (dish), with the analog channels modulated from 2-30.
We want to add local ch, and those will be received in digital quality, by the existing 250 Tvs.
Now we have the modulated channels amplified by 1 Blonder Tounge STK NO in the headend room, and 3 other Blonder Tounge ACA 30-550 in the 6th floor that I assume retransmit the signal through the building in 3 zones.
I want to move the actual channels to a higher location so they won't interfere with the locals (lot of channels in the Tampa area between 2-30) and combine the modulated channels with the locals (from antenna) in order that all can be scanned by every Tv in the building.
I really will appreciate any assistance suggesting the type of amplifiers, (assuming I can't use the current ones) that I must use in order to keep the good quality of the current signal, and add 30 or 40 new local ch directly from the antenna.
Thanks in advance.
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post #2 of 4 Old 07-02-2013, 05:44 AM
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Assuming that you're trying to incorporate Tampa off air (I'm psychic), you have a nice clear antenna path to thirteen full powered transmitters, and all of those signals will be within about 8dB of the same signal strength.

Four of them are VHF, on channels 7, 10, 12 and 13, so you will need to move your analog channel 7-13 programming, as well as your channel 22 and 23, to vacant channels just above 30.

The other nine are on UHF channels ranging from 19 to 47, spanning 500 to 674 MHz, so you can't use the amplifiers you are using now. Replace the amplifiers with ACA-860s. and roughly balance the UHF signals so that they are about ten dB below the output of your analog ones, but make sure that you change the signal meter settings when you go back and forth between your modulated satellite channels and your off-air digital ones. If you are pushing your ACA amps to maximum output at present, you might have to reduce the analog signal levels by about 3dB from where they are now if adding these digital signals winds up overloading them. Off the top of my head, ACA amplifiers typically can put out about 5dB less than the much more expensive BIDAs, so an ACA with a 30 channel analog load can probably be set to about a 45dB per channel output level, and so of you add these 13 digital signals, you might be safest to turn the ACAs back to 42dB measured on the analogs, if that still gets you adequate power to your TV sets.

You will need to do a little pre-filtering to mitigate interference from the off-air signals. At the very least, you should use a UHF/VHF band separator, commonly called a UVSJ, on your antenna downlead, and you should get an inexpensive midband reject filter, called an A-I filter, to put on the VHF line to keep your cable/satellite channels 14-21 clean, and you should also use a high band/low band separator, commonly called an HLSJ, on the VHF line to wipe off any interference that your antenna might be picking up on channels 2-6, if you choose to keep analog programming there.
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post #3 of 4 Old 07-02-2013, 07:46 AM
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What will you be using for TVs? Most hotel TVs have locked down menus and make it impossible for guests to change channel plans from cable STD to FCC broadcast, so you might have to "transcode" the digital broadcast signals to "cable QAM" channels. If you have LG TVs, there is usually a way to mix and match analog cable and broadcast digital channels.

There is a very affordable piece of hardware you can get from North American Cable or elsewhere for probably under $2,000 that will transcode eight of the channels for about the same as it would cost to transcode two broadcast channels using Blonder Tongue AQT transcoders. Some TVs, when set on "cable STD" will allow you to tune your four broadcast VHF digital channels but not your UHF ones, so if your TVs are capable of that, then you can use one, eight channel transcoder for eight of the UHF channels while distributing your four VHF digital channels in their native form.

If you do transcode the broadcast signals to QAM, you will be able to use the ACA 30-550 amplifiers.
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post #4 of 4 Old 07-02-2013, 12:32 PM - Thread Starter
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Thanks a lot.
All Tvs are LG, few weeks ago I ran a test, and picked up a lot of digital ch, only with the major problem of those low channels interfering.
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