That makes sense. Almost like audio amplifiers producing harmonics when clipped. Thanks for all the help guys. This is very interesting stuff but not for the faint of heart.

ADTech did some interesting tests that show how weak signals are damaged when a preamp is overloaded by strong signals:

Just the antenna, no preamp:

http://forum.tvfool.com/attachment.p...7&d=1441052886

This is what the same signals look like when the preamp is moderately overloaded. Notice that the weakest signals are damaged first. The noise floor rises from the spurious signals created by the IMD. This reduces the SNR of the weak signals to less than the required 15 dB minimum:

http://forum.tvfool.com/attachment.p...0&d=1441054170

This is what the same signals look like with a badly overloaded preamp:

http://forum.tvfool.com/attachment.p...8&d=1441052947

This is what the same signals look like with a high quality preamp that isn't easily overloaded:

http://forum.tvfool.com/attachment.p...9&d=1441053000

Yes, exactly. Clipping produces harmonic distortion products. Intermodulation distortion produces spurious signal products.

I think you are ready for it because of your desire to improve your reception.

Ok, removing the db8e from the equation gives me identical results. Any other ideas? Too much FM?

edit: ok it seems to be worse. Signal quality is around 45 now

Just ran a test by hooking up the antenna output to my stereo. I am still able to bring in local fm channels crystal clear even with the fm trap on in the preamp. Could this be causing the problem?

edit: also interestingly enough while trying to tune in to a detroit fm station I am getting spillover from one of the locals even though they are about 5 MHz apart (turning the trap back on stops this)

Sorry to keep adding stuff on here but I am unsure if this is pertinent information or not. It seems as the temperature outside gets warmer throughout the day the signal gets worse.

http://forum.tvfool.com/attachment.p...9&d=1441155005

Well, at least your getting Fox even if it's not a high quality signal.
That eliminates the strong UHF signals coming in from the DB8E. The C5 is still picking up UHF signals, but they will be attenuated by the low pass filter in the combiner by 25 to 40 dB before reaching the preamp.
That test is inconclusive. You are probably getting some attenuation from the FM filter in the preamp, but it's not going to completely eliminate FM signals. A good FM tuner doesn't need much signal to function.
That proves the filter is doing some attenuation. Your strongest FM signal is 65 dB stronger than Fox. I suspect that the preamp doesn't like that, and it is creating distortion products that reduce the SNR of Fox which gives you a low Signal Quality reading. You would need test equipment to see exactly what the numbers are, but you can still try a preamp that is more resistant to overload and some different filters.

All FM filters aren't alike; they have different attenuation curves and a HLSJ can also be used as an FM filter. It attenuates all signals below CH7, including the FM band. See attachments 2-4.

I'm wondering if you could go back to your original setup where you were using the preamp for both antennas but insert several filters before the preamp input. That might also be inconclusive if the strong signals were getting into the plastic case of the preamp which would bypass the filters.

Then you could try a preamp with a metal case that is resistant to overload in place of the preamp with the plastic case. You missed the boat on the Juice, but another one might do.

You could also try a preamp in a metal case that is resistant to overload with an FM filter in front of it to amplify just VHF, but you would need a UVSJ that passes DC to the preamp.

Is your coax grounded with a grounding block? That reduces interference and makes filters much more effective.

OTA signals constantly vary in strength, especially non-LOS signals, and are affected by temperature inversions.
Keep the ideas coming, one of them might click. It's too soon to give up.

Was this TL;DR?:)

Not TL;DR at all. I will order up some fm traps and see if that helps. Buying another amp right now is out of the question as i am running out of money lol. Are the Antennas Direct FM traps good for the job? Oh and i have a coax grounding block with a wire that runs to my plumbing, is that good?

They are good, but you have to look at the strongest FM signals to pick the best filter. The AD filter does a good job at the 88 MHz end of the FM band, but is a little lacking at the 108 MHz end. The Radio Shack filter does a good job at the 108 MHz end but doesn't attenuate well at the 88 MHz end to allow reception of TV channel 6. The MCM filter does well at both ends.
CJFIFM 99.9 MHz -14.4 dBm
CHKS-FM 106.3 MHz -22.1 dBm
CBEGFM 90.3 MHz -27.2 dBm
WSAQ 107.1 MHz -29.2 dBm

http://www.mcmelectronics.com/produc...800829%2Cd.eXY

Alright, I ordered 4 of the MCM ones. I guess i may as well work on some of the other stuff while i wait. Mainly grounding since I already have the guy wires installed.

Right now the wires come in the front of my house and are grounded to the water pipe there. Looking at the ground in my electrical panel it seems to hook up to my water line there ( I am sure this is not to code anymore but it may have been when the house was built)

Another option is i could run my coax to the back of the house and ground at the same spot the panel is. I have bought one of these: http://www.amazon.com/TII-Broadband-...tning+arrestor

Also for mast grounding can I run a wire to the same spot?

You have done the most important thing when you grounded the coax with a grounding block, to protect yourself from leakage current shock if any of the AC equipment that is connected to the coax becomes defective. The code also requires that the mast is grounded by a separate 10 gauge wire connected to the house electrical system ground.

http://forum.tvfool.com/attachment.p...3&d=1441206024

Probably OK

Right. But since my house ground system is connected to my water pipes I should theoretically be able to ground to any one of them? Or should it be close to my panel?

I'm not an electrician and I can't see your setup. The local electrical inspector has the final say, but you might not want to get him involved; some are more friendly than others. A local electrician could advise you. Todd Humphrey doesn't speak for the NFPA that publishes the NEC code, but he has some ideas that are helpful.
Satellite System Grounding
Part 2 - NEC Overview
Presented by Todd Humphrey
http://www.dbsinstall.com/diy/Grounding-2.asp

That device will ground a spike from the center conductor of the coax to ground. It is not required by the code but some people feel better when they have one. There is a similar device built-in some surge suppressor power strips that ground the coax. It has been known to degrade OTA signals and pick up electrical interference from the AC line in the same housing.

For the price of that device you could have bought an RCA TVPRAMP1R preamp. The RCA TVPRAMP1R preamp does have a history of quality control problems, but you can buy three of them for the price of one Channel Master 7778. One of the problems is with the separate/combined switch. If you have the switch in the separate position to use two antennas, one for VHF and one for UHF as in your case, sometimes the switch doesn't make good contact with the VHF antenna. The workaround is to use a UVSJ to combine the two antennas and connect the UVSJ to the combined input of the preamp.

I'll think about a way for you to use what you have now.

Haha yeah i know. Trust me you do not want to know what I paid for the amp i bought. Sometimes it sucks when you want to get things done right away.

edit: Would this work for all my connections to keep them weatherproof? http://www.homedepot.ca/product/liqu...des-bru/411161

Been there; done that.

It looks like it would work, but I don't have any experience with it.

http://static.dxengineering.com/pdf/...ax-TechTip.pdf

https://www.youtube.com/watch?v=6eHgyxo3e9A

http://www.qsl.net/n9zia/con_seal.html

http://forums.radioreference.com/ama...t-weather.html

Try this with your preamp if you want to amplify VHF and UHF, using the combiner that came with the C5:

If the preamp is still overloading even with the FM trap, insert an attenuator between the FM trap and the input of the preamp:

The idea is to find the value of attenuation that will provide enough gain for the weak signals without overloading the preamp with the strong signals. For this test the control on the inside power unit should be set for max gain, because you want the attenuation to be before the preamp.

You can use a combination of an adjustable attenuator and fixed attenuators for the test, then replace with a fixed attenuator/attenuators.

variable attenuator:
https://www.antennasdirect.com/store...ttenuator.html

fixed attenuators:
http://www.3starinc.com/drop_in-line_attenuator.html
http://home-automation.smarthome.com...=&w=attenuator
http://mjsales.net/collections/atten...ant=1083705673
Attenuation values 1, 3, 6, 8, 10, 12, 16, 20dB (FAM)
click on 1 dB for other values; the up and down arrows are faint

Alright thanks. I will let you know how it goes when i get the FM traps. I got a few just in case one wouldnt cut it.

So right after a thunderstorm i get 85% quality. Wtf

On WJBK? That's a clue for power line noise, which is common on VHF.
I answered:
It was power line noise.

Well it hasnt been very dry here lately. Over 90% humidity every day. If anything the humidity has dropped since it rained. If that is the culprit how would I go about fixing it?

edit: something like this perhaps? http://www.amazon.ca/CyberPower-CP85.../dp/B00429N18S

By finding the source like MikeBear did. Rather than repeating everything, please read his thread.
http://forum.tvfool.com/showthread.php?t=15701

It might be your problem, or not. Make some tests with AM receivers for the broadcast band and for VHF if you have a receiver that covers the aircraft band.

The best I have is a clock radio. Does it matter what frequency its set to in the AM band?

I use a battery operated portable radio that covers the broadcast band, 540 to 1610 kHz. Tune to the low end of the band where there are no stations, then try the high end. The ferrite stick antenna in the portable radio has a directional effect.

I have a VHF-Hi channel that is marginal. I can receive it sometimes when the SNR is 15-16 dB. When the noise level is higher, I can't receive it because the SNR is less than 15 dB. I am able to measure the signal and the noise in an adjacent unused channel, and my Sony TV gives me the SNR in the Diagnostics Screen. My old SLM (signal level meter) has an AM detector for the audio so I can hear the signal and the noise. It's the meter on the left; the newer meter on the right can also measure noise and signal.

http://forum.tvfool.com/attachment.p...1&d=1439220373

A car radio also covers the broadcast band. When I drive around town with the radio tuned to a frequency where there are no stations, I can hear the noise get louder when I get near power lines, especially the big high tension lines. This test doesn't work with the FM band on the radio, because FM is designed to reject noise.

The broadcast band is much lower in frequency than the VHF aircraft band (118-137 MHz) or the VHF TV band but often if you hear the noise on the broadcast band it is also on VHF TV frequencies. It is worse on VHF-Low than VHF-High.

http://www.arrl.org/files/file/Technology/HANDSON.pdf

Ok so interestingly enough it is my pc causing emi. shut it off and the signal goes from 50-50 to 65-70. Only problem is i am not sure what component it would be.

Thanks for the report. I think you have found the source, but there could be other sources. The component that usually causes the interference is the power supply. The power supplies now being used are called switch mode power supplies (SMPS), or "switchers" for short. They are more efficient than the older linear power supplies but have a tendency to produce a lot of EMI unless they have the proper filters installed.

https://en.wikipedia.org/wiki/Switch...e_power_supply

If your PC is a desktop, the power supply is inside. If you have a laptop, the AC adapter is the usual source and it is sometimes possible to buy an adapter that is less noisy like MikeBear did.

Some people modify the power supply in their computer and install extra filters, but that is beyond the ability of most users.

http://ka7oei.blogspot.com/2012/12/r...racket-rf.html
http://ka7oei.blogspot.com/2014/08/c...ing-power.html

I don't know of a source of low noise power supplies for a desktop, but this one claims "Premium EMI/RFI power filtration provides low noise and ripple for stable power delivery."
http://www.newegg.com/Product/Produc...w&gclsrc=aw.ds

EMI can be radiated through the air to your antenna or conducted through the power line, or both.

If the interference is radiated through the air the cure is to increase the distance between the source and the antenna.

If the noise is conducted through the power line, sometimes using a different circuit helps. An AC line filter can be installed near the source, and one can be installed near AC operated equipment that is being affected.

http://www.repairfaq.org/REPAIR/F_CompRFI.html
from the ham radio viewpoint

Thank you for the info. I built the computer so i am familiar with the power supply (desktop). Its was not a cheap one so i am suprised that it would be causing so much emi. As for other sources of interference in the house i can pretty much rule thise out as i shut off every other breaker except the one the amplifier and hdhomerun are on. The computer and the amplifier are on seperate circuits already and the computer is about as far away from the antenna as i can make it. Short of putting it in the basement.

Edit: putting the side of the computer case on did seem to improve things a bit. So it is probably radiated through the air. Can the amplifier itself pick this up? They are in adjacent rooms.

what amplifier?

The antenna amplifier. Preamp i suppose its called.

Ah, yes the Antennacraft 10G212. That has a plastic case doesn't it?

Yes it does

Preamps with a plastic case don't reject EMI as well as preamps with a metal case according to ADTech, and yours has two plastic case units. It does help that your coax is grounded.

Did you try the FM filter yet? We are now on page four and I'm having a hard time keeping track.

Not yet. I am still waiting for the shipment. I do have some metal foil tape i could put on the case of the unit, if that would help.

That might be an interesting experiment with aluminum foil, but don't leave it on too long because of heat buildup.

It could be getting into your HDHR. Can you try a test with antenna into a TV tuner, eliminating the HDHR?

I did that into my panasonic tv. Pretty much the same

Was the computer off or on then during the antenna directly to Panasonic without HDHR test?

You need your computer when you use the HDHR don't you?

Well this is a different computer. So it isnt needed for the HDHR. And the computer was on when i tried the tv directly.

If that computer is in use while someone is watching TV, then you will need to find a way to reduce the EMI that it is creating. Maybe one of these ways:

1. AC line filter for computer
2. Power supply with better filtering for low EMI
3. Better shielding for computer case
4. Is the monitor creating EMI?

Does the computer have a 3-wire power cord that has the grounding pin connected to a properly wired 3-wire AC receptacle?

So i got my FM traps and they did not help the situation out at all. I even put three of them inline with no appreciable change. It looks like we have narrowed this down to the emi interference. I am going to have to do a few more tests. I am going to put foil on the window of my case and see if that improves it. I will also see if it is the monitor. Failing all that i will have to spend some money on line conditioners. If that doesnt work i guess i will have to shut down the computer while i am watching fox.

I'm wondering if a low EMI power supply for the computer, or an AC RFI line filter for the computer would help.

How about a Faraday Cage for the computer?

Just kidding, that would be an extreme solution.

I will build a faraday cage if need be.... assuming my wife lets me. I was looking into emi/rf interference mitigations and i came across this
Cleansweep 10A

While i think something like this may work i cannot find any prices on them. Another option could be one of these:
ISOBAR6 Ultra