Jerry,
True.
Just pointing out that the RigExpert was perhaps a poor choice as
a frequency reference, and with no to a little effort there are
choices.
With a bit more effort, still
with a stock BiTX before V2 arrives.
Plenty sketches out there that lock a Si5351 to GPS 1PPS, that's
accurate enough for WSPR which has the tightest requirements to
frequency accuracy of the current digital modes?
Gene Marcus to name but one, if anyone
wants pointers for code.
Alan
On 29/09/2017 16:10, Jerry Gaffke via
Groups.Io wrote:
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If you calibrate
from a broadcast station on the air, it must be a station near the
desired operatng frequency.
The calibrate scheme must deal with a fixed additive error in the
BFO
plus any error in the VFO from the si5351 that is proporional to
the error in the 25mhz reference oscillator.
The compromise made in V1 firmware is o assume it is all additive.
Only once Allard comes out with V2 firmware with the BFO driven
from the si5351's CLK0
will it be advisable to calibrate from something out of band, such
as WWV.
The 41m broadcast stations are usually accurate enough, and
usually on even 5khz increments.
On Fri, Sep 29, 2017 at 06:11 am, Alan de G1FXB wrote:
If you have a digital rather than the
analogue VFO variant, could you not temporary jumper across
the BiTX input BPF and see if you can receive one of the off
air frequency standard transmissions.? Costs
nothing more than a piece of wire and a few minutes?
Alan de G1FXB