HDHomeRun Prime Tuner Signal Quality

[KeithAbbott]

I've been trying to do some optimization of my Primes, and ran into something curious. I have two Primes, with a total of six tuners. I have an inline coax attenuator on the input to each Prime, so that the signal strength reported by the Primes stays between -6.0 and -0.6 dBmV (90 to 99 percent). Overnight, I ran a script that tuned all six tuners to one of my most frequently watched channels for 10 minutes, paused for 15 seconds, then tuned another frequently watched channel on all six tuners. This was repeated a total of 13 times, for each of my most frequently watched channels. For the two-plus hours that the script ran, the signal strength stayed between -5.0 and -1.1 dBmV.

The signal quality, for those two-plus hours, stayed at 100%. The exception was one of the six tuners; 10 of the channels recorded on that tuner had signal quality of 100%, while the other three channels had between 65% and 93% signal quality. Mind you, the other two tuners for that device, tuned to the exact same channel during the exact same ten minutes, had 100% signal quality. The signal strength for the tuner in question during that time period ranged between -2.4 and -1.8 dBmV.

Is this expected behavior? Is there any explanation for what may have occurred? Is it possible that that one tuner may have overheated during the two-plus hour exercise? This does not seem like an issue on the cable providers end, since the other two tuners in that device had 100% signal quality for the same channels during the same time frames.

p.s. fyi, I track and record the signal strength and signal quality reported by the Prime every 60 seconds, if that makes a difference.

[signcarver]

Usually the first symptom of a power supply going bad is problems with one particular tuner or when multiple tuners are being used. Personally I prefer the primes signal strength to be a little positive as unlike the ota models you should see the dBmV (strength) value which can usually go as high as +10 without issue (+/-10, though some say 15, with 0 being "perfect" but I do prefer the hot side of +/-7) and since you can see that strength as a real number you do know how much above 100% it is with still being in spec, but your strength should be fine and don't over amplify any noise (don't use an amp to bring such up, but may wish to drop attenuator).

Different frequencies will have different qualities.

[jasonl]

If you're picking up interference from another device, the tuners that are physically closest would be affected more. Usually happens if someone stacks their HDHomeRun directly on a wireless router or something like that. Giving them a couple feet of separation can clear up this type of issue.

[KeithAbbott]

Usually the first symptom of a power supply going bad is problems with one particular tuner or when multiple tuners are being used. Personally I prefer the primes signal strength to be a little positive as unlike the ota models you should see the dBmV (strength) value which can usually go as high as +10 without issue (+/-10, though some say 15, with 0 being "perfect" but I do prefer the hot side of +/-7) and since you can see that strength as a real number you do know how much above 100% it is with still being in spec, but your strength should be fine and don't over amplify any noise (don't use an amp to bring such up, but may wish to drop attenuator).

Different frequencies will have different qualities.

I can't believe I didn't think about the power adapter, usually I'm the first one to bring that up. Anyhow, I swapped power adapters between the two Primes, but the same tuner is still showing <100% signal quality. And that was with the other five tuners inactive. So I'm thinking that rules out the power adapter.

As far as my signal strength, I'm basing that on a since-deleted post in this forum, nickk had provided the tuner manufacturer's specifications. I do use a zero gain/loss distribution amplifier (for my cable modem, Primes, and actual coax drops into two of the rooms in my house) along with an inline attenuator to knock the signal strength down. I can easily try removing the attenuator to see if that makes a signal quality difference. Replacing the distribution amplifier will take a bit more effort, since that also feeds my cable modem.

If you're picking up interference from another device, the tuners that are physically closest would be affected more. Usually happens if someone stacks their HDHomeRun directly on a wireless router or something like that. Giving them a couple feet of separation can clear up this type of issue.

I have my Primes in a 12U rack mounted on the basement wall next to where the cable feed comes into the house. My network rack (named to distinguish from my server rack, located on the opposite end of my basement) has my distribution amplifier, Arris cable modem (non-wifi), two Primes with associated Vecima HSC devices, a Trendnet 8-port gigabit switch, and a Tripp Lite UPS device. My router (also non-wifi) is located in the server rack on the other side of the basement. The tuner in question is located in the Prime that is sandwiched between the other Prime (above), and the gigabit switch (below). The UPS is under the gigabit switch.

I could pull the shelf containing the Prime and it's HSC out and re-try it from several feet away from the rest of the rack and see if that makes any difference. That would tell me if either the switch or the UPS is creating RF interference.

[KeithAbbott]

Usually the first symptom of a power supply going bad is problems with one particular tuner or when multiple tuners are being used. Personally I prefer the primes signal strength to be a little positive as unlike the ota models you should see the dBmV (strength) value which can usually go as high as +10 without issue (+/-10, though some say 15, with 0 being "perfect" but I do prefer the hot side of +/-7) and since you can see that strength as a real number you do know how much above 100% it is with still being in spec, but your strength should be fine and don't over amplify any noise (don't use an amp to bring such up, but may wish to drop attenuator).

Different frequencies will have different qualities.

I can't believe I didn't think about the power adapter, usually I'm the first one to bring that up. Anyhow, I swapped power adapters between the two Primes, but the same tuner is still showing <100% signal quality. And that was with the other five tuners inactive. So I'm thinking that rules out the power adapter.

As far as my signal strength, I'm basing that on a since-deleted post in this forum, nickk had provided the tuner manufacturer's specifications. I do use a zero gain/loss distribution amplifier (for my cable modem, Primes, and actual coax drops into two of the rooms in my house) along with an inline attenuator to knock the signal strength down. I can easily try removing the attenuator to see if that makes a signal quality difference. Replacing the distribution amplifier will take a bit more effort, since that also feeds my cable modem.

Quick update, I tried removing the attenuator, the signal quality still ranged from 73-75% for the tuner in question, the signal strength did increase to between +6.1 and +6.5dBmV. The other two tuners stayed at 100% signal quality for the same channel. I'm going to try removing the shelf with the Prime next, and testing it with a distance of several feet from the rack.

[KeithAbbott]

If you're picking up interference from another device, the tuners that are physically closest would be affected more. Usually happens if someone stacks their HDHomeRun directly on a wireless router or something like that. Giving them a couple feet of separation can clear up this type of issue.

I have my Primes in a 12U rack mounted on the basement wall next to where the cable feed comes into the house. My network rack (named to distinguish from my server rack, located on the opposite end of my basement) has my distribution amplifier, Arris cable modem (non-wifi), two Primes with associated Vecima HSC devices, a Trendnet 8-port gigabit switch, and a Tripp Lite UPS device. My router (also non-wifi) is located in the server rack on the other side of the basement. The tuner in question is located in the Prime that is sandwiched between the other Prime (above), and the gigabit switch (below). The UPS is under the gigabit switch.

I could pull the shelf containing the Prime and it's HSC out and re-try it from several feet away from the rest of the rack and see if that makes any difference. That would tell me if either the switch or the UPS is creating RF interference.

I pulled the shelf containing the Prime and it's HSC out, and ran my script for the channel that I seem to be having the most issues with. The shelf is now 2-3 feet away from the rack. I have the same results as before: all of the other tuners have a signal quality of 100%, the tuner in question has a signal quality of 71-74%. I'm starting to think that tuner is a little wonky. Which is strange, because it has signal quality of 100% on many/most of the other channels.

I'll try to figure out a time to bypass the distribution amplifier and see if that makes any difference. Since that will require an internet outage, I have to schedule it with my other family members in mind.

@jasonl, I have diagnostics turned on for both of my Primes, let me know if you want me to recreate the problem so that you can look at the logs. Not sure if that will give any insight or not.