Ah yes, I was thinking of the bandwidth of the CW filter - not the center frequency! But a simple add on bypass switch could possibly be used to link out the filter when receiving WSPR...
That would work. You would only get about 25dB unwanted sideband cancellation at 1500Hz but for WSPR that should be fine. ?
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However, would I be right in thinking that in beacon mode the receiver is not active? My understanding so far is that in beacon mode the unit performs much like the U3S, doing its calibration etc, so would that mean that there is no active receive during the downtime between WSPR Tx periods? Or is the receiver active but just not shown on the LCD? I guess there would be a need to set the receive frequency differently also to the Tx, I suspect this would require a firmware mod?
In the beacon mode, the receiver is active in between TX periods. The receive VFO is offset from the transmit frequency by the "CW Offset" parameter (default 700Hz). That presents a slight difficulty for 1500Hz WSPR since the CW Offset parameter is a 3-digit number so has a maximum value of 999Hz. I can easily change this with a small change to the firmware, that I will make immediately.
The GPS serial data parse (for real-time clock setting and Maidenhead Locator grid square), and the 27MHz reference frequency calibration, all take place immediately after the end of the WSPR transmission. The time required for the parse and frequency calibration is 7 seconds. Therefore it is all over by the start of the next minute - either for another WSPR transmission or preferably (since continuous WPSR TX in every slot is very anti-social) for some RX time.?
The calibration etc in the QCX is not the same as the U3S.?
