Info on Charleston SDR with 78.6MHz

[Frank Gentges]

Terry,

This clears a lot of stuff up.  Thanks for tracking it down.

I am headed out for the AMRAD WMAL transmitter tour.

Later,

Frank

On Mar 17, 2011, at 1:05 AM, Terry Fox wrote:

> 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
> 
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