Info on Charleston SDR with 78.6MHz

[Terry Fox]

I now have a Charleston Receiver with the incorrect oscillator frequency 
of 78.6MHz installed (the correct one is 76.8MHz).  I can verify that 
when this is done:
1.  The frequencies are displayed approx. 164kHz low.  In other words, a 
signal that is actually at 7.150MHz will show up as being at 6.986Mhz 
instead.  A signal really at 7.164MHz will be displayed at 7.00MHz.

2.  The spectrum is NOT inverted.  Tuning a signal generator up in 
frequency causes the signal displayed in Quisk to go UP the spectrum 
display, as it should.  Also, LSB signals demodulate properly on 40M.

So, it appears that anyone having spectrum inversion issues must have 
the older version of the FPGA code, as the incorrect oscillator does not 
cause that, and it is very difficult to create spectrum inversion any 
other way (in the hardware).  Of course, messing with the receive 
software can also cause this.  I have a new version of the FPGA code 
that blinks LD7 at about a 1Hz rate, just to confirm it is OK.  I can 
send it to anyone that needs it.  Bill Fenn has a copy, and it will 
eventually be up on the AMRAD web site in the SDR/Charleston area.

Terry
WB4JFI