Just a comment about unstable AGC comment.
I was wondering if you checked the AC voltage at the amplifier(s) that had the "unstable AGC"?
If an AGC is drifting (on the older equipment), it has many possibilities. Some are:
1.) Bad AGC
2.) Bad Grounding
3.) Scrambled pilot carrier
4.) Processed pilot carrier that had unstable RF input/output (you should only use modulated carrier for pilot)
5.) Bad DC power supply that has excesive AC ripple.
The voltage used in CATV (in older equipment) is either 30VAC or 60VAC QUASI_SQUARE WAVE!!!
This means in simple format...that you must use a TRUE-RMS VOLTMETER to read your TRUE voltage specifications for the CATV equipment used.
I am sure that you have read 67VAC at a 60VAC power supply. Well, the typical error between TRUE RMS and NON-RMS meters is about 7-volts.
So, if you go to a amplifier with an unstable AGC and read 50VAC...you really have 43VAC Quasi-Square. And in many types of equipment, this causes the DC supply to go out-of-regulation and into "Ripple Heaven". The "Ripple" causes the detector circuit in the AGC to drift along with the sinewave it has superimposed piggyback on the pilot DC voltage.
Sorry for the ramble.....lol. Just had to throw my 2-cents worth in. I always had good luck with the old C-COR gear...just had to fix the plant problems it was installed into first.
Good Luck!
Greg
Re: any info on c-cor?? Unstable AGC Comment
Member #: 7190
Registered: 1996-2001
Posted:
483
Name:
Greg Tobin
Name:
Greg Tobin
Company:
Interactive Broadband Technical Services
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HFC Engineer/Consultant
Location:
www.interactive-broadband.com
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Experience:
~45 years
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