[Elecraft] 6m birdies and K3S and/or new synth boards

[Joe Subich, W4TV]

The spur also changes with bandwidth.  In my K3 it happens to fall at
50.279.00 with FC=1.50, BW=2.80 in DATA_A when the rig is at 50.276.00.
When going to FC=2.20, BW=4.00 the "spur" moves to ~50.285.5 and in
USB "NORM" it falls at 50.275.71 (zero beat).  Again, this is fortunate
in that the spur is equivalent to a -96 dBm signal as measured on the
P3 and would be a killer if it fell "in band".

I see additional (bothersome) spurs at 50.047.57 (-100 dBm), 50,082.72
(-116 dBm), 50.095.32 (-119 dBm), 50.102.04 (-116 dBm), 50.110.52 (-118
dBm), 50.111.65 (-120 dBm), 50.112.78 (-120 dBm), 50.150.26 (-110 dBm),
50.193.57 (-103 dBm), 50.222.56 (-119 dBm),  50.351.35 (-119 dBm),
50.390.82 (-119 dBm), 50.393.90 (-110 dBm), 50.435.85 (-119 dBm),
50.465.09 (-120 dBm), and 50.486.11 (-120 dBm) - frequencies are zero
beat in USB with DSP = norm.  Measurements were made with dummy load
and PRE_1 in K3 s/n 1450 with 2x KSYN3A and KXV3B.

"Bothersome" to me is > 6 dB above the receiver noise floor under the
measurement conditions described.  I have not attempted to catalog
spurs on the other bands.

73,

   ... Joe, W4TV


On 2015-06-25 9:14 AM, Ken_ke2n via Elecraft wrote:
> My K3 with the new synth (and upgraded DSP board) has an unfortunate "birdy"
> on 50.276 (unfortunate because this is the JT65 calling frequency in the
> US).  I know it is a DSP-type artifact because the pitch of the birdy
> changes with the IF Shift control.  The IF shift control does not change the
> frequency of the signal, just the birdy. This phenomenon is actually useful.
> By shifting the center frequency to 1.35 kHz I can move the spur down to
> zero beat. And, like all spurs, the pitch of the spur changes a lot faster
> than the tuning rate of the radio. The pitch of the spur also varies with
> the setting of the crystal filter offset (mine is set at 200 Hz).
>
>
>
> -----
> 73
> Ken
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/6m-birdies-and-K3S-and-or-new-synth-boards-tp7604211p7604287.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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