# 921 internal HD tuner problems



## RocketNJ (Jul 29, 2003)

Hi All,

I've had my 921 a month now but haven't had much time to use it due to travelling. 

I've recorded a bunch of OTA HD shows and found I suffer from the "multipath" problem. I use quotes since I feel this is not just related to multipath but rather a defective OTA ATSC tuner in the 921.

I've got a Winegard HD-9085P antenna on my chimney about 25 ft off the ground. I'm using a Winegard AP4800 mast mount preamp and the system is fed with RG-6U cable. The antenna cable is grounded where it enters the house using a PolyPhaser lightning protector designed to pass the D.C. voltage for the preamp.

When using the 921 tuner I get pixelation and loss of signal on channels 2-1, 5-1, and 11-1 (off of Empire State Building in NYC). The signal on those channels vaires around 10 to 15 units in signal strength. The lowest the signal drops is around 96. Most are around 120 to 125 signal at peak.

Channels 4-1, 7-1, and 38-1 are all between 120 and 125 signal and do not have the varying signal. They are transmitting off Empire State also.

My Panasonic PT-60LCX63 tv has a built in ATSC tuner and I can receive ALL the channels mentioned above with no pixellation or dropouts. Signal ranges around 75 to 95 (on a scale to 100). No "multipath" problems noticed on the Panasonic's tuner.

I've tried tweaking the direction of the antenna and reduced the problem but have not eliminated it. I've also tried bypassing the preamp at the top and bottom. Any ideas? Since the tv's ATSC tuner works fine it sure looks like the 921's tuner is either bad or of poor quality.

Thanks,
Dave


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## Mark Lamutt (Mar 24, 2002)

The first thing I'd try, Dave, is taking the preamp completely out of the equation. I would then delete all of the channels from the channel list, reboot the 921 and then scan your channels back in. If that doesn't solve the problem, there are some other things to do at that point.


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## RocketNJ (Jul 29, 2003)

ok Mark, I'll try that today. I've bypassed the preamp but did not reboot/rescan. 

Again the tv's ATSC tuner does not have any problems. It's as if the 921 tuner is not able to correctly compensate for any fade in the signal.

Dave


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## redshift (Feb 14, 2005)

I want to backup back up RocketNJ's observations on OTA on the 921. I have LOTS of problems with wildly fluctuating signal strength. When using the OTA tuner in my TV all of my HD channels come in without issue. When I use the OTA tuner in the 921 I get lots of drop outs and "Acquiring Signal" types of messages on cetain channels. My 811 doesn't seem to exhibit this behavior.


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## Mark Lamutt (Mar 24, 2002)

redshift - I have the same advice for you. Delete your OTA channels, reboot and then rescan them. I know of one instance on my 921 where one of my Denver stations screwed something up in the PSIP transition that caused the fluctuating signal strengh issue. A delete-reboot-rescan solved that one for me. That's why I'm suggesting you try this first.


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## pdlittle (Jan 25, 2004)

Mark Lamutt said:


> redshift - I have the same advice for you. Delete your OTA channels, reboot and then rescan them. I know of one instance on my 921 where one of my Denver stations screwed something up in the PSIP transition that caused the fluctuating signal strengh issue. A delete-reboot-rescan solved that one for me. That's why I'm suggesting you try this first.


Mark,

I also have an OTA channel (KGAN CBS) that just will not maintain a reliable lock. I talked with E* 2nd level support about a possible problem with the OTA tuner and they told me that if the tuner is receiving and locking on to any of the stations then I should consider it working properly. I described the condition in great detail to the tech and she seemed to understand the issue. Her only recommendation was that I delete the station and add it back just as you have described. I followed those instructions and it made no difference at that time. I'll give it another try tonight. I know the stations are all tweaking the PSIP data so hopefully they will have made a correction that will stabilize the channel.

The interesting thing with my channel is that there are two other stations on the same tower that are sharing the transmitter with this station and the other stations have never exhibited the condition. KGAN is always having to re "Acquiring Signal" even though the signal level is very strong 80% to 95% typically. The signal level does bounce around a little for this station, but only slightly more than the other two stations. I have been ruling out a multipath problem, because I would think that if I had the problem with one of the stations on that tower I would have it for the other two.

Paul


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## RocketNJ (Jul 29, 2003)

Hi Mark,

I've bypassed the antenna preamp at top and bottom, deleted all local channels, rebooted by holding down power button on 921 unit, then rescaned after bootup. Still having difficulty with WCBS, WNYW (FOX), and WPIX (WB) out of NYC, They are broadcasting off Empire State Building along with WNBC, WABC, and WWOR (UPN). 

I do not have any trouble with jumping signal strength on WABC, WNBC, or WWOR. 

I switched to the tv's ATSC tuner and while the signal was a little lower on WCBS and WNW compared to WNBC and WABC, it was not jumping, just lower. WCBS and WNYW give me around 68 on the tv ATSC tuner while WNBC and WABC are around 83 (on a scale to 100).

Clearly the 921 ATSC tuner is having trouble syncing to some of the channels. Since the signal strength is not varying on the tv's tuner I would think it is not a multipath issue. It almost appears to be an AFC issue or the 921's tuner unable to maintain frequency lock.

Please let me know what else I can try. I'd be more than happy to help Dish engineering resolve this problem as I cannot record hi def locals on the affected channels (unless I would want to watch "acquiring signal" or watch artifacting).

I have the ability of measuring the signal strength of the various channels with a spectrum analyzer if necessary.

Thanks
Dave


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## Mark Lamutt (Mar 24, 2002)

Dave, email me your receiver CAID number, smartcard ID number, a phone number where the 921 team can contact you, and what we've gone through and tried here in the way of troubleshooting. Copying and pasting the above posts is fine. I'll send the info to the 921 support team, and they'll call you.


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## pdlittle (Jan 25, 2004)

Mark Lamutt said:


> Dave, email me your receiver CAID number, smartcard ID number, a phone number where the 921 team can contact you, and what we've gone through and tried here in the way of troubleshooting. Copying and pasting the above posts is fine. I'll send the info to the 921 support team, and they'll call you.


Mark and RocketNJ,

I would appreciate it if you could follow up with how this turns out. It appears several of us are experiencing a similar issue.


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## JM Anthony (Nov 16, 2003)

pdlittle said:


> . . . The interesting thing with my channel is that there are two other stations on the same tower that are sharing the transmitter with this station and the other stations have never exhibited the condition. KGAN is always having to re "Acquiring Signal" even though the signal level is very strong 80% to 95% typically. The signal level does bounce around a little for this station, but only slightly more than the other two stations. I have been ruling out a multipath problem, because I would think that if I had the problem with one of the stations on that tower I would have it for the other two.
> 
> Paul


Paul - you're not alone. In Seattle, KING and KONG share the same tower and KONG stays locked on my 921 but about 25% of the time I'll have problems with KING and multipath - it shows a strong signal (85 or more) but jumps around between that and zero. But then there are other days and other times when the signal is rock solid.

My antenna guy tells me that the 921's meter is more a reflection of signal quality than strength.


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## RocketNJ (Jul 29, 2003)

pdlittle said:


> I would appreciate it if you could follow up with how this turns out. It appears several of us are experiencing a similar issue.


pdlittle, I'll let you know how it turns out.

Mark, I've sent you the requested email.

Thanks,
Dave


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## sleepy hollow (Aug 25, 2003)

Just for the record, I have a similar problem in Northern VA outside DC with the NBC affiliate. I believe 3 of 4 major nets are on the same tower (including NBC), but NBC jumps around and does not usually lock. 

Luckily most of the OTA sports events and programming we watch are on FOX and the other three. I have no earthly idea what's up. I am about 15 miles from the tower, according to antenna.org.


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## RocketNJ (Jul 29, 2003)

I've emailed the information Mark requested. I'll let you all know how it progresses.

Dave


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## klaatu (Dec 7, 2004)

JM Anthony said:


> Paul - you're not alone. In Seattle, KING and KONG share the same tower and KONG stays locked on my 921 but about 25% of the time I'll have problems with KING and multipath - it shows a strong signal (85 or more) but jumps around between that and zero. But then there are other days and other times when the signal is rock solid.
> 
> My antenna guy tells me that the 921's meter is more a reflection of signal quality than strength.


I am also in Seattle and experience similar problems to JM Anthony. I do not have any problem on my TV's ATSC tuner. Rock solid all the time!


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## RocketNJ (Jul 29, 2003)

Mark,

Have you heard anything from the 921 team regarding the ATSC tuner problems I'm experiencing. It is almost impossible to record OTA HD on CBS, FOX, or WB.

Thanks,
Dave


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## Mark Lamutt (Mar 24, 2002)

You were scheduled for a call yesterday from them. Did you not receive it? If not, please email me your phone numbers again, and I'll forward it to them a little more forcefully.


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## RocketNJ (Jul 29, 2003)

Hi All,

Got an email from the 921 team and have learned a few new things. The signal strength indicator is more of a quality indicator and not a true signal level indicator.

With that in mind I started trying to improve the quality of the signal. My OTA antenna system is comprised of a 14 dB gain yagi antenna and a 28 dB gain mast mount preamp (with a dc injection block inside the house). What I found was the 921 tuner was receiving too strong of a signal. I wound up installing two 6 dB attenuators (Radio Shack 15-1257 @ $3.99 each) between the preamp power supply and the tv. This reduced the overall gain of my antenna system. The signal indication on CBS and WB are now at 125 with no fluctuation and FOX is 116 with fluctuation to 112. I've watched two hours on CBS OTA HD last night with no loss of signal or pixelation. Also just watched an hour on FOX without a problem.

So, for those experiencing fluctuating signal, intermittent momentary loss of signal, and pixelation here's some pointers.

First, check the signal indication on channels you are experiencing problem with. If the peak signal isweaker (not at 110 or above) then you may need to improve your antenna system (more gain or mast mount preamp). Also check the antenna orientation. If you live in an area with large buildings of hills you may be getting multipath reflections. Adjusting the antenna direction to minimize those reflections is the first step.

Second, for those with a very strong signal but experiencing the fluctuations in signal you may be suffering from the problem I had. Try one or two of the attenuators from Radio Shack. They've got an F male connector on one end and an F female connector on the other. They go righ inline with the antenna cable to the 921 OTA input. If you have a preamp, the attenuators should be located at the back of the tv and not between the preamp and power supply.

I hope this helps! I'm happy I can record OTA HD again. 

Thanks to Mark for forwarding my emails to the 921 team and thanks to Allison from the 921 team for the feedback to help resolve my issue.  

Dave


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## JPC (Feb 8, 2005)

Dave,
I'm glad to hear that the 921 team responded and that you've fixed your problem. I've been experiencing the same problem, and my latest plug-out reboot fixed it for 2 days and now it's happening again. I have to wonder why a reboot would (temporarily) fix a problem being caused by a hot signal or poor signal reception. I'm not convinced that the OTA tuner is not at least partially to blame. I'm going to try the attenuator idea, but I'd appreciate it if someone could explain how this problem could be completely unrelated to the OTA tuner in the 921, given the fact that a reboot made it go away.
JP


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