OK, so I attempted to post a video demonstrating the problem I am having with this new 5555N2 I just bought, but it appears that I can not. The video showed both the noise and the signal indication on the new 5555N2 at the same frequencies, and in the same mode as 4 other radios that I compared it to.
And here's the issue:
The new radio (5555N2) displays a 4-5 S-unit noise floor at ALL times, on ALL frequencies, and in ALL modes. It is also very noisy, so it appears that it's not merely an out of alignment S-meter, because it has the loud hash noise floor to match.
The problem is, the 7610, the HR2510, the Emperor, and the 2950 all show NOTHING. No noise floor on 10 meters at night, and on the very same antenna. As well as the same Astron 70 amp power supply, and placed in the same physical location as the 5555, while testing.
All are quiet on the receive, with NO indication on the S-meter, except a one dot flicker (about a quarter S-unit) on the 7610 meter from time to time, since it is a sensitive receiver with a much better S-meter. All radios set the same. No NB, no pre-amp, no attenuation, etc...
But the new 5555N2? Loud hash and 4-5 on the meter, with same antenna, on same frequency. It was suggested that maybe the S-meter is not aligned properly from the factory, which is actually the first thing I though of too, when I first discovered this. But this is an actual (noisy) noise floor, to accompany the reading on the meter. It's unusable, except for strong signals.
I did an experiment with a friend who lives a few miles away. He adjusted the power on his radio to hit my IC-7610 at 9 S-units. Once I switched to any of the other radios (HR2510, Emperor, Ranger, etc...) I got the same signal from him, at 9 S-units, so they all agreed with each other.
Once I switched in the new 5555N2, He keyed up for me and the meter said 7 flashing 8. Now if the S-meter was simply out of alignment, and STARTING OUT aligned way to high (with 4-5 S-units out of the gate) you would think that the received reading from my friend's station would be HIGHER than it was on all the other radios, but instead, it was about 1.5 S-units LOWER, so the receive is not only showing a noise floor that shouldn't exist, it's also receiving normal signals weaker than they should be.
So if I got in the Service Menu and turned DOWN the S-meter, not only would it not get rid of the NOISE, but also anyone who should be hitting me with 9, will now be hitting me with nothing. So the S-meter is not the problem. The problem is that the radio is picking up a noise floor that shouldn't be. I guess something is internally generating that signal, because nothing external is doing it, as proved by all my other receivers.
As I mentioned in a previous post, the "Scott's Radio" guy (in one of his videos) was having the exact same issue during a live QSO that he recorded, albeit a little less (more like 3-4 S-unit) than my radio is displaying. During the day today, when all my other radios were showing a 1-S-unit noise floor on 10 meters, the new 5555N2 was showing 7!
Scott's way of dealing with it, was to use the NR turned up to 5. Which got rid of the sound from that artificial noise floor, but not the indication on the meter. Doing this is obviously not the solution to the problem, because that noise is covering weak signals, and in my case, even moderate signals during the day.
Does anyone know what could possibly account for this? This is absolutely NOT normal. In 50 years of radio, I've never had a radio behave this way. I wish I could have posted videos, but I couldn't get it to work on this site, as others have.
I really despise the idea of having to (sigh) send the radio back, because the seller states that buyer pays all return shipping, and I used up a $25 bonus on my Capital One card to buy this radio, which is forfeited if this guy doesn't exchange for another radio, and simply refunds my money. His Ebay page doesn't mention exchanges, only refunds.
So I would end up paying $30 shipping, and also forfeiting my $25 bonus that I used up buying this radio. And THEN end up buying another radio for more money, and wondering the whole time, is THIS one going to do the same thing?
What is your S meter showing with the antenna disconnected from the radio?
It sounds to me like you either have a faulty radio, or (although less likely) something in the shack that is not right.
See my videos in the previous posts. If your AT-5555Nii doesn't work like that, something is obviously wrong.
Good luck! 73