I want to now address your original concern about damage from overload:

THREE TYPES OF OVERLOAD

There are three types of preamp or tuner overload, in order of increasing signal strength:

1. The strong signals almost cause enough IM distortion to interfere with the reception of weak desired signals, but the spurious signals are at or below the noise floor. This is the point that holl_ands uses in his preamp charts to obtain max SFDR (Spurious Free Dynamic Range). No damage will happen.

As the strongest signals continue to increase in strength, more of the weaker signals are damaged until you reach:

2. The strong signals cause overload to the preamp or tuner that makes it impossible to receive any signals. No damage will happen. The strongest signals are still there, but they can't be decoded because the IMD products have damaged them so that they contain more errors (high BER....bit error ratio/rate) than be corrected by the FEC (forward error correction).

3. The signals are so strong that the input transistor is toast. You are not likely to encounter OTA signals that strong, unless you live next door to a high power transmitter and you have your high gain antenna aimed at the transmitter's antenna.

As a general rule, tuners can tolerate stronger signals than preamps before overload. The difference in strength is approx. equal to the preamp gain.

You will find the preamp chart by holl_ands here:
http://imageevent.com/holl_ands/files/ota

Scroll down to Modified solid signal Chart Comparing Preamps - RevB
It doesn't list all amps, but it gives you the general idea.

He also has a DTV Preamp Signal Overload Calculator - Rev M that calculates Max Input Signal to Maximize SFDR (Spurious Free Dynamic Range).

There is also a system noise figure chart.

And now to put some of your numbers into an estimate, I will use the guidelines from ATSC A/74:

ATSC Recommended Practice:
Receiver Performance Guidelines
Document A/74:2010, 7 April 2010
http://www.atsc.org/cms/standards/a_74-2010.pdf

5 RECEIVER PERFORMANCE GUIDELINES
5.1 Sensitivity
and from ADTech:
http://forum.tvfool.com/showpost.php...3&postcount=31
As you can see, ATSC says that a tuner should be able to handle a signal as strong as -5 dBm and provide satisfactory reception. ADTech has calculated that the signal into your Roamio is under -20 dBm, which is 15 dB weaker.

for more than one signal ATSC says:

5.2 Multi-Signal Overload
Your signal is also weaker than that.

In my previous post about THREE TYPES OF OVERLOAD, a -5 dBm signal would fall between type 1 and type 2 overload, but closer to type 2.

When I was experimenting with my Apex DT502 digital to analog converter box just after it came out, I connected two preamps in series between the antenna and the Apex. When I looked at the monitor, there was no signal on the screen. At that time I didn't know as much about overload as I do now, so I didn't understand what was wrong. It was type 2 overload causing complete loss of reception.

The signal from the antenna was +20 dBmV, which is the way my SLM (signal level meter) measures signals, or equal to -28.8 dBm. The gain of the first preamp was 25 dB, which brings us up to -3.8 dBm. The second preamp gain was 15 dB, which is +11.2 dBm into the tuner. The tuner was not damaged. I haven't tried type 3 overload because I don't want a toasted tuner.

My newest TV is a SONY KDL32R400A. Using a splitter to send a signal to the TV and my SLM, I measured the signal level at 100 on the Diagnostics Screen signal strength scale and it was +40 dBmV, which is equal to -8.8 dBm. The engineer who designed the circuit must have been reading ASTC A/74.

In this country engineers use the symbol dBm for signal power; antenna installers and cable guys use dBmV. Other countries use dBμV (note the little tail on the u which means "micro"), which is dB microvolts. It's also signal power but its reference level is defined in microvolts. The conversion factor between dBmV and dBμV is 60, so 40 dBmV is equal to 100 dBμV, which is what the Sony engineer was thinking. 100 on the signal strength scale equals 100 dBμV.....nice!

I then inserted a variable attenuator (using the method described in the link in my signature) and brought the signal level down to dropout, which was about -85 dBm and noticed that the units on the signal strength scale were equal to about 1 dB. So, I was getting a TV and a signal level meter for the price of a TV.

My older SONY KDL22L5000 signal strength reading never gets up to 100 no matter how strong the signal. The reading is derived from the AGC (Automatic Gain Control that controls the sensitivity of the tuner) voltage. The newer SONY must have a different type of circuit, perhaps an RSSI chip like in cell phones which gives you strength in bars.

I had a chance to measure another R400A, and it gave me the same reading at 100 on the signal strength scale.

I think I'm going to "sit" on this for a little while and observe seeing if I notice any patterns, etc.

While I do that, I would like to know if I decide to try to put the 91XG on the second floor peak what mounting equipment would I need to do that? It seems like when I had run a TV Fool report at different heights that somewhere in the 50 foot range made KRBK line of sight. I'm not sure if the 2nd floor peak meets that requirement or not, but it is still worth a consideration.

I was also wondering what are some of the better 7-51 antennas? I"m not sure I will be going that route but would like to know just in case.

I would also like to say thanks to both of you for your assistance and input to this point. It is greatly appreciated!

The simulator calculates that the KRBK signal path switches from 1-edge to LOS between 105 and 110'.

However, given that the resolution of the digital elevation model used for the simulator may easily have 5 or meters of vertical error and the cell in which it places each elevation for the complete signal path evaluation is either a 30 or 100 meter square, it's far from a precision calculation.

An LOS signal path is not a requirement for solid reception (but it sure helps) and most people who use antennas rely on paths that calculated to 1-edge or 2-edge paths. The important thing is to get the right antenna into a spot that happens to coincide with a signal that's "good enough". Goldilocks, if you will.

I think I may have been getting that calculation mixed up with where KRBK is at 1 edge conditions according to the simulator. Are you not thinking that the peak of the 2nd story would be better for KRBK?

You are welcome! Glad we were able to make a big improvement in your reception without causing harm to you or your equipment. And, you are getting your money's worth from your AC7 because it is now doing what it is supposed to do.

The computer simulation is not that precise. The results that you are getting in signal strength, errors, and picture quality is what counts.

What does your tvfool report look like with the new coordinates? I think I only have the one you gave in post #2, or did I miss it?

The ones I gave ADTech are really about the same. I just wish I could figure out why I am getting the error messages on ABC-KSPR channels. It is my strongest signal. I guess we have concluded the 10-1 is due to VHF being more susceptible to interference...

The signal might be too "hot" for the Roamio tuner. A simple test would be to insert a 2-way splitter between the C2V and the input of the AC7, which would attenuate the signals 3.5 dB; two splitters in series or a 4-way splitter would attenuate the signals 7 dB.

If you want some actual fixed attenuators:
http://www.mjsales.net/itemsearch.asp?FamilyID=221

They also have power passing attenuators, but you don't need that kind now.

Yes, electrical interference is greater on VHF. It could also be from multipath reflections coming from other directions because of the simple Vhf antenna. Again from ATSC A/74:

http://forum.tvfool.com/attachment.p...1&d=1415329859

A more directional VHF antenna would reject many of those reflections.

Note from the table that the greater the difference in time between the main signal and the echo (reflection), the weaker the echo must be to not interfere with reception.

How often do you see the uncorrected errors? Once-a-day for a few minutes, or more like almost constantly?

Do you see picture and audio problems on your TV only when you have errors?

My primary interest is in measuring signal strength and signal quality of DTV signals, so I wanted see what the Roamio Diagnostics Screen looked like.

I downloaded the Roamio user manual, but I didn't seen any screen shots:
http://assets.tivo.com/assets/resour..._19AUG2013.pdf

I then did a Google search:
https://www.google.com/?gws_rd=ssl#q=TiVo+Roamio+SNR

This is for cable, but I think OTA is similar
Troubleshooting Digital Cable Signals (BOLT, Roamio, Premiere, Series3)

Checking signal lock and signal strength

1. Navigate to the Signal Strength-Cable screen:

From TiVo Central > Settings & Messages > Settings > Channels > Signal Strength-Cable

2. Press Select to display the Signal Strength Meter. A warning screen appears, telling you that using the Signal Strength Meter will stop all recordings.

3. Select OK, access this setting. The signals strength meter appears.

Checking the signal quality

1. Tune to a channel that is having a problem.

2. Write down the channel number and then press RECORD to lock the tuner to the channel (Series3 only: If two CableCARDs are installed, this also locks the tuner to the CableCARD).

3. Navigate to the DVR Diagnostics screen:

From TiVo Central > Settings & Messages > Account & System Info > DVR Diagnostics

4. Under Tuner 0, look at the channel number. If the channel listed is not the problem channel, press Chan Down until you see the information for Tuner 1 (if you have a 4- or 6-tuner TiVo DVR, you might need to continue scrolling until you reach the correct tuner for the problem channel).

and found this document from TiVo: (link no longer available, do Google search)
Troubleshooting Digital Cable Signals: Roamio Series, Premiere Series, and Series3 DVRs
http://support.tivo.com/app/answers/detail/a_id/150

It had some images for the Diagnostics Screen. I copied the one for the errors, and edited it to make it a little lighter because the original was too dark:

http://forum.tvfool.com/attachment.p...1&d=1415328067

RS is short for Reed–Solomon:
https://www.google.com/?gws_rd=ssl#q=RS+errors
http://en.wikipedia.org/wiki/Reed%E2...ror_correction

If I put the 2 way splitter on the C2V before the AC7 combiner, would I just "cap" the extra out?

I can't say that the errors are there every single time I check. I have been going into the DVR Diagnostics nightly to check. I just noticed tonight the RS Uncorrected is up around 80 or so on 33-1. It isn't a completely unwatchable picture or non-stop picture problem when the errors are there. The best I could describe it is as a lined pixelation cut out that appears on the screen that is quite annoying.

I guess if the splitter doesn't work the only option I would have left would be to replace it with some sort of directional antenna?

Yes that is what the diagnostic screen looks like. I received a Wineguard HDA 200 amp in the mail today but I am assuming it wouldn't help anything although the amplification is supposed to be controllable via a nob or something. But, it may be "noiser" than the Winegard LNA 100. What do you guys think?

The HDA200 quite a bit noisier than an LNA100. You shouldn't have any need for it.

Any adventage or disadvantage to using a splitter vs. an attenuator? I'm assuming the 3db attenuator would be the one to get if going that route...

We really don't know what is causing the errors on 33.1. If it is from multipath reflections, then a more directional antenna might help. If the errors are caused by some other reason, like an unknown characteristic of the tuner, it wouldn't help.

When you started, most of the things you tried had a high chance of improving your signals. You are now at the point where they might not, and you must be willing to take that chance of failure. That's why I want you to try the simple things first.

The purists say that you should cap the unused port with a 75 ohm termination cap; practical experience says it doesn't seem to make much difference. Try it both ways to satisfy your own curiosity.
Not that I'm aware of except price and availability, assuming a good quality splitter.
This is an experiment. You don't yet know how much attenuation would make a difference, if any. Think of it as an adventure, not a chore.

When you mentioned attenuators, I realized I had 3 of these lying around: http://www.3starinc.com/fam-3_db_in_...uator_pad.html

So, I went up and connected one to the C2V antenna and then connected that attenuator into the all channel input of the AC7 combiner. I then rescanned for channels on the Roamio. Some 8 dash channels I was getting dropped off (they may have been analog stations i am not sure). I then proceeded to go into the DVR Diagnostic menu of the Roamio and checked all channels I was receiving. First off, 33-1 changed from about 80 on the RS Uncorrected amount to 0. Another interesting change is that 49-1 and 49-2 shot up to 67% signal strength (up from 62%) and the SNR went up to 27 dB on those channels. All other channels reported before remained at the constant on both signal strength and SNR from what i reported in post 21. Channel 10-1 also had 0 for RS Uncorrected but it was that way earlier this evening before adding in the attenuator.

What do you guys think about that? Why the jump on 49-1 and 49-2? The jumps wouldn't have anything to do with losing the 8 dash channels would it?

I am going to check again tomorrow evening when i am home from work and see what the levels are reporting then.

Thank you for the report. That sounds like an improvement to me. Time will tell if it is a permanent improvement.

There is a story, that has many versions, about Thomas Edison when he was inventing the light bulb. He told a guest at his lab that he had, so far, done 1,000 experiments but had not yet perfected the light bulb. His guest asked, "How did it feel to fail 1,000 times?" Edison replied, "They weren't failures. I found 1,000 ways that didn't work, so I can now exclude them from consideration."

Take a look at this Google search for roamio signals "too hot":

https://www.google.com/?gws_rd=ssl#q...+%22too+hot%22

Looks like I may have spoken too soon. I couldn't resist checking the levels this morning before I left for work. 49-1 and 49-2 were down to 52% (22 SNR) on the signal strength menu (from the 67% after I first inserted the 3 dB attenuator). I didn't expect to see that all (there were also a small amount of RS Uncorrected errors present on those two channels). Not sure if that was due to the attenuator or something else.

33-1, 33-2, and 33-3 had dropped a little in signal strength too but no signal errors.

I"m not sure what happened...

Not a surprise. OTA signals constantly vary in strength, especially 1Edge and 2Edge signals.
It couldn't be from the attenuator because it was in the coax line from the other antenna.

Raising the 91XG as ADTech suggested might make 49 stronger.

KTKO-LP digital and KTKO-LP analog are both very weak. No surprise there either, because of their very negative NM numbers, based on your old report:
http://www.tvfool.com/?option=com_wr...d24362e8886d03

Good; that's what the attenuator was supposed to do.

How is 10.1 doing now?

10.1 continues to get sporadic RS Uncorrected Errors as well as 33-1 and 49-1. Nothing else seems to do that.

Oddly enough even with the attenuator, 33-1, 33-2, and 33-3 continue to be around 67% signal strength (which is what they are at after inserting the LNA 100 and before putting the 3 dB attenuator in the mix).

I don't mind losing the KRFT channels as there is nothing on there I watch anyway.

Do you have any other ideas I should try?

Thanks for the report.

While the fix helped for a while, it looks like it was not permanent. Since the errors increased when the signals were stronger, this suggests to me that you should try increasing the attenuation between the C2V and the input of the AC7.

I think you said that you had 3 of the 3 dB attenuators. So, try 6 dB (they stack in series don't they?) for a few days, and then increase it to 9 dB before giving up on this idea. This should not affect the reception with the 91XG.

If you add the whole stack of attenuators to the input jack of the AC7 it might put too much strain on it. You can insert them in the middle of the coax with a short jumper coax and an F81.

Have you tried tilting the 91XG up a little to see if it improves the reception of Fox?

I'll stick around with you until I run out of longshot ideas to try, or until you give up and settle for what you have now.

Are the coax lines from the antennas grounded with grounding blocks that are connected to your electrical system ground? I'm thinking about interference with this question. It's also a good idea for electrical safety.

Do all your pieces of AC operated equipment have 2-wire power cords, or do some have 3-wire cords?

Are you using power strips that have provision for coax grounding? If so, are you using that feature? It's not always a good idea to do that.

The power strip will ground the coax shield if it is connected to a properly wired 3-wire outlet. But, the coax center conductor might pickup electrical interference from the other devices plugged into the strip, and the TV signal might be degraded if there is a surge protector connected between the center conductor of the coax and the shield.

What make and model TV is directly connected to the Roamio output? Does it have a signal strength indicator or a Diagnostics Screen? Are you using an HDMI cable, or what between them?

http://forum.tvfool.com/attachment.p...1&d=1415676008

Virtual 33.1 KSPR-DT, real channel 19, is your strongest station, but its virtual number is not shown on your tvfool report:
http://www.tvfool.com/?option=com_wr...d24362e8886d03

I put two of the 3dB attenuators back to back connected to the C2V coax, an F81 connector, then a short piece of coax to the AC7. Oddly, it seemed to not really affect the signal strength of KSPR.

I know you asked about the virtual number of KSPR. ABC is 33-1, CW is 33.2, and Antenna TV is 33-3.

I don't know about the grounding blocks.

Your question about the AC operated equipment having 2 wire power cords or 3 wire cords I need some clarification on because I'm not sure what you are asking.

Are you using power strips that have provision for coax grounding? If so, are you using that feature? It's not always a good idea to do that. Yes I have this surge protector in use in the attic (but am unsure about any coax grounding provision): http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

Here is a link to the model of the TV I have connected to the Roamio: http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

I know the TV has a signal strength indicator. I'm not sure about a Diagnostic screen. I'm sure all of my TV's tuners are "better" than any of the DVR's I have on hand (Tivo Roamio and a Channel Master DVR+, which is not in use). It seems all TV's seem to be that way...

I'm also sending you a Pm with the same coordinates I sent ADTech so you can get a better idea of location, obstacles, etc. I am also going to send you a second set of coordinates for something that I am wondering if it could be causing me interference.

I've asked this a couple of times but haven't gotten any responses so I'll ask again. If I moved the 91XG to the peak of the 2nd story of my home, what equipment would I need for mounting it there. I'm hoping you may be able to answer after looking at the coordinates I gave you.

Are you asking about the mechanical process of mounting an antenna on the roof peak?

If so, you'll need some sort of mast and a way to support it. This could be a gable end bracket, a tripod, a chimney mount, or a ridge bracket with guy wires. Mostly it depends on your roof configuration and which method most appeals to you.

Look here for some ideas about mounting brackets - http://www.antennapartsoutlet.com/ - I've bought from them. The shipped fast and had reasonable shipping charges.

You can also use a satellite-style J-mount, but you're be restricted to a length of about a meter or so.

Good to know. I was wondering if you would be willing to check out these coordinates I sent rabbit and see if this might be causing the signal errors I continue to see.

The coordinates are 37.025154, -93.205803

Don't know. That location doesn't appear when I do a tower search in the area. Assuming it belongs to one of the local fire protection districts, it will be operating in either the 150-155 MHz or the 450-455 MHz bands.

The only way you'd be able to positively correlate your intermittent decoding errors with some local RF transmission would be to sit there with a spectrum analyzer watching it and your diagnostic screen (or display) and see if you can spot some sort of broadcast that occurs at precisely the same time as a decoding error. It would be like looking for a needle in a haystack unless you could narrow down any of the variables.

Well I see. I'm still looking for any kind of patterns with the errors, but I guess unless rabbit has other ideas that only leaves changing out the C2V to something more directional and see if that resolves these signal errors. Is that fair to say (since two 3dB attenuators have been added and the signal errors still occur)?

If it is, what would be some reasonable alternatives to consider? I really like the form and aesthetics factor of the C2V especially when coupled with the more directional 91XG and hate the idea of replacing it but the cutouts on 33-1, its subchannels, and 10-1 are driving me nuts. The only other channel that on a more rare occurance that has the occasional error is 49-1 Fox. Everything else always sits at 0 since switching to yours and rabbits suggestions.

The reason I have been inquiring more about how to mount the 91XG on the peak of the roof as you mentioned is because of the possibility of needing another directional to eliminate the errors on 33-1, its subchannels, and 10-1 while maintaining error free on the other channels. I thought it might be difficult to place two directional antennas where the two in use are located (not to mention being a bit of an eye sore).

Don't give up yet, I still have some more ideas for you to try.

You are not the only Roamio owner that has a love/hate relationship with his DVR:
Tivo Roamio Plus can be great, but check it out carefully before keeping it longer than 30 days
http://www.avsforum.com/forum/42-hdt...n-30-days.html

Thanks for the exact coordinates. I ran your FM fool report to see if there were any strong FM signals that might be causing interference. With FM fool there is no link like there is for tvfool reports. I deleted the numbers after the decimal point to protect you, even though the report only shows two digits after the decimal point. I also ran some tvfool reports at different heights, but I will not post them unless you give me permission to do it. They also have truncated coordinates, so the approx. coordinates are pretty far away from your exact location. This is your FM signal report:

http://forum.tvfool.com/attachment.p...1&d=1415926465

When you make a reply to one of my posts, it is not necessary to quote the entire post. You can delete the parts of the quote that are not needed, or you can copy and paste what I said, highlight it and click on the quote icon at the top of the text box above the red A, which will add the quote box to your post.

http://forum.tvfool.com/attachment.p...1&d=1415927509

I agree with ADTech.

No, it is not fair to say that. If you look at your original tvfool report you will see that the signals received by the C2V are very strong, with large Noise Margins. This means that you can add a LOT more attenuation before the signals become too weak for the tuners.
http://www.tvfool.com/?option=com_wr...d24362e8886d03

If I were there with you, I would want to add much more attenuation to see if the errors were gone while still having enough signal strength for the tuner. The reason I feel that way is because of the many comments by other Roamio users about it not being able to handle strong signals.

Take another look at this Google search for roamio signals "too hot":
https://www.google.com/?gws_rd=ssl#q...+%22too+hot%22
http://www.epinions.com/review/TiVo_...587068548?sb=1

A DVR that can record more than one channel at a time must have more than one tuner. As ADTech said, there must be a splitter in the DVR to send the signals to multiple tuners. He and I both think that the DVR uses a zero gain splitter, which is a splitter with an amp that adds just enough gain to make up for the splitter losses.

You have already discovered that the TiVo values for SNR are not realistic because they are determined for cable use, not OTA use. It is my opinion that there is a similar problem with the acceptable levels of signal strength for the Roamio. The tuners are probably similar to the tuners in a TV, but the zero gain splitter was designed for cable signals that have a much more narrow range of strength than OTA signals. The engineer who designed the splitter was designing it for cable signals, not OTA signals, which could mean that it was never meant to handle such strong OTA signals.

There are two tests that you can do to see if my theory has any merit.

The first test would be to get several each of 10 dB and 20 dB inline attenuators to add to your attenuator collection. Add more attenuation between the C2V and the AC7 and see what happens to the errors; never mind about the signal strength as long as there is enough left for the tuner to decode the signals for proper reception. You have plenty of NM available before you get down to 0 NM. And you have plenty of dBm Pwr before you get down to -83 dBm, which is where you will reach the "digital cliff."

Earlier you said:
I can understand how that might be difficult. Your basement TV is a 60-incher; it is a lot of work to move a large TV. That TV is a Panasonic VIERA TC-P60ST60, which is a nice TV with good reviews.

What I want you to do as a second test is to disconnect the antenna coax from the Roamio and connect it to the P60ST60 to see how it behaves with the same signals that were going to the Roamio. The results might give us a clue about what improvements can be made to your antenna system.

When I have more time, I will give you some more answers.

It is okay to post the other tvfool reports if you think they will help. Let's just not try to reveal my exact location for the whole web to see.

So I need clarification here. Are you saying to use enough attenuators to account for 10 or 20dB total? If you are suggesting something else can you link to where I bought from before what I would need?

I have one more 3dB attenuator left that if I would add to what is already in use would total 9dB. So far, the only channel's signal strength affected is 33-1, 33-2, and 33-3.

[QUOTE=rabbit73;47796

Earlier you said:
I can understand how that might be difficult. Your basement TV is a 60-incher; it is a lot of work to move a large TV. That TV is a Panasonic VIERA TC-P60ST60, which is a nice TV with good reviews.

What I want you to do as a second test is to disconnect the antenna coax from the Roamio and connect it to the P60ST60 to see how it behaves with the same signals that were going to the Roamio. The results might give us a clue about what improvements can be made to your antenna system.

When I have more time, I will give you some more answers.[/QUOTE]

How should I do the comparison? When switching back to the Roamio go back into the Diagnostics menu to check Uncorrected Errors?

The quote didn't work because you left out the ] after the 47796.

There is no point in switching back and forth, because the signals would have changed by then, which is why I had suggested the two-set comparison which gives you a real-time comparison.

What I'm suggesting now is a second-best test because it would be difficult for you to bring a second set down to the basement, unless you have or can borrow a smaller set.

You already know what the Roamio does with the present antenna system. I want you to see what a TV does with the present antenna system.

I'm saying keep adding more, a little at a time, and see what happens, until there is no signal left. This is the test in the link in my signature.
I got mine here:
http://www.mjsales.net/items.asp?Fam...266&Cat2ID=125

You got yours here:
http://www.3starinc.com/fam-3_db_in_...uator_pad.html

They already know it's Ozark, MO from your original tvfool report, and you gave the coordinates of the nearby firehouse in an open forum. I'll be extra careful. I'll just do an extract from the other reports.

So how many 10dB and 20dB in line attenuators do I need to pick up? I'll add my last 3dB attenuator to the C2V while I wait.

i asked what I did about the TV comparisons because I was unsure how to compare since I can have error messages showing in the Diagnostics Menu on the Roamio yet it doesn't cause non-stop picture problems. It can even be a sparse picture problem yet quite annoying.

Just try different increasing values and see what happens. This is an experiment; we don't know how it will turn out. I can't afford the plane fare to come out there, so we are counting on you to do the experiments.

There should be no harm in adding more attenuation to the point of dropout. The screen will say no signal, which is what it would say if you removed the antenna coax.

You should have enough attenuators to equal the NM of your strongest signal ~ 65 dB. That would be two 10 dB, two 20 dB, and the three 3 dB that you already have.

I have to leave. I need to eat because my blood sugar is low, which makes me cranky as a two-year-old who needs a nap.

I ordered two 10db, two 20db, and single 6, 12, and 16 dB attenuators that should get here by the Tuesday or Wednesday of next week.

So, I guess what I will do is continue adding attenuators until I lose all channels but Fox. As I add, I will record what I am getting in the DVR diagnostic menu along the way. I will post each recording here. I took a 6dB attenuator reading last night that I will post today and when I get home this evening I will post the 9dB readings (since I added my last on hand attenuator this morning).

Here are the 6dB Attenuator results:

Channel 3-1 25 dB SNR, 62% signal strength, RS Corrected 0, Rs Uncorrected 0

Channel 3-2 Same as 3-1

Channel 3-3 Same as 3-1 and 3-2

Channel 10-1 29 dB SNR, 72% signal strength, RS Corrected 0, RS Uncorrected 18

Channel 21-1 29dB SNR, 72% signal strength, RS Corrected 0, RS Uncorrected 0

Channel 21-2 Same as 21-1

Channel 21-3 Same as 21-1 and 21-2

Channel 27-1 29dB SNR, 72% signal strength, RS Corrected 0, RS Uncorrected 0

Channel 33-1 25dB SNR, 62% signal strength, RS Corrected 0, RS Uncorrected 90

Channel 33-2 25dB SNR, 62% signal strength, RS Corrected 0, RS Uncorrected 84

Channel 33-3 25dB SNR, 62% signal strength, RS Corrected 0, RS Uncorrected 202

Channel 49-1 25dB SNR, 62% signal strength, RS Corrected 0, RS Uncorrected 0

Channel 49-2 Same as 49-1

Diagnostic readings were taken around 11:30 p.m. on 11-14

Not to compare apples to oranges, but I remembered my Channel Master DVR+ had a signal quality diagnostic so I connected to it on the same TV and got 100% signal quality even on the stations that I got errors on from the Tivo diagnostic. Kind of interesting.

Thank you for the 6 dB attenuator test with the Roamio DVR. Please try more attenuation when it is available. Start with 10, then 20, then 30, then 40, and then 50 dB.
Yes, very interesting. What does that tell you? Are you able to make any conclusions based on the CM DVR+ test?

Now, please connect the antenna to the Panasonic TV and tell us about the reception quality as a viewer; never mind about errors. If there were uncorrected errors in the Panasonic, it would affect the reception quality.

I now want to talk about grounding. There are three areas that overlap concerning grounding:

1. The NEC requires outdoor antennas to be grounded.
2. Grounding affects the performance of your equipment.
3. Grounding protects you from shock.

NEC REQUIREMENTS

The NEC requires the antenna coax (two in your case) to be grounded using a grounding block, which they call an ADU, Antenna Discharge Unit.
http://www.solidsignal.com/pview.asp...grounding-lugs

The grounding block should be connected to the house electrical system ground with 10 gauge copper wire.
The antenna mast should also be grounded with another 10 gauge copper wire connected to the house electrical system ground.
This is to drain any static buildup which, in theory, would reduce the chances of a direct lightning strike, and protect you from electrical shock. See attachments 1 and 2.

See these threads:
General Technical & Safety Information
http://forum.tvfool.com/showthread.php?t=901

Grounding Antenna and Dish
http://www.avsforum.com/forum/25-hdt...enna-dish.html

EQUIPMENT PERFORMANCE

Equipment that has a 2 wire power cord is not grounded by the cord; equipment that has a 3 wire power is grounded by that cord. If a piece of equipment with a 2 wire power cord is connected by a wire with a grounding shield to a piece of equipment with a 3 wire power cord, then the equipment with the 2 wire power cord is indirectly grounded.

Equipment like a tuner, a TV or an AC7 is expected to be grounded when in use to protect it from RF interference.
Your power strip does not have that provision.
http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

But this one does:
http://www.amazon.com/Tripp-Lite-TLP...SR8VY9F6CDQD8J
You can see the two coax connectors at the center of the strip. Using those connectors for your antenna coax might expose it to interference from the other equipment connected to the strip and there might be internal surge protection between the center conductor of the coax and the shield that can degrade the signal.

ELECTRICAL SAFETY

When I was calibrating an Apex DT502 converter box for a friend, I received a mild shock when I touched the equipment and the metal strip on the front edge of the counter. The strip was grounded because it touched the metal stove top.

http://forum.tvfool.com/attachment.p...1&d=1416019951

All AC operated equipment has leakage current. Just because you can't feel it doesn't mean that it isn't there. All these pieces of equipment were connected together by a 4-way splitter, and were operating normally in that their individual leakage currents were within safe limits. But, since they were connected together their leakage currents added together, and that's why I felt a mild shock. The setup was using a temporary outside antenna that was not grounded. When I grounded the splitter, the leakage current went to zero.

Having three close calls with electrical shock, I consider the grounding block essential in any antenna system.

Voltage/shock issue
http://www.avsforum.com/forum/25-hdt...ock-issue.html
Getting A/C voltage on converter box's antenna input !
http://www.digitalhome.ca/forum/show...postcount=1022
Equipment Leakage Current
http://www.digitalhome.ca/forum/show...postcount=1025
Proper grounding can protect you from leakage current shocks
http://www.digitalhome.ca/forum/show...postcount=1099

I know you said a 10 dB results but I already had the 9dB results before that.

Here they are:

Channel 3-1 24dB SNR, 60% signal strength, RS Corrected 0, RS Uncorrected 0

Channel 3-2 24 dB SNR, 60% signal strength, RS Corrected 0, RS Uncorrected 18

Channel 3-3 24 dB SNR, 60% signal strength, RS Corrected 0, RS Uncorrected 12

Channel 10-1 29dB SNR, 72% signal strength, RS Corrected 0, RS Uncorrected 87

Channel 21-1 29dB SNR, 72% signal strength, RS Corrected 0, RS Uncorrected 0

Channel 21-2 Same as 21-1

Channel 21-3 Same as 21-1 and 21-2

Channel 27-1 29dB SNR, 72% signal strength, RS Corrected 0, RS Uncorrected 0

Channel 33-1 27dB SNR, 67% signal strength, RS Corrected 0, RS Uncorrected 12

Channel 33-2 27dB SNR, 67% signal strength, RS Corrected 0, RS Uncorrected 84

Channel 33-3 25dB SNR, 62% signal strength, RS Corrected 0, RS Uncorrected 222

Channel 49-1 25dB SNR, 62% signal strength, RS Corrected 0, RS Uncorrected 0

Channel 49-2 Same as 49-1

Also saw on tivocommunity.com that RS is Reed Solomon. Digital transmission systems incorporate a scheme called Forward Error Correction which uses Reed Solomon error correction codes

RS Corrected indicates that the demodulator detected a block with an error in it and the RS code was able to correct the error. RS Uncorrected means the error was beyond the capability of the RS code to correct. An uncorrected block most likely will result in a pixelation or a dropout event.