Prototype of the high performance SSB filter |
SSB filter response |
This filter is using 3rd
order active high-pass and 7th order passive low-pass with three elliptic
zeros.
The design goal was to get
better filter compared to original active filter used in my direct
conversion TRX.
Th very first prototypes
were contructed with single ended passive coils, but they picked up too
much interference.
The filter shown here is
using coils differentially to avoid the magnetic interference and the results
are very good.
- approx. 20 dB lower noise
=> 20 dB better dynamic range
- much better shape factor
(2.6 => 1.77)
Short form performance
Band width 2.4 kHz @-6dB
see
response
Good shape factor 1.77 (-60dB
/ -6dB)
Insertion loss 0 dB
Ultra low noise, total output
noise only 0.8 uVrms (300 Hz...3 KHz) see
output noise density [nVsqr(Hz)]
Very high dynamic range
130 dB
Very good stop band rejection
> 90 dB
TOKO 10RB inductors are used
in the prototype
See
schematics
Listen
a sample SSB recording during a contest in 80 m band
Listen
a sample SSB recording during a contest in 40 m band