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mh2721 7-Jun-2018 12:04 AM

Problem with 1 channel on combined antenna's
 
TV Fool report: http://www.tvfool.com/?option=com_wr...90389c6f5ecc01

I have 2 antenna's in an attic. One is a Antenna's Direct DB8E antenna pointed west toward Baltimore. And the other is a Antenna's Direct Clearstream 4MAX pointing north/north east toward Philadelphia. The antenna's are about 10-12 feet apart.

I am combining these antenna's with this: https://www.solidsignal.com/pview.asp?p=2512
which then goes to a winegard lna-200 preamp, then on a 100ft coax to 1 tv.

When both antenna's are connected to the combiner WTXF (Fox) real channel 42, completely loses signal. It's gone. All other channels from Baltimore and Philly are ok.
After much tinkering, I found that if I leave the DB8E (Baltimore antenna) off the combiner, Fox returns.

(WTXF) Just 4MAX on combiner: Signal Strength is 70 with a SNR of 21-22
(WTXF) Both antenna's on combiner: Signal Strength and SNR = 0

What if anything can I do to get WTXF Fox with both antenna's on the combiner?

Thanks for any help.

ADTech 7-Jun-2018 10:47 AM

The problem is occurring because both antennas are picking up WTXF (check the DB8e by itself to verify) and the signals are effectively cancelling(destructively interfering with) each other resulting in lost reception. This is very common side effect of combining antennas pointed in different directions with a simple two-port reversed splitter.

The "solution" is to ensure that the the DB8e is not picking up WTXF. Be aware that whatever you do now, it's probably going to be short-term only as Philly repacks next summer and Baltimore the following spring. Each stage of the repack will bring the opportunity for new problems and I have not attempted to "look forward".

Potential remedies, you'll have to figure out which are viable:

1. Adjust the DB8e so it does not pick up the problem station. You may be able to move it around so the path towards Philly is blocked by whatever is available.
2. Isolate or screen the DB8e so that the signals from Philly do not reach it.
3. Install a channel 42 trap (custom ordered from a specialist)on the DB8e's output. Will likely sacrifice WUTB. Guaranteed to be obsolete when WTXF moves to channel 31.
4. Optimize the location of the C4M so that the signal strength of WTXF is increased. Add the optional reflector for starters. Get it out of the attic, if necessary.
5. Use an A-B switch or multiple tuners keeping the signals isolated from each other.


There's a good reason that, whenever anyone contacts us regarding this type of scheme, I have always advises them that it's going to be an experiment and that the results cannot be foretold. You're trying to accomplish with a $5 part the same result that a cable company will spend hundreds of dollars per channel to achieve.

Good luck.

Nascarken 7-Jun-2018 1:30 PM

Or a good amp that does have a vhf&uhf in and you don't have problems like that or
2uhf in good luck.

ADTech 7-Jun-2018 5:58 PM

Quote:

Originally Posted by Nascarken (Post 59904)
Or a good amp that does have a vhf&uhf in and you don't have problems like that or
2uhf in good luck.


Neither will solve his particular issue.

mh2721 7-Jun-2018 10:45 PM

Thanks adtech.

I will start with putting a reflector on the 4max and moving the db8e around. I tried the db8e by itself, still pointed toward baltimore and yes it does pick it up, but not well. Screen is pixalated and there are dropouts.

I forgot about the repack so if what you suggested does not work, I am going to go back to just the db8e with the panels pointed 1 toward philly and 1 toward baltimore. There are drop outs at different times during the day this way though.

Thanks again.


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