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jessie.dazzle wrote:

I live where FM program quality justifies a good tuner. Despite getting what I consider to be really excellent sound from this modded TU9900, I will one day compare it to a TU-X1. I will post my findings here.

Jessie, if you live in a place with good FM program then with a good tuner it completely redefines what high-end all about…. I never heard the TU9900 and it you lay you hams on TU-X1 it would be very interesting to learn how they compare.  BTW, here in US we have no interesting AM programming (just new and talk show) but in Europe, where everything is much closer you might have better AM programs. The TU-X1 has remarkably good AM sound – I was very surprised how far it is from what we get in car. BTW, according to Dima the TU-X1’s AM section is much more sophisticated and according to him “proper” then the TU-X1’s FM section

glaesemann wrote:

The lightning strike may have caused changes beyond the obvious damage as well. I knew a caddy who was hit by lightning and though it didn't kill him, he was never the same again either.

Perhaps it is what I was asking Ken many times. He assured me that whatever damage was done by lightning is completely rectified and there is no memory in the tuner that it ever took place.  Tell it to your caddy… :-)

Romy wrote:

After a few days of self-education and harassment of various technical people I got what I need... – the truth and the reasons why ….

Regarding the overload – here are the fragments of valuable  comments of “John A” who helped me to learn more about the problem:

“ Overload is a bitch with most of the high sensitvity vintage tuners! …

The TU-X1 meter should be calibrated in DBf and thus if aligned properly should work fine with ONE 100dbF signal.

But when you throw 2 or 3 very strong signals close together at it, then it just pukes!. I don't have overload here with my modern tuners but my vintage units will  get "hissy" when my antenna aims close to a local around 100dbF here. Keep in mind that hiss is not the only symptom of overload as some of my tuners increase sound "hard" or strident as the signal becomes too strong. 

The Kenwood L-o2T which has RF and IF AGC should work for your conditions better, but a Technics 9030 is probably best for handling overload, unfortunately it doesn't sound too great without major modds

It is inherent in the design, as it has 2 RF amps when almost all others have only one. It was designed to be a supertuner spec wise so Sansui went nuts on the RF gain to get the best "marketing" numbers (8.7dBf) where people would recognize the superiority vs their other tuners and the competitions. The high end Kenwoods and Technics used less RF gain and balanced mixers to avoid overload but had nowhere near the sensitivity as a result. There are always tradeoffs and tuner RF dynamic range was not as big a concern then as it is now.

Tandberg with their TPT3001a repeated this "tradeoff" of extreme sensitvity at the cost of overload resistance. It has around 8dBf usable sensitivity too and overloads like crazy also. In todays FM environment you would need to live way out in the boonies to use this level of sensitivity.

More recent tuners even bypass the RF amp completely in LOCAL mode (best solution) or have PIN diode variable attenuation to kill excess signal. In your current location it would have been best if Sansui had bypassed the 1st RF amp with a local mode switch. No gain = no IM distortion

Going from 5uV to .8uV is about 16dB more sensitive,so why do you need >20dB attenuation if you didn't have overload hiss before the alignment?

Going higher than 20dB attenuation may be questionable becuase you will throw away much of the quieting that the TU-X1 is capable of .If you look at the curves on the broachure you will see that your tuner doesnt get to max S/N until 70 to 80dBf, so if you have to attenuate all the way down to 50dBf you're not even close. If you are having problems with a very strong close station you don't want to listen to, a notch filter may be better.

This issue will be a problem for your more distant stations not the ones less than a mile from you. The nearby stations (within 2MHz and location) will cause frontend distortion while the distant station will be weak. Your experimentation with attenuation and antenna aiming will have to determine the best compromise. You'll have to minimize hiss and multipath for two input variables. Lots of fun tweaking!”

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