Same stack to combiner to FM Filter to Preamp, yeah real channels to magnetic point, still no WMYD 20, even last night at a close to 50 channel peak where I was pulling ION & WADL-DT, I find this really bizarre.

WMYD is not real channel 20, it is real channel 21 and VIRTUAL channel 20.1. If you are going to use a virtual channel number, please use the decimal form to avoid confusion. Giving the callsign, as you just did, is even better.
So do I. There is a reason; we just haven't discovered it yet. They might be having transmitter trouble, or you might have interference to that channel.

In conversation I always refer to the channel number the station is identified with rather than the real (assuming its different), I understand the difference, regardless I tried the direct 20.1 point of 29 degrees magnetic this morning & I was surprised that I lost all but 6 channels of 36 (with the 22 degree point), I know its directional but that is a really an extreme blackout point, even local WNWO-TV 49 (24) dropped which I get with a 22 degree point with preamp even though its 98 degrees magnetic, anyhow WMYD is still a mystery.

I refer to the channel by its real channel number because

1. it is the real channel number that determines the antenna needed.
2. the real channel number is always listed on the report, but the virtual channel number isn't always listed.
3. sometimes two channels will have different real channel numbers, but the SAME virtual channel number.

You might understand the difference, but the way you state it isn't clear.

Using the callsign avoids that ambiguity and uncertainty.

Why don't you call the WMYD station engineer?
This is the time of year for tropospheric propagation when you will receive channels that you will not usually receive.

I might if I find the time & it nags me enough, none of the channels received in the sweet 22 degree range are highly unusual for any time of the year in this general location in the last 4 or so years of OTA usage. I find this selection to be the norm rather than the exception if not perhaps a bit lower than average from the sandwich days of DB4e with a working preamp at my old Apt a couple years ago. Improved stability for WDIV has its costs I guess.

WDIV on real channel 45 has adjacent channel interference from WUPW on real channel 46. A tuner is not expected to reject adjacent channel interference that is more than 33 dB stronger. WUPW is 49.6 dB stronger than WDIV.

5.4.2 Adjacent Channel Rejection

The receiver should meet or exceed the thresholds given in Table 5.2 for rejection of first
adjacent-channel interference at the desired signal levels shown above the columns therein.

https://forum.tvfool.com/attachment....8&d=1434754883

When you overload a tuner with local signals, it makes reception of weaker signals more difficult, because spurious signals are created in the tuner from IMD (Intermodulation Distortion) that damage the weak signals.

WUPW -29.1 dBm + 13 dB ant + 18 dB preamp = +1.9 dBm; tuner overload

ATSC Recommended Practice:
Receiver Performance Guidelines

Document A/74:2010, 7 April 2010

RECEIVER PERFORMANCE GUIDELINES

5.1 Sensitivity

5.2 Multi-Signal Overload

Sometimes the combiner you are using has problems. What happens to WMYD when you connect the UHF antenna to the tuner with and without the preamp, bypassing the combiner?

UHF Ant > FM filter > grounding block > tuner

UHF Ant > FM filter > preamp > grounding block > power inserter > tuner

Which FM filter are you using?

In short this is why I opted for a more directional antenna to address this, there has been improvement.

This crossed my mind but I would have to take down the whole stack to access the combiner & I don't have another afternoon to forfeit doing that right now, too much other house stuff to do, recabling ate a whole afernoon yesterday I had planned for other work.
The FM Filter was bought at radio shack a 3-4 years ago, not sure of the model, it resolved the issue I had with WTOL 11 breakup I had at the time.

Good, a more directional will help that because they are in different directions.
Also good.
Understood

It's not a factor at this point since I recabled to a separate rotor connection but a FYI to anyone who might want to attempt a single cable connection with the ROTR100 from ProBrand support: " Channel Master Spartan series Pre Amps draw less current so 0068DSB, 0268DSB are good ones and 0065DBS and 0265DSB come without the power supply so may be a cost saving as well.. I am not sure if they still have these lower voltage, lower current draw units but that is where to check."

I also contacted WMYD & they verified that there have been no changes on their end so at this point I have conclude that the loss of DB4e from the stack or the combiner are the cause, not a lot of time to verify this in the next couple weeks.

That sounds like the same list I got from them 5 or so years ago when we were selling that rotor. Only problem is that all of those Spartan models were discontinued some 5+ years ago. That makes it a pretty tough proposition to score one unless you get lucky.

Double rescan
 

Double rescan

Have you tried a double rescan? It is possible that the tuner memory has become corrupted by, for example, WHNE on real channel 20 at the same azimuth.

https://www.google.com/?gws_rd=ssl#q=fcc+double+rescan

That got me wondering about the UHF antenna change. It wouldn't be gain, so maybe it is a slight change of antenna location or the form factor of the antenna.

I did a terrain profile that shows how the curvature of the earth blocks the direct signal and causes it to graze the surface and be subjected to ground clutter interference.

http://forum.tvfool.com/attachment.p...1&d=1475689113

The ground clutter interference will cause scattering of the signal so that it presents a non-uniform wave front to the antenna. This non-uniform field makes the location of the antenna very critical, because there will be hot spots and cold spots.

http://forum.tvfool.com/attachment.p...5&d=1466633825

http://forum.tvfool.com/attachment.p...6&d=1446858514

http://forum.tvfool.com/attachment.p...1&d=1475692853

It is also possible to have a non-uniform field in the vertical direction. Moving a UHF antenna a little as 6 inches up or down can make a difference. That would be easier for you to do than moving it in a horizontal direction. I wonder how the DB4e would do now?

http://www.hdtvprimer.com/antennas/siting.html

I was having trouble receiving CH 42 because my antenna was facing the wrong direction. The signal was strong enough, but the signal quality was poor; the tuner was not able to pick it up during a scan.

http://i496.photobucket.com/albums/r...pscp5alww7.jpg

As you can see, the top of the signal is not very flat, which probably indicates a multipath reflection problem. That's not surprising, because the antenna is aimed in the opposite direction and only reflections off the objects in front of the antenna are picked up; there is no direct signal from the transmitter.

I went across the street and setup a 2-bay UHF antenna, my Sadelco DisplayMax 800 signal level meter, and a CM7777 (original) preamp. I was able to get a nice scan and a stronger signal with the antenna aimed at the transmitter for CH42.

http://i496.photobucket.com/albums/r.../CH42setup.jpg

Interestingly, when I moved the antenna a few feet left or right, without changing the height or azimuth, there was a big difference in the signal strength and scan quality. This is most likely because of the tree line in front of the antenna about 200 ft away which created the non-uniform field.

I was able to get a nice scan and a stronger signal with the antenna aimed at the transmitter for CH42.

http://i496.photobucket.com/albums/r...pstck7kriy.jpg

My 8-inch Audiovox TV in the car was able to pick up CH42 WCVE; the 22-inch Sony was too big to bring along.

http://i496.photobucket.com/albums/r.../CH42found.jpg

Great explanation of multipath by Rabbit, who else?
 

Rabbit,

I have to hand it to you, that was the best explanation I've ever seen of multi path. I for one didn't get it to be honest. I think I'm getting the hang of what multipath means now.

Using those illustrations sealed the deal for me. Is Ken Nist still active?

Thank you for your kind words; I'm still learning so that I can make clear explanations.
I have learned a lot from Ken's website.
http://www.hdtvprimer.com/
His website is still up most of the time, but he doesn't add to it anymore and has only retained the essential parts. I don't know about the "active " part. His ham license is still active, and was renewed in 2013:
http://wireless2.fcc.gov/UlsApp/UlsS...?licKey=621708