From what I know about driver amps, there really is no correct input level, just how much performance do you need to get out of your headend.
With the specs on the amp being in European PAL standard for 96 channels, I'm only guestimating the levels for these numbers. Loading it with 110 NTSC channels, you might be able to run it a little hotter.
The reference output level of 103 dBuV converts to 43 dBmV, and thats for 96 PAL channels. At that output, with 17 dB of gain, you'd have 26 dBmV at the input. The distortion figures of -60, -66 (CTB, CSO) would be worst case, so as your input levels decrease, your distortions improve twice as much. CNR at the 43 dBmV output would be about 75 dB. CNR degrades 1 for 1 as input levels decrease.
Reduce your input to 23: CTB= -66 CSO= -72 CNR= 72 Output 40 dBmV
Reduce your input to 17: CTB= -78 CSO= -84 CNR= 66 Output 34 dBmV
Reduce your input to 14: CTB= -84 CSO= -90 CNR= 63 Output 31 dbmV
I would run it with about 17 dBmV input, the performance numbers you'll see should be OK, and 34 dBmV should get you enough signal to feed 32 transmitters. Play it safe and test your CNR, CTB and CSO when your done.
Good luck.
Re: Need help with Headend Amp Input drive level
Member #: 19319
Registered: 1996-2001
Posted:
143
Name:
Lorne
Company:
major MSO (3rd namechange in 5 years)
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Lead System Tech
Location:
Virginia
Personal:
60-ish
Experience:
~31 years
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