[Elecraft] K2 Tuning 'glitches' every 5 Khz

Sun Feb 23 18:27:00 2003

Hi Brendan,

I've noticed that too. It seems to only be noticeable on mine when there is
a very strong signal somewhere in the band, like a crystal calibrator. It's
probably due to the transient response of the PLL when it's reprogrammed
across a 5KHz boundary.

The DAC voltage and the countdown value in U4 change at the same time, so
the tuning voltage to the varactor diodes momentarily sweeps across a
different value from the final steadystate value. This causes a stray signal
to appear in the  passband for an instant.

This  glitch can occur even when your crystal has enough pulling range, but
you do need to check the REF OSC DAC voltage range anyway, U6 pin 1 on the
RF board.  This voltage should be greater than 0.25V and no more than the
voltage at U6 pin 8 less 0.25V.  This should apply across all bands after
running CAL PLL.

73/ Bob - AG5Q

----- Original Message -----
From: "Brendan Minish" <[email protected]>
To: <[email protected]>
Sent: Sunday, February 23, 2003 2:18 PM
Subject: [Elecraft] K2 Tuning 'glitches' every 5 Khz

> My K2 has little glitches every 5 Khz, these are not terrible by any means
> but are irritating when tuning around.
>
> I suspect that these are only present since I carried out the stability
mods
>
> I have rerun CAL VFO but this has not gotten rid of the glitches
> any ideas on how to get rid of the glitches ?
> 73
> Brendan EI6IZ (K2/100 1642 )
>
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