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-   -   Presumed FM interference (http://forum.tvfool.com/showthread.php?t=14415)

ADTech 1-Jun-2015 7:20 PM

An infomercial, no. It's a setting of expectations when a given tool that is at hand is known to not be the best suited for the job.

If the OP wishes to give it a try, then he should do so since all he's spending is time and effort. It's his choice to see if it will help or not but, if it doesn't, there is no definite conclusion about it one way or the other.

rabbit73 1-Jun-2015 8:02 PM

Quote:

I know that, but the OP already has the RS unit. Why not try it first??????? Is this an informercial?
He already tried it. Weren't you paying attention?

And if he tried it again, and it didn't work again, what would you suggest that he do next?
Quote:

Originally Posted by dbseeker (Post 51408)
.....All fm traps (most recent a Winegard FT 3000) have been tried and in multiple series with no effect.. NO amp is used and cable run at 50 feet.

It couldn't possibly be an infomercial, because I said use a HLSJ instead of the AD or RS filter.

I have selected the best tools for the job without consideration of brand, which is what engineers do and marketing guys don't. I selected the Juice preamp, not because it is made by AD but has excellent proven resistance to overload from strong signals. Do you know of a better one?

No static at all 1-Jun-2015 8:19 PM

No, just saying I have used a RS trap where all the charts & graphs indicated it likely wouldn't offer enough attenuation, but it worked like a charm. Sometimes things work in the real world that don't on paper.

Just like I have a 2005 Corolla that the EPA rates at 27 city/35 highway. I never have see a tank below 40 MPG, even regularly commuting in ugly DC traffic. Currently averaging about 45-46 MPG in the warmer weather.

Like everything else, YMMV.

No static at all 1-Jun-2015 8:25 PM

Quote:

Originally Posted by rabbit73 (Post 51425)
He already tried it. Weren't you paying attention?

Oops, I didn't see where he tried it again. My apologies:)

rabbit73 1-Jun-2015 8:29 PM

No problem. I have been known to miss a post and have been called down.

At least you are trying to help.

Sometimes a good idea comes from an unexpected direction, so I try not to reject it right away.

dbseeker 2-Jun-2015 12:37 AM

Great discussion.
To quote Bones on Star Trek, "For Godsakes Jim, I'm only a doctor not an engineer!!"
I have at my disposal a Winegard FT 3000 and a Radio Shack fm trap
that I have tried separately but not in tandem with no effect but a reduction in all channel signal strength.. I also have a winegard 8275 with trap and the RCA preamp with trap. Also have a AD CPA 19 and various and sundry Terk and RCA inline amps with no traps.
All amps produced worse signal strengths on all channels and with 50 feet of coax to the tv, so I just eliminated them.
Tried using the analog to digital convertors at both locations and still no signal on the Y10713 but signal on the RCA 751 so tuner sensitivity not the issue.
Will get a couple of HLSJ and give them a shot.
The question comes to mind if it is a second harmonic on RF7, why is the bigger antenna affected and not both? I believe these radio stations operate 24/7 and since I see no pattern to the reception issue, the changing of transmitting KW( if that is the case) seems to have no effect on the reception pattern. I am remiss in not having a grounded system. This setup is at my 87 y.o. Mother's house and while OTA has become a novice hobby of mine(obsession?), I will correct that also.
As always, the level of expertise found here is extraordinary and I can't praise everyone enough.

rabbit73 2-Jun-2015 12:47 AM

Thank you for the background information and the kind words.

Please let us know the results on this same thread.

Quote:

changing of transmitting KW
That is done for AM transmitters in the broadcast band, because the signals go farther at night.

No static at all 2-Jun-2015 12:49 PM

Quote:

Originally Posted by dbseeker (Post 51439)
Tried using the analog to digital convertors at both locations and still no signal on the Y10713

Are any of the boxes Zeniths?

Quote:

Originally Posted by dbseeker (Post 51439)
The question comes to mind if it is a second harmonic on RF7, why is the bigger antenna affected and not both?

Could be FM, or just the difference in where the antennas are mounted. Once you try the HLSJ(s) we will know better as they will eliminate any FM concerns.

Tower Guy 2-Jun-2015 2:07 PM

I'd check the balun next.

rabbit73 2-Jun-2015 3:22 PM

Quote:

Originally Posted by dbseeker (Post 51408)
About one year later, I have been struggling with real channel 7.....As an experiment today, mounted an RCA ant751 about 8 foot below the antennacraft Y10713 to a separate tv tuner and picture watchable with mild pixilation on rf 7 with no reception on the Antennacraft. Again rf 9 receivable on both antennas.

The FM interference was stronger from the Y10713 because it has more VHF gain than the 751.

dbseeker 11-Jun-2015 12:48 AM

Update--installed 2 hlsj's in series and low and behold signal strength returned to normal range on the LG but no picture. With tweaking of the aim of the Y7 10 13 and a presumed signal quality improvement, picture returned with rare pixilation from mild wind and trees. Was able to reconnect the RCA preamp with increase in all channel signal strength.
While all posts celebrate the RCA preamps resistance to overload, I believe this fm signal hit its Achilles heel.
Now as editorial comment, for the extra $1.98 that an hlsj costs, why not incorporate them in manufacturers harness / balun/ connectors that a hi VHF antenna is shipped or manufactured with to increase customer satisfaction and success rate.
If we didn't follow this type of philosophy in medicine, the cemeteries would be much larger.
Again, greatly appreciate everyone's expertise.

rabbit73 11-Jun-2015 2:05 AM

1 Attachment(s)
Thanks for the update with the good news. It's good to hear when we get a tough one right.

Quote:

With tweaking of the aim of the Y7 10 13 and a presumed signal quality improvement
Tweaking aim while monitoring signal quality (SNR and errors) is the best way to do it. The technique works best and is most sensitive when the signal is weak and close to the "Digital Cliff."

http://forum.tvfool.com/attachment.p...1&d=1433989061

Aiming an Antenna for Best Signal Quality
http://forum.tvfool.com/showpost.php...19&postcount=7


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