[Elecraft] [K3] 'Birdies' on 6M when adjusting filters

[Wayne Burdick]

Hi Mike,

Virtually all high-level signal sources (like the synth in a superhet receiver) have a few birdies, and it's possible you've found one. Typically they are of the "fast-tuning" variety, indicating they're related to a high-order harmonic of the VFO frequency. 

We painstakingly swept all ham bands using the KSYN3A to make sure that the few birdies present were all very low in amplitude, so they'd be masked by band noise. However, it isn't practical to sweep all bands with all filter bandwidths. 

Fortunately we provided a firmware-based tool for just this occasion: the CONFIG:SIG RMV menu entry. Using this menu entry you can "map out" most fast-tuning birdies on a per-band, per-mode, per-filter-setting basis. 

There are instructions for SIG RMV in the K3 owner's manual. We recently improved the instructions when we wrote the K3S owner's manual, so you might want to use those instructions instead.

Let me know if this helps.

73,
Wayne
N6KR



On Jun 20, 2015, at 12:23 PM, Michael Eberle <mteberle at mchsi.com> wrote:

> A few days ago I installed the new KSYN3A modules in my K3 along with the KXV3B modules.  I am running FW Rev 5.26.  I was at 50.267 running JT65 with no problems and the BW was at 2.8 KHz - the low cut at 0.1 and the high at 2.9.  When I adjusted the low end up to 0.3 a 'birdie' all of a sudden appeared toward the low end of the audio pass band along with a corresponding spike on the P3.  As I adjust the low cut up, each time the spike jumps further up the audio pass band.  As I adjust the cut above 0.8 the spike keeps moving up out of the audio pass band.  I can see it moving up the spectrum on the P3.
> 
> With the VFO at 50.276 and the low cut at 2 KHz the spike appears at about 50.285 as measured on the P3.
> 
> Not sure if it has anything to do with the new synth modules or the KXV3B.  I turned the preamp off but it makes no difference except for the background noise.  I tried the same thing on 10 and 12 meters but it does not happen on those bands.
> 
> Thanks,
> Mike - KI0HA
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