Channel Master FM Filter Question

[KeithAbbott]

My HDHomeRuns are pulling in all of my OTA UHF stations well. My only station on high VHF (Fox, physical channel 7, 177MHz) has a signal strength that is consistently 100%, and signal quality that fluctuates between 70 and 80. I have tried different levels of attenuation going into the HDHR FLEX DUO, to make sure that I am not overloading the splitter within the HDHomeRun. For instance, I put a 10dB attenuator inline, the signal strength dropped to 92 but the signal quality stayed in the 70 to 80 range. I do have a SiliconDust 4g/LTE filter positioned between the power injector (for the amplified antenna) and the HDHR.

Channel Master sells an inline FM filter, I am wondering if I may be getting some sort of constant signal quality issue due to interference with FM station broadcasts. Any thoughts on whether adding an FM filter before the HDHR would boost the signal quality?

[signcarver]

My first thought would be to look at make/model of antenna if you really feel the need as I feel that is an excellent level for physical 7 as the typical high vhf antenna would be geared more to physical 10.

[KeithAbbott]

My antenna is a Televes DAT BOSS MIX UHF-VHF Amplified Antenna (model 149483). So if I'm reading your reply correctly, a signal quality between 70 and 80 is about as good as anyone's going to get for physical channel 7. I'm assuming that is because it is at the very bottom of the high VHF range, instead of the middle of the range like physical channel 10. Strange that the signal strength can be so high, and yet the signal quality is mediocre.

Sure wish Fox was broadcasting on UHF, I probably would not have an issue if that was the case.

[fri1038sd]

Unless you are seeing breakups, 75% signal quality is perfectly fine and nothing needs to be done. Nothing mediocre about it. So long as it isn't bouncing below 50% and symbol quality is a steady 100%, you're good. I have a few stations in the high-50s that are perfectly stable.

You can get 100% signal quality on RF7 - just depends on your local signal environment and what might be causing the background noise and if it can be eliminated.

I added an FM filter recently only because curiosity killed the bank account. I saw RF9 SNR go from 75 to 85%. A tiny improvement on RF8. No change on RF7. Normally vacant VHF-low RF6 saw a huge cleanup. Something I suspect is FM harmonics on vacant RF10, signal strength >60%, wasn't affected. But every OTA experience is going to be different.

[KeithAbbott]

The vast majority of the time, the signal quality ranges from 70-80. However, there have been occasions where it has dipped as low as 50-55, and then the video and audio are affected. Which seems to happen mainly during NFL games (go Lions!). So I figure if I can raise the overall signal quality, the likelihood that breakups will happen should decrease.

I may end up trying an FM filter to see if it makes any difference for me.

[jasonl]

Look up your location on Radio-Locator. Look at the FM stations below 90MHz. Click on the i to see the power level, and then the lat/lon to see the transmitter location. If you have a 100kW station on 89.1 that's half a mile down the road from you, FM might be an issue. However, as with every antenna of that design, your antenna is a much better UHF antenna than it is a VHF antenna. It's better than the average "tack a dipole on to a good UHF antenna" design because of the reflectors, but it also looks like the dipole is smaller than optimal for 7 and that's probably hurting things. If the antenna is out of the weather, take a bit of foil and wrap it around the ends of the dipoles to extend it out to a bit less than 32" tip to tip and see if that helps.

[jamesm113]

As others have said, check your fm-fool.com report to see if there's any nearby stations around 88.5Mhz.

I have had trouble with RF10 and there is literally a low power radio station on 96.5 FM across the street from me (which is the 2nd harmonic of VHF channel 10). My signal quality would never go above 75% without the FM filter. Now, it's hovers around 99-100%.

[KeithAbbott]

However, as with every antenna of that design, your antenna is a much better UHF antenna than it is a VHF antenna. It's better than the average "tack a dipole on to a good UHF antenna" design because of the reflectors, but it also looks like the dipole is smaller than optimal for 7 and that's probably hurting things.

So if I were to decide to get a high-VHF only antenna (in addition to my current antenna), would that maybe boost the signal quality closer to 100%? Since I have several OTA HDHomeRuns, I could dedicate one that is connected to a high-VHF antenna to just Fox channels. Maybe something lilke this: https://www.solidsignal.com/Televes-Hig ... nna-106501. Unless there is a better choice.

[kyl416]

With all the noise interference plaguing the VHF band, it's rare to get 100% signal quality on VHF in urban and suburban locations where things outside of your household like nearby neighbors, street lights, traffic signals, business signs, etc are contributing to the noise.

[jasonl]

If you have room for the 7' boom, the Stellar Labs 30-2476 would be my pick because of having more director elements and a better reflector, and costing less than the Televes.
https://www.newark.com/stellar-labs/30- ... dp/71Y5462

[fri1038sd]

It will be interesting to see if the FM filter changes anything. You can compare with the Live Bandscans in your area at the rabbitears.info website. The dark blue line in the graphs is the signal quality. 70s to near 100 in Linovia and Anne Arbor (guessing you are near Detroit.)

There is another RF7 station in Grand Rapids. It potentially could interfere in certain weather conditions. Check for tropo in the Real Time Maps at the dxinfocentre.com website if it's more than a short burst of degradation.

[goofnroxx]

There is another RF7 station in Grand Rapids.

I am in the Grand Rapids market and I see very similar things to the OP on RF7. Signal strength is good, but symbol quality will seemingly randomly drop off a cliff with the accompanying pixilation and freezing while watching this channel. I have a small Yagi style antenna mounted outdoors pointed towards the broadcast antenna. We also have a channel on RF8 in the area and no such issues exist. Both transmitters are about the same direction and distance from me.

[KeithAbbott]

Here's a link to my signal strength & signal/symbol quality graph from yesterday and a little bit from this morning. The blue line (signal strength), is hiding behind the green line (symbol quality) as they are both 100%. The red line is signal quality, which actually hasn't been too bad for the past 24 hours. As I mentioned earlier, it can dip down into the 50s here and there, with resulting dropouts and artifacts.

https://drive.google.com/file/d/1DoV0ka ... drive_link

[KeithAbbott]

If you have room for the 7' boom, the Stellar Labs 30-2476 would be my pick because of having more director elements and a better reflector, and costing less than the Televes.
https://www.newark.com/stellar-labs/30- ... dp/71Y5462

My antenna is in the attic above the garage, I don't think I could fit a 7' boom in there. It looks like it has a little brother (5' boom) that might fit:
https://www.newark.com/stellar-labs/30- ... dp/48Y8141.

If it seems likely that I could see a 10%-20% boost in overall signal quality, it would probably be worth my time and effort to install the 5' antenna along with my existing antenna (but at least 6 feet away). Here's the latest version of my signal measurements for that channel, this chart is probably more typical of what I get day-to-day:
https://drive.google.com/file/d/1lmnsSO ... drive_link

I'm looking for knowledge-based opinions: should I install a high-VHF antenna dedicated to that station, or will I still be disappointed in the resulting reception? If I'm likely to be disappointed, I may as well stick with my existing setup.

p.s. As in the previous chart, the blue signal strength line is hiding behind the green symbol quality line, signal strength is 100%.

p.p.s. I tried a FM filter; as expected, it did not raise the signal quality.

[ckwsp101_tv]

To manage multipath interference I needed to move antenna to find best location to receive station. A separate VHF antenna may offer better reception with an alternative placement/aiming.
Trial and error activity.