AVS Forum banner
1 - 20 of 42 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter · #1 ·
I've got the older-style CM 4221 (4-bay) antenna, mounted in my attic, aimed at an antenna farm 31 miles away, and it has always worked fine, with no channel drop outs, including my two high VHF channels (9 and 11).


I've now added some splitters and additional RG6 quad shield cable so I could connect two other TVs to the antenna. There are two two-way splitters and the longest run of cable to a TV is about 80 feet. I've installed a Winegard AP-8700 preamp to make up for the signal loss due to the splitters and added cable length.


Now, even though they worked fine before for over a year, my two high-VHF channels drop out about every 4 days, usually in the evening for a couple hours. This happens on all TVs, on all the different cable runs.


I know my CM 4221 antenna is mainly a UHF antenna, but it always worked fine for me for high-VHF channels, until I added the splitters and preamp.


I double checked the voltage runs along the preamp, and everything seems to be working fine, and the preamp does boost the signal strength of each channel, usually by 2 or 3 bars out of 10. But could the preamp be contributing to my channel 9 and 11 stations to drop out?


Another question: Since my antenna is in the attic and not on a mast, I mounted the preamp at the bottom of the antenna, on the pole where it would go into a mast. This couldn't be causing any electrical interference on the antenna, could it?


Any advice on how to fix this? I know putting the antenna on the roof would be better, or adding a high-VHF antenna would help, but since it worked before, I was wondering if the culprit is the preamp?
 

·
Registered
Joined
·
23,234 Posts
1) have you tried using the additional TV's/splits without the pre-amp?

2) have you tried using the pre-amp inserted "after" the new/additional splits?

3) have you considered trying a 4-way splitter as opposed to 2-way?

4) are all connectors installed properly?


There are many approaches to diagnose the issue(s). Use process of elimination or introduction to isolate.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #3 ·

Quote:
Originally Posted by Ratman /forum/post/20862981


1) have you tried using the additional TV's/splits without the pre-amp?

2) have you tried using the pre-amp inserted "after" the new/additional splits?

3) have you considered trying a 4-way splitter as opposed to 2-way?

4) are all connectors installed properly?


There are many approaches to diagnose the issue(s). Use process of elimination or introduction to isolate.

1) I tried unplugging the preamp and the signal drops on all channels, but just now I read in another posting that maybe I should remove the preamp and test it that way ... is that the best way?


2) Haven't tried that, since I thought the preamp should be as close to the antenna as possible.


3) Haven't tried that ... would have to run a lot of extra cable to do that.


4) Used a professional compression tool and put on really good quality connectors that the pros use (forget the name) on all the coax cable. All the connectors seem to be on good and tight, but I am new at doing this, so I should double check them. Is there a good way to visually check them ... i.e., I know you have to make sure none of the braiding is touching the main center wire. Anything else I should be looking for?


Also, all the splitters are new ones from Monoprice. Are they typically decent quality?


Thanks for the suggestions on things to check.
 

·
Registered
Joined
·
23,234 Posts
1) no.

2) that's usual. But you had no problems prior to the introductionof new wiring and amp. Too much signal is as bad as not enough.

3) as suggested, use a troubleshooting process. Start from A and work to Z or Z to A.

4) no ill intent... but using a professional tool doesn't guarantee professional results.


Good idea to double check.


I wouldn't suspect the splitters from a quality perspective.


I'd suggest you look into adding a high VHF antenna.

As Mike Holmes would say, "Make it right".
 

·
Registered
Joined
·
325 Posts

Quote:
Originally Posted by Ratman /forum/post/0


I wouldn't suspect the splitters from a quality perspective.

Actually, while I love monoprice, their coaxial splitters are terrible. I replaced my three-way monoprice splitter with a quality Holland and now get three more OTA channels. Dramatic difference.
 

·
Registered
Joined
·
23,234 Posts

Quote:
Originally Posted by walford /forum/post/20863681


Digital TV tuners will not accept a signal if it is either too weak or too strong your amp may be sending too strong a signal to your TVs

Read?

Point #2 in post #5.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #10 ·

Quote:
Originally Posted by walford /forum/post/20863681


Digital TV tuners will not accept a signal if it is either too weak or too strong your amp may be sending too strong a signal to your TVs

Could too strong of a signal be the case even when on my TVs it says the signal strength for my best channels are 7 out of 10 bars, and for my worse channel (9) is 4 out of 10 most of the time, and then every 4 days or so, it drops to 0 and I lose the channel for a few hours?


If it was too strong of a signal, wouldn't my TV's show 10 out of 10 bars?


Also, regarding Ratman's comment, I understand that using a pro tool and pro parts don't guarantee pro results
, but is there a way to tell visually if you have a bad connector connection? All the connectors I put on seem sturdy and tight, and the braiding and sheathing are folded back under the connector and not touching the coaxial's center wire. It is tricky to get the braiding wires and foil stripped just right and folded back, but if it's not done correctly, could that cause only high-VHF channel drop out problems? What is the usual cause of connectors failing ... is it that they become loose or let water in?


And one other question I have for you HDTV experts ... since I can get great reception with no drop outs on high-VHF and other channels when only one cable and TV are connected to the antenna, as I've been doing for 1+ years, does that rule out the antenna as a problem ... or might I still need to add a high VHF antenna?


Thanks everyone for the ideas and advice on what to check ... they are appreciated!!
 

·
Registered
Joined
·
3,281 Posts

Quote:
Could too strong of a signal be the case even when on my TVs it says the signal strength for my best channels are 7 out of 10 bars, and for my worse channel (9) is 4 out of 10 most of the time, and then every 4 days or so, it drops to 0 and I lose the channel for a few hours?


If it was too strong of a signal, wouldn't my TV's show 10 out of 10 bars?

No since the "meters" are not indicating actual signal power. Rather they're showing some proprietary result that is heavily weighted on the quality or decodability of the incoming digital signal.


Run by a Radio Shack and pick up an inexpensive FM filter. Even at retail, they're only about 7 bucks. Catalog number 15-0024, IIRC.
 

·
Registered
Joined
·
19,749 Posts

Quote:
Originally Posted by ProjectSHO89 /forum/post/20864055


No since the "meters" are not indicating actual signal power. Rather they're showing some proprietary result that is heavily weighted on the quality or decodability of the incoming digital signal.

Agreed. Built-in signal meters are misleading. To actually test the signal strength, you need external equipment. Digital is digital. You either get it, or you don't. If you're on the fringe of reception you'll have issues.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #13 ·

Quote:
Originally Posted by ProjectSHO89 /forum/post/20864055


Run by a Radio Shack and pick up an inexpensive FM filter. Even at retail, they're only about 7 bucks. Catalog number 15-0024, IIRC.

My preamp claims it has a "Built in FM Trap to prevent overload from strong local FM stations." Would the Radio Shack FM filter be the same thing, or would that provide an additional benefit?
 

·
Registered
Joined
·
3,281 Posts
The external trap would be in addition to the internal trap, provided the internal trap is engaged.


Just got feedback from a poster on another forum who had a DB8 with an 8700 and had lost reception on a low-VHF and a high-VHF when the pre-amp was added. We recommended he remove the pre-amp and he reported back that the problem went away. You should also try this. Do not unplug the power supply - remove both the amplifier and power inserter completely.


I'd suspect that the problem is that the 8700 is too susceptible to strong signals for your location and is now exhibiting IMD on the VHF band. FM signals are the most common culprit, so suppressing the FM signals is a good start. If possible, exchange the 8700 for either an HDP-269 or an Antennas Direct CPA-19, both of which will tolerate high input signal levels without creating IMD.
 

·
Registered
Joined
·
1,967 Posts
If reception was satisfactory with 1 set connected a Channel Master 34xx series distribution amp would be the best choice IMO. It will deliver a more balanced signal to multiple outlets than a pre-amp. They are very resistant to signal overload as well.


All splits should occur right at the amp for the best results. Splitting the signal further down the line is not advised.


Please you provide a TV FOOL report so we can see what your signal levels look like?


Thx!!
 

·
Registered
Joined
·
797 Posts

Quote:
Originally Posted by Digital Rules /forum/post/20865194


If reception was satisfactory with 1 set connected a Channel Master 34xx series distribution amp would be the best choice IMO. It will deliver a more balanced signal to multiple outlets than a pre-amp.

Not at all. Distribution amps are nothing more than an amp and splitter in one mechanical package. CM's 34xx series is nothing more than a 15 DB amp with a splitter and power supply. Our 4- and 8-way DAs are very similar.

Quote:
They are very resistant to signal overload as well.

Yes, they definitely are since most of them are relabeled CATV drop/distribution amps, intended to boost already strong signals relative to what we often see coming off antenna systems.

Quote:
All splits should occur right at the amp for the best results. Splitting the signal further down the line is not advised.

It's really not relevant where the downstream splits occur unless you're daisy-chaining splits. You can put a splitter right at the output of the amplifier, then run a 100' run or you can make a 100' run from the amp to the splitter. In either case, the signal powers will be identical at either the output of the remote splitter or the end of the 100' coax.
 

·
Registered
Joined
·
325 Posts

Quote:
Originally Posted by ADTech /forum/post/20865646


Yes, they definitely are since most of them are relabeled CATV drop/distribution amps, intended to boost already strong signals relative to what we often see coming off antenna systems.

Is this a good thing? I'm about to purchase a pre-amp with the intention of boosting one station's weak signal. The problem is that every other signal coming in is quite strong already, so I'd like to avoid overload.
 

·
Registered
Joined
·
1,967 Posts

Quote:
Originally Posted by ADTech /forum/post/20865646


Not at all. Distribution amps are nothing more than an amp and splitter in one mechanical package. CM's 34xx series is nothing more than a 15 DB amp with a splitter and power supply. Our 4- and 8-way DAs are very similar.

I respectfully disagree. When supplying 2 or more sets in a mixed very strong/moderately weak signal environment, the CM distribution amp far exceeds what can be accomplish with a Winegard HDP-269 pre-amp with even just a 2-way split. Not sure why, but it has worked quite well in numerous situations for me. The weakest signals are maintained at all 4 splits with the distribution amp, while the pre-amp with post splitting loses some of the weak ones.

Here is an example of one area where the distribution amp far surpassed the pre-amp. The distribution amp preserved stations all the way down to WMPB-29 while connected to a 91-XG & YA-1713. Those are some pretty strong signals in my book.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #19 ·

Quote:
Originally Posted by Digital Rules /forum/post/20865194



Please you provide a TV FOOL report so we can see what your signal levels look like?


Thx!!

Here's my TV Fool report .


As a reminder, it's channels 9 and 11 that drop out occasionally. I get great reception on all other channels in the area, most of which are broadcast from the same antenna farm about 31 miles away.
 

·
Registered
Joined
·
23,234 Posts
Two things to keep in mind:

1) you're using a UHF only antenna for VHF high reception. It may/can work well with a "simple" connection (one run from antenna to TV). Probably marginal, yet acceptible reception for the tuner(s).

2) adding a pre-amp or distribution amp also boosts "noise". Therefore, you've made marginal (VHF high) reception worse with the increased noise.


You can try all of the amps you like, but the bottom line (and easiest) IMHO is to add a VHF antenna.
 
1 - 20 of 42 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top