Alan, I'm waiting to see if there is comment from Ian about Hans
observation regarding the grabber screen, that potentially shows
insufficient time between the QRSS transmissions for the calibration
to work and also means the park mode would essentially be off when
it is needed for a minute or two before a transmission starts.? That
would shed more light on both the frequency accuracy and the
functionality of the park mode.? However, it is quite possible that
Ian does have sag on the synth IC supply despite using "decent 3A
power supply" and a separate regulator on the FET PA.
I haven't seen the rapid drop at start, but I've never had a U3S on
28 MHz and (usually) have the settings for Frame Start, Cal Time,
and Park mode operating in harmony.? The only time I ventured above
14 MHz with a U3S was to try one as a replacement for my 6m Beacon,
but I used the OCXO kit for the synth on that.
73, Bob? ZL1RS
On 1/12/2017 8:17 PM, Alan G4ZFQ wrote:
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No idea why the transmission might appear
to be 20Hz off.?
Bob,
My interpretation is that at the very start of TX the frequency is
not far out.
The trace shows a rapid drop maybe 20Hz from the exact frequency
then not much variation.
That is why I suggested a local RX with no PA voltage to eliminate
any possible 5351 voltage drop.
Ian does not seem to have one?
I've never had any such problems, do you consider the rapid drop
to be normal?
73 Alan G4ZFQ
The 20 240
Cal Time setting should set the U3S to
within a couple of Hz at 28 MHz ... but now the Ref Freq has
settled you might try something a little finer, like 01 240?
(and as above, 240 is longer than is probably necessary).
