AudioSonic TU-101 tuner

 

General:

Around 1970 issued tuner made by 'Hakkoh Denshi Co Ltd Japan' company Japan.

 

 

front ^ 

 

Owners manual:

This tuner is also known as model # T-1000.

Manual not yet available.

 

interior, very well built and very good pcb ^
 

Special futures:

This solid-state tuner is with DIN socket and RCA cinch output sockets.
Nice simple look tuner.
Wood case.
Well build and good parts used.
2 gang variable capacitor.
Good quality tuner with remarkable good specs.
The tuner employs all silicon transistors.
The tuner has a stabilzed power supply.
Traditional ratio detector, traditional MF section with coils.
Traditional MPX section section with coils and the 4 diodes.
AFC switch at the front, well working and usefull.

 

Back panel: 2x output sockets ^

 

Power supply problems:   

The detrimental power voltage change from 220 to 240V in the EU is no issue here: The tuner has a 230V transformer.
The rectifying in the supply section of the tuner is simple: only 1 diode is used, and only 1x 470µF capacitor.

I upgraded the secondary part of the supply to get it more up to modern standards: use a 1000µF or higher capacitor.
I measured the secondary voltage before and after stabilization and noticed that the voltage was only 7.5V, that is too low,
the old zenerdiode was worn out, while the pcb is designed for 9V operation.
So I exchanged the zenerdiode to a 10V type to get a nice stabilized 9V at the board power rail.
A few extra capacitors may be added to the power supply to get it to modern standards.

 

Solder side pcb ^

 

Specifications:

FM IHF sensivity: 2 µV at 25 dB S/N.
Capture ratio 1.8 dB.
Distortion (THD 20Hz - 15kHz) ~1% at max input voltage.
Signal/noise ratio: 50dB stereo.
Channel spearation approx. 40 dB.
AM works well.
 

 

Stereo ^

 

Schematic:

not yet available

 

 

Modifications:

Update all electrolytic capacitors, they do not meet the specs anymore.

You may replace some diodes, capacitors and resistors in the power supply and power rail.

The stereo lamp can be exchanged for a red color Led.
The scale lamp can also be exchanged by a ledlamp.

The only 2 gang FM front-end variable capacitor could have given a problem in the years from 1960 to end 1990's
when the FM band was a very busy used.
The lack of serious selectivity could ie. in cities with a full FM band make this tuner not the best choice.
Today this is not an issue anymore because the FM band is quite empty, and this tuner in all its simplicity can
outperform modern cheap FM tuners today: it is sensitive, stable and gives very good audio to your amplifier.
Of course its no match for a Hi-performance FM tuner like a Luxman T12 or T14, but it never meant to be.

 

interior after update ^

 

White version with amplifier ^

 

More info about this amplifier model WS-101: click here.

 

Sound:

The sound is very good for such a simple tuner.

 

© Hans Hilberink - PE1MMK ® 2003 - Last update: 11-06-2019.