Sony ST-4950 FM/AM Tuner

General:

Around 1976 Sony company came with its ST-4950 high quality tuner on the European market.

In some respect it was a competitor to the cheaper Luxman tuners.

 

Special futures:

The Sony ST-4950 tuner incorporates special custom Sony IC - IF amps as you can see on the photo.
It has a FM 4 gang varicap on the Alps front-end. It employs 2 dual gate mos-fets in the front-end.
It has a standard Hitachi IC for stereo reception and FM demodulation is a simple standard 'ratio' diode version.
Also a LF filter block is on the pcb. No provision for Anti-Birdies.
The power supply is simple but effective. The total electronic setup is simple but effective.
It has a hi-blend switchable filter. A multipath switch is available. No bandwith switch.
AM reception is also an option.
This tuner was also issued with Dolby, this version has none but an empty space.
It is a huge sized tuner and the cabinet is 70% empty: Its made to accompany the amplifiers of Sony like the TA-4650.

User manual:

User manual in PDF click here.

 

Schematic:

Service manual Sony ST-4950 in PDF click here
This above manual is in average quality, there is a version available in HQ: you can mail me for info.

 

Modifications:

Electrolytic caps can be replaced and heatsinking of the power supply transistor can be improved.

Set the deëmphasis-compensation to 75 µS in USA and 50 µS in Europe.

 

 

Sound:

This tuner is very sensitive and easy to use, it lacks the more extensive control of most Luxmans.
The sound is great and reception is good.

 

 

© Hans Hilberink - PE1MMK ® 2003 - Last update: 15-01-2018.