Originally Posted by
DDaveBB:
“They're all doing it! As soon as my de-soldering braid arrives I'll be joining you.
Question for Radioredcat and Brumlad36 - with the unmodified filters do you find that the selectivity is 'off-centre' - with my unmodified Sony and my unmodified Yamaha I notice(d) that tuning 50kHz low loses a lot more of the signal than tuning 50 KHz high. On the Sony this has the definite advantage that RDS still comes through if I tune 50KHz up to reduce adjacent channel interference.
After modification the same thing - but with a more rapid fall off. So I didn't go too overboard trying to match filters on the Yamaha in the hope of getting it symetrical. (And I couldn't swap filters about on my modded Sony 'cos I didn't use sil sockets
).
Please post what you find to be a good compromise between better selectivity and still maintaining reasonable RDS response.
David
Sittingbourne”
Hi David / Andy,
I've spent a few hours mixing and matching ceramic filters, using the SIL sockets I fitted yesterday.
The best combination for me seems to be as follows ->
Filters 1, 2 & 3 (wide) = 150Khz (x3)
Filter 4 (narrow) = 110Khz (x1)
I also adjusted the "Stereo Level" and "Narrow Gain" controls. These are now both set to maximum.
I find that If the "Stereo Level" is adjusted lower than maximum, the RDS is lost on semi-strong stations.
Leaving adjustment set to maximum gives the best chance of getting RDS, but means that weak stations "break" into hissy stereo (rather than staying in mono). Simply switch the receiver to mono to overcome the hiss.
More importantly, I find the "Narrow Gain" control is best set to maximum (using the new 110Khz, narrow filter).
This is a change compared to when the original (wider) filters were used.
On a weak station (with receiver set to narrow band IF and mono), I now find that the "Narrow Gain" adjustment produces the best results when turned to maximum. It used to give best results whilst backed-off a little from maximum (when the original filters were used).
Andy,
I would imagine that in crowded-band conditions such as where you live, a set of 110Khz filters would be ideal for digging out the DX, between all the powerhouse stations.
I didn't try all 110Khz filters in the ST-SB920, because for my needs, the above combination gives enough selectivity (BBC R1, 97.9Mhz from Sutton Coldfield, next to Culture, 98.0Mhz from Lille), whilst still letting through RDS.
You can use your Denon with RDS Spy and convert your Sony with 3x 110Khz filters for best DX.
Chris.
PS. David,
Issue concerning "off centre" filtering. I noticed this (sharper cut-off below, than above a given frequency) before changing the filters, but since changing them, it's only happening very slightly. Tuning seems to be pretty well spot-on.