[600MRG] RBA's and RAK's

[Rudy Severns]

I have both RAK and RBA receivers and there is  a reason why WSPR reception 
may be a problem.  With WSPR the audio output to the sound card is in the 
range of 1400 to 1600 Hz.  Both the RBA and the RAK have very good audio 
filters designed to suppress audio tones above 1200-1300 Hz.  In the RAK 
there is a audio tuning switch which lets you tune the filter from 450 to 
1300 Hz but the filter attenuation drops quickly so you may have some 
problem with WSPR.  I'm taking this information from the manual, I haven't 
had a chance to actually measure the filter responses but I know in the RBA 
the filter is pretty sharp even in the "broad" position.  My problem with 
the RBA is that the filter, when in the narrow band position, is centered at 
1 kHz.  This is a problem with my hearing which is much better somewhat 
lower in frequency.  I'm looking at modifying the filter to suit my needs 
for CW but I don't know if I'll fix the WSPR problem.  I haven't had a 
chance to look closely at the actual response.

Why you might have a problem with a BC-453 I have no clue.  I don't think 
they have the narrow audio filters.

73, Rudy