[Nodxa] Receiver frequency stability vs WSJT-X 3 SF vs Elecraft K3 and K4

[Glenn Williams]

Hi, Here's another interruption from Glenn (did I got all this
correct?):

Elecraft K3 and K4 have drift with warmup temperature on
bands like 10m that can interfere with Superfox operation.
(Effects can also occur on FST4 mode.)

Note the "F-Tol" setting in WSJT-X FT8 Superfox.  One source
says that the maximum is 100 Hz.  K3 and K4 have numbers like
5 ppm (0.5 ppm with TCXO) or .3 ppm (K4).  On 28 Mhz: 5 ppm
=> 28x5 = 140 Hz, or .3 ppm => 28 x 0.3 = 8.4 Hz.

So if you happen to run Superfox Hound at F-Tol=20 combined
with the new rule in WSJT-X 3.0.0 that you have to decode the
SF first before you can click him in and then call him, you
may have drifted outside the allowable range with temperature
warmup and you won't be able to decode him and then call him.
I experienced this problem with my 5 ppm rig. What followed
was considerable tweaking of the receive frequency trying to
net him in, and time to do that while there was a chance he
could just QRT or fade-out.

This same problem of warmup drift also will affect the DXer's
rig so he could TX slightly off frequency also.

--73, Glenn, AF8C

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