TGSL EDU Mod

[ashefr10]

ok , R13 and R14 rather ?

[ashefr10]

hello the mods does not work on my tgsl with the NJM and changing resistors R13 and R16 to a tier of their value, I can not properly adjust the ground effect.

[Davor]

If you reduce all resistors in feedback of a NJM2068 by a factor ~3, you reach the same gain (give or take) and the noise also gets reduced. At about 4nV/sqrt(Hz) of NJM206, and a loaded coil Q factor, you can replace 4k7 resistors with 1k5 or down to 1k, and replace the 220k resistors with 68k or 47k respectively. Either way, you need to replace both pairs of resistors, and chose tightly matched ones, say 1%, to further reduce wet grass effect.

[ashefr10]

ok, changing the 2 pairs of resistors 1,62k and 75 k that actually works with the NJM but I do not win in depth detection.

[Davor]

But you win with less chatters, and a possibility to increase post-mixer gain.

[ashefr10]

yes, less noise but be what one can gain really in-depth by modifying certain values or certain components?

[Davor]

When you gain 6dB S/N by lower noise, by "virtue" of the 6th power law you gain 1dB in distance, or 25%.

[Bobman]

Hi Davor,
I am new to this, what is 'loaded coil Q factor' please?