Don't have a U3S to test with here, but the normal drive chain is:
K3 (10.137 khz out)
xvtr (137 khz out)
137 khz LPF
Doubler (trifilar xfmr, BAT41 schottky diodes)
Tuned filter (parallel coil + cap between signal and ground)
LM311P squarer (80-90mV level detect)
4013 flip-flop
MCP1404 driver (4.5A) with ability to key supply line (per G0MRF circuit)
I'm primarily interested in CW, WSPR, JT9...
CW not a problem with a constant carrier and keying the driver. Don't
intend to run Opera but understand Jay's method of doing so.
So running the exciter at 2x excitation and WSJTx at 2x tone spacing
works flawlessly? Guess that's an option...
But, going back to what Rik was eluding to... a hanging driver output.
Can anyone capture the end of the RF envelope from a U3S when running
WSPR? Just a thought, perhaps the RF is ending exactly at a zero
crossing, whereas a typical PC/soundcard + exciter may not be and that
is causing this issue. I can't imagine anything else that would be
different; after all the filtering and processing, my driver outputs to
the FET gates are very clean.
73 Eric NO3M
On 2/26/19 6:18 AM, Chris Wilson wrote:
Hello N1BUG,
Just to add things were MUCH worst using a X2 multiplier circuit
(Jay's). I now use an exciter frequency of X2 direct both from the
U3S, and as of late X2 from the TS-590 into a simple squarer and use
WSPR in the "Advanced" X2 mode to correct the WSPR tones. No issues at
all with either. OPERA is a no no as of this time, it is a FET killer
:) Don't know why though. It would be great to get to the bottom of
all this!
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