# AM21 vs. AM21N OTA signal strength



## cover (Feb 11, 2007)

I got a new AM21N to see if it might perform any better or differently than my older AM21s. I immediately noticed that while I can get a signal strength of 100% using an AM21 on an HR24-500, the AM21N seems to top out at 85% signal strength. It behaved as if the scale may just different and 85% is the most it will ever show. Not sure if this difference is actually is meaningful in terms of performance.

Has anyone else noticed this? Any ideas what could be behind it or if it matters to OTA reception performance?

I have a lot of trouble with fluctuating signal levels when it is windy - suspect multipath caused by large trees moving in the wind - and am hoping the AM21N might handle this better.

Thanks


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## dpeters11 (May 30, 2007)

We have been told that all the antenna circuitry is identical.


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## Scott Kocourek (Jun 13, 2009)

I can tell you that I have both the AM21 and the AM21N and the 85% is the highest the AM21N has ever shown. Even though the signal meters show different they receive the channels the same, the fringe ones are about the same quality.


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## jamieh1 (May 1, 2003)

Same here 100% on AM21 and 85% on AM21n


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## NR4P (Jan 16, 2007)

I conducted tests a while back. The AM21N will not go higher than 85. 
The lower numbers do not mean lower signal strength.
Couldn't really find any differences in performance but never tested severe multipath.
Never published this before so here goes. See attached.


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## cover (Feb 11, 2007)

Thanks to everyone for the responses. 

Assuming that 85% on the AM21N = 100% on the AM21 (and that the scales are both linear), NR4P's comparison suggests that the AM21N performs slightly better than the AM21.


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## NR4P (Jan 16, 2007)

cover said:


> Thanks to everyone for the responses.
> 
> Assuming that 85% on the AM21N = 100% on the AM21 (and that the scales are both linear), NR4P's comparison suggests that the AM21N performs slightly better than the AM21.


I'm not sure how you came to that conclusion.
All we can conclude is that the range of the AM21 was 0 to 100 while the range of the AM21N on identical stations and cabling and antennas etc was 7 to 85.

Don't confuse the 7 as better. It just may be the bottom of the range.


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## GP245 (Aug 17, 2006)

Does anyone know which chip generation is us used in the AM21 and the AM21N?

My little Hauppauge WinTV/aero-m USB receiver uses a 7th Generation chip and with the same antenna, puts my two AM21s to shame. 

I have a feeling that DirecTV chose to use the same old chip in the new AM21N as they have in the AM21. Wish it had been updated, would have bought the "N" to receive more stations.


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## Stuart Sweet (Jun 19, 2006)

I don't know what generation the chip is, but I do believe it is the same in both. The two devices don't have exactly the same hardware but it is identical. However, as NR4P points out, some AM21N's will not go above 85% in the signal meters, despite having higher strength than that.


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## GP245 (Aug 17, 2006)

Stuart, thanks.


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## bobnielsen (Jun 29, 2006)

That 85% issue sounds similar to the 77% max reading of some of the AM21s which were in the initial field testing.


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## jamieh1 (May 1, 2003)

Little bit different topic but, I have a HR20 and its tuner does not pick up as well as AM21 or AM21n.

Channel 2 WUND (digital20) will not lock on the HR20, but the AM21's it will lock in the 80s range.


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## cover (Feb 11, 2007)

jamieh1 said:


> Little bit different topic but, I have a HR20 and its tuner does not pick up as well as AM21 or AM21n.
> 
> Channel 2 WUND (digital20) will not lock on the HR20, but the AM21's it will lock in the 80s range.


The tuners in the AM21 have definitely worked better than the built-in tuners in the HR20 for me too.

If all the OTA broadcast towers were in the same direction, I would have no trouble getting strong reliable signal with the AM21. Unfortunately, one is about 100 degrees away from the others so I have to try to find a compromise position for the antenna that works reasonably well for all the stations. I think even that would be manageable if not for movement of the trees in the wind.

To add insult to injury, our NBC affiliate moved back to low VHF so I can no longer get away with a smaller UHF antenna like the Square Shooter that seemed to handle the situation better.

I was hoping that the AM21N might use a newer generation of chips to handle multipath better.


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## GP245 (Aug 17, 2006)

I believe I remember something that the Square Shooter's ability to pick up
VHF may improve when it's rotated, such as clockwise/counterclockwise.


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## cover (Feb 11, 2007)

GP245 said:


> I believe I remember something that the Squar Shooter's ability to pick up
> VHF may improve when it's rotated, such as clockwise/counterclockwise.


Thanks for the tip. The Square Shooter is great for UHF, but has been almost completely ineffective for the low VHF channel I need.


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## NR4P (Jan 16, 2007)

jamieh1 said:


> Little bit different topic but, I have a HR20 and its tuner does not pick up as well as AM21 or AM21n.
> 
> Channel 2 WUND (digital20) will not lock on the HR20, but the AM21's it will lock in the 80s range.


I would agree the AM21 is a bit better than the HR20, particularly for multipath.

What does the HR20 show on the OTA sig strength meter when Ch 2 is selected? And does it fluctuate alot?


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## TomCat (Aug 31, 2002)

NR4P said:


> I conducted tests a while back. The AM21N will not go higher than 85.
> The lower numbers do not mean lower signal strength.
> Couldn't really find any differences in performance but never tested severe multipath.
> Never published this before so here goes. See attached.


These numbers seem to indicate that lower numbers are improved with the N, and higher numbers are lower, generally speaking. This is only speculation, but it should mean that stations that are marginal should come in more consistently. This may be a change in AGC as well, which could mean that the N will present more-consistent power levels over the band to the DVR.

On the other hand, its possible that the raising of the lower numbers may be at the expense of the lowering of higher numbers. That would not imply a compromise, however, as the high numbers remain high enough to receive consistently, meaning it could indicate an improvement for fringe reception as a net improvement without any real penalty to reception of the stronger channels.


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## dlleno (Sep 17, 2008)

TomCat said:


> These numbers seem to indicate that lower numbers are improved with the N, and higher numbers are lower, generally speaking. This is only speculation, but it should mean that stations that are marginal should come in more consistently. This may be a change in AGC as well, which could mean that the N will present more-consistent power levels over the band to the DVR.
> 
> On the other hand, its possible that the raising of the lower numbers may be at the expense of the lowering of higher numbers. That would not imply a compromise, however, as the high numbers remain high enough to receive consistently, meaning it could indicate an improvement for fringe reception as a net improvement without any real penalty to reception of the stronger channels.


So -- other than the exterior cosmetics and the signal strength issue, what really is the "N" model all about? why the new designation?


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## Go Beavs (Nov 18, 2008)

The N probably stands for new. Although it really isn't a new design, the manufacturer probably just updated the components to ones that were more readily available and/or more cost effective.


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