CABL Forum - Re:870MHz S-A need answers

I agree with Sweep Daddy (I like the name). The return IC on most of the good amplifier to-day can handle 4 CW carrier at around 63 dBmV out. Be careful on the return laser, this is where the high level return signal will cause most of the problem.

Andy Lamarre

>I am in agreement that the customer sets the procedure.
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>Having said that, I appreciate the correction. The comments were well reasoned and make perfect sense. Padding the ingress on the input wasn't something I had considered, nor did I consider the improvements in isolation that immulating the fwd path losses would provide. Excellent info, and I thank you.
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>Franmc, avoid fallacy, it's the sign of a weak mind. I would only point out, that in years of sweep contracting, not a single S/A system has used a pad on the input of the return. I am on a S/A project right now, and this sytem isn't padding the input. Don't get me started on OEM specifications that don't translate to the field.
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>I admit to a certain jerking of the knee, in my comments, if you were offended I apologize for any discomfort I may have cause you. I didn't imply an insult towards you. I merely commented without due consideration, ( I knew I was stepping in it, but I was sure that there would be no hesitation to correct me, if I blew it)to your post. It was an honest opinion, nothing more or less.
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>Best regards,
>Michael O'Conner
>
>>Mr. Daddy;
>>After two years at S-A teaching people how to install and maintain GainMaker products, I feel pretty confident that I know what I am talking about.
>>However, if you still don't believe me, [and assuming you can read] look at the "Installation and Operation Guide" [S-A# 593161] on page 3-43. There are instructions followed by a nice little chart that details the return input pad selection for amplifiers with internal DC's [or Auxilary Signal Directors as S-A calls them]. I can email or fax a copy of the page if you like, just ask.
>>As for optimizing the return path, any pad selection is made at the design stage. This is done by design software that looks at "worse case" situations, and allows the designer to select the best pad value for the particular feeder leg. As SkopeJW said, modems and set-tops need to be running at a high output level to keep them as far above the noise floor as possible. Generally, the higher the better.
>>Hope this helps.
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>>
>>>"Mimick the forward path losses"? Huh????
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>>>Why would the return network need to realize losses of the actives internal forward network? The return signal is being distributed from that leg back through the network. Unlike the the forward signal that has to be regulated by the DC-8, to balance its value in regards to its fixed originating output, to accomplish the desired downstream inputs. The return signal is being injected at various locations, through various passives, with the modem having variable output capability to accomodate all of this, allowing its signal to hit the first amplifier with as low an output as possible.
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>>>By padding the input to the return chip, you are merely adding additional attenuation the sending modem must overcome in order to hit the level it needs to provide to the return amplifier in that active.
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>>>Driving the modem output higher than would otherwise be necessary. Increasing noise to the first Return amp.
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>>>I can see no reason to pad the input to the return, in order to immulate internal forward losses.
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>>>As to padding fwd input to make output. S/A has variable multi/amps for various design needs. "Given the appropriate amplifier" and ONLY in this consideration, will the desired input levels be met by the input pad necessary for the desired output.
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>>>Just shoving pads to make output is baaaaaaaaad advice cowboys.
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>>>;)
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>>>>Splicer life is correct.
>>>>Also be aware of the return input pad requirements for the GM Duals. You must pad the return input to match any internal DC value used on the forward output. For example: If an internal DC-8 is used, the return input tap leg needs to have an 8 pad installed and the thru leg a 2 or 3 pad. This procedure mimicks the forward path losses on the return path. It is very important to do this. If no DC or two way is used, 0 pads are installed.
>>>>In our design procedure, we will also "adjust" the return input pad value incremently until we have optimized each leg for optimum output levels at the various return devices. This really helps a customer at the end of a long distribution line.
>>>>If anyone would like additional information, feel free to contact me.
>>>>
>>>>
>>>>>
>>>>>pad just the input for the desired output and go. these gainmakers are the nicest equipment i have worked with to date. GREAT amps!
>>>>>
>>>>>>We are having a problem with setting up the forward levels
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Re:870MHz S-A need answers