Quote:
Originally Posted by Tower Guy
Sorry, I missed that the splitter that you had was amplified. The splitter is a very good one, but designed for CATV systems where all the signals are the same level.
Here's it's spec sheet; http://www.channelvision.com/index.php?option=com_virtuemart&Itemid=1&file_id=335〈=en&page=shop.getfile&produ ct_id=254
The output level rating is +23 dbmv assuming 160 channels all with the same level and analog TV. With the 5.5 db typical gain the input rating would be +17.5 dbmv (+17.5 dbmv is equal to -31.25 dbm) Adjusting the spec to two channels yields an input capacity of roughly -7.25 dbm. At that level, the intermodulation products are 60 db below a single carrier. The VHF stations on your TVfool report are -23.3 and -24.1 dbm, but that's average power. The gross peak power on those two stations is about -11.5 dbm (ignoring antenna gain and line losses). The amplifier is very close to saturation.
In an off-air environment amplifiers must be selected very carefully. The distribution amplifier that you have is not optimum for your application. The suggestion of a AP4700 preamp removes the possibility of VHF overload. The distribution amplifier should be removed from the system. |
Tower Guy , you are 0 for 1 so far. I substituted the amplified distributor with a passive two way splitter and the signal got worse. The tuner card software shows the signal strength so here are the comparison:
With the distributed amplifier, only two ports used and the rest are terminated:
Channel(real) ..Signal Power ... Signal Strength
6 .....................15 dB .......... 45% (can't watch)
8 .....................31 dB .......... 100%
10 .....................30 dB .......... 100%
30 .....................29 dB .......... 100%
40 .....................19 dB .......... 72% (stutters)
18 .....................25 dB .......... 97%
19 .....................31 dB .......... 100%
With a passive two port splitter:
Channel(real) ..Signal Power ... Signal Strength
6 .....................6.1 dB .......... 22% (can't watch)
8 .....................25 dB .......... 100%
10 .....................27 dB .......... 100%
30 .....................24 dB .......... 90%
40 .....................8.3 dB .......... 30% (can't watch)
18 .....................20 dB .......... 72%
19 .....................25 dB .......... 95%
Looking at the drop in signal, it corresponds to the 4 dB gain the amplified splitters claims it provides.
I ordered the pre-amp you recommended but I will try it with my current antenna. I let you know if it makes any difference.
Anyone else has any other suggestions?
Thanks from San Diego