AVS Forum banner
Status
Not open for further replies.
1 - 6 of 6 Posts

·
Registered
Joined
·
218 Posts
Discussion Starter · #1 ·
I live less than a mile from the HD towers here in SF. I was not able to get CBS at all until I got a cheap Rat Shack attenuator.


I have the attenuator turned all the way to MIN and ABC is rock solid at 100% but CBS is still inconsistent.


Are there differences in attenuators and should I look for another one ? It's almost as if for CBS I need to tune it down even more. Can you stack one attenuator after another ?
 

·
Registered
Joined
·
2,463 Posts
Quote:
Originally posted by ny888
I Can you stack one attenuator after another ?
Yes you can stack.

You will have level variations and the closer station maybe too high of a signal for you STB to handle.


Dave
 

·
Registered
Joined
·
3,993 Posts
Is there some reason for NY888 to believe that just his digital channel 29 is too strong, but not his digital channels 19, 24, 30, 45 and 57? At one mile from the transmitters, you could install a fixed 20dB attenuator pad which you could buy for just a few dollars, and still have plenty of signal strength on all channels. Radio Shack attenuators are just as good as anyone's. These are very low technology items. I think they make a 6dB and a 12 dB, so you could use one of each or two twelves. I "stack" attenuator pads nearly every day when I balance the strip amplifier inputs in multifamily dwelling headends. My off-air signal levels are often well over 40dBmv, but I like my strip amps to have inputs of about 20dBmv, and my heterodyne channel converters to have inputs of about 10dBmv.


There is no such thing as a 560-566Mz "notch filter". Cable companies use notch filters to obliterate visual carriers on analog channels by about 50dB or more so as to make those channels unwatchable, but even if you could obtain a cable channel 80 (558-564Mz) notch filter, it would notch 559.25Mz and weaken just the lower edge of your channel 29 digital waveform. This would not help. Microwave Filter could custom-tune a channel 80 band reject filter to instead perfectly reject channel 29 for about $2,000, but then your channel 29 would become too weak, and believe it or not, even that premium-grade reject filter would wreak havoc upon your broadcast digital channel 30.


If you wanted to weaken just channels 29 and 30 by about 25dB, you could order a ChannelMaster UHF channel 29 or channel 30 Jointenna and deliberately install it incorrectly, using just the "all channels" and "TV" ports and terminating the channel 29 or channel 30 port. Basically, the "all channels" circuit is a weak band-reject circuit that does a fairly even job of attenuating the target channel and the one above it and the one below it. One bad thing about the ChannelMaster Jointennas is that they are not shielded and if you are just one mile from the transmitter, enough signal might leak in through the plastic case to corrupt the desired signal.


If you cannot get all six of these digital signals to lock using the same attenuator pad, and if all six of the transmitters are in the same general direction from you, then you more likely have an antenna problem in addition to a signal level problem. What are you using for an antenna and where is it situated?
 

·
Registered
Joined
·
218 Posts
Discussion Starter · #6 ·
My antenna is a Radio Shack indoor double bow tie UHF and it is sitting in my closet.


I'll try to find another attenuator and stack them or get a 20db one and see if that helps.


The RS attenuator (Cat.#: 15-678) I have doesn't actually say how many db it is.
 
1 - 6 of 6 Posts
Status
Not open for further replies.
Top