[Elecraft] Strange K2 Behavior?

[Geoffrey Mackenzie-Kennedy]

With respect Kevin the 'culprit' responsible for this birdie in my K2 is the 
(LO + IF) / 2 spurious response of the receiver which can 'hear' the PLL 
reference oscillator. When the receiver is tuned to 14.360 MHz the frequency 
of this particular response, assuming a 4.914 MHz IF, is  (19.274 + 4.914) / 
2  = 12.094 MHz,  moving down to 11.914 MHz as the receiver is tuned down to 
14.000 MHz.

73,
Geoff
GM4ESD


Kevin W9CF wrote on Friday, October 17, 2008 at 8:29 AM

> Mine does that too. The VCO for a frequency around 14.360 MHz should
> be running aabout 19.274 MHz and the reference oscillator runs at about
> 12.096 MHz.  2*19.274-2*12.096 = 14.356 MHz, so that seems to be the
> culprit. It pops in because of the way the VCO is tuned. When you get
> to the edge of the fine tuning, the U4 tunes the VCO to the next 5KHz
> coarse step and U5 changes the reference oscillator back to the beginning 
> of
> a fine step. For the previous coarse step the birdie is not heard, but for
> this coarse step the two
> oscillators are tuned so that it is. On my K2, with the way I have RTTY
> set up, I can hear it pop in on RTTY at 14361.5 and then it pops out at
> the next coarse step at 14366.5
>
> 73 Kevin w9cf