Originally Posted by
DDaveBB:
“I've just fitted narrow filters to my recently purchased Sony ST-S311 and also taken off the clock and data signals from the smd RDS Chip to feed RDSSpy via the audio input of a PC soundcard.
I've compared the two receivers below - full service manuals for both can be downloaded from electrotanya.com - which shows in many respects the circuitry is identical or only slightly tweaked.
SB920 - conventional components throughout
ST-S311 - surface mounted capacitors and resistors except for electrolytics and fusible resistors.
SB920 - two aerial inputs
ST-S311 - one aerial input (UK model), two aerial inputs (EU model)
SB920 tuner - big
ST-S311 - tiny and inaccessible but as far as I can tell - apart from the coils it's all surface mounted components. BTW the silver fixing bolt holding the aerial panel to the chassis is soldered to the tuner can - and needs to be unsoldered in order to remove the board for modification - and re-soldered after. I presume it to provide better grounding.
SB920 - no easy access to bandwidth or attenuator and most of the other selection buttons are small and behind a drop down flap
ST-S311 - everything is on the front panel and much easier to access.
SB-920 - the front display panel has a metal shield
S311 - doesn't have a shield.
The IF layout on the S311 is much better in my opinion as all four filters are in a straight line - unlike the SB920 - so might be less likely to suffer leakage(?)
I also spent a little bit of time swopping out ceramic filters.2x150 + 1x110 and 2x150 + 2X110 showed no discernable difference in RDSSpy responsiveness - but going to 1x150+3x110 made it appreciably slower on a marginal station.
So at the moment it's running with 2x150 and 2x110.
Sensitivity? I don't know if I can tell the difference. I've no measuring equipment other than the lump between the ears
and I'm also comparing with an SB920 fitted with 3x180 and 1x110. And external noise is the limiting factor anyway. As RDSpy response time is the same I'll be putting the same filter line up that I have in the ST-S311.
The ST-S311 goes for quite reasonable amounts on ebay - and worth a look. My one is probably going to be used as a dedicated M-S receiver plugged into an old desktop PC.
David
Sittingbourne”
Strange enough, I prefer the ST-S311 albeit only one aerial input... for the simple fact that you can ADD the FULL 8 character RDS station name whearas the ST-SB920 only gives you 5 characters to add a station name.
Also... (having owned BOTH tuners) I find that some stations have better reception on the 311 compared to the 920..which is bizarre.
The only modifications carried out are to the internal 'gain' pots...with NO further added 'narrow' filters'
I am currently using a Sony ST-S361 of which is 'narrowband' and has twin FM aerial sockets and an 'Attenuator' ...albeit only a 5 character 'manual' station name display...unless of course the station is strong enough to recieve it's 8 character RDS.
I personally find the ST-S361 BETTER (and more user friendly) than the 920....only with similar quality audio to the 920.
My ONLY flaw with the ST-S311 is the 'audio' quality is not as good as the 920 or 361.