[Elecraft] SO2V mixed mode oddity

Sat Jul 23 16:31:01 EDT 2016

 > (incidently, K8UT does not notice this on his K3S)

It seems that you have not attempted to determine what is different on
your K3 and that of K8UT.

The behavior you (and VE3KI) are seeing is due to the EQ setting for
the main RX being applied to the Sub RX.  If you will select MENU:
RX EQ and press CLR for each mode (setting RX EQ flat for each mode),
you will no longer observe the behavior (audio "roll off") you have
been complaining about.  The audio roll off is most likely because
you have selected a significant high frequency roll off for CW.

Pressing B SET causes the K3 to select the RX EQ settings for the Sub
RX mode which remains in effect when you clear B SET - until you toggle
either Entry focus (position of the green dot) or TX Focus (position
of the red dot).

It is likely K8UT has his CW RX EQ set to flat or very similar to his
SSB settings.

73,

   ... Joe, W4TV

On 7/21/2016 6:31 PM, Mike Smith VE9AA wrote:
> Reported by myself (Mike VE9AA) on the N1MM+ list but described much better
> by VE3KI, Rich, below.
>
> Has anyone found a work around to mixed mode SO2V operating when the sub rx
> is on SSB?
>
> (incidently, K8UT does not notice this on his K3S)
>
> [Elecraft] [K3] Strange filter behaviour in the subRX
> <http://www.mail-archive.com/[email protected]&q=subject:%22
> %5C%5BElecraft%5C%5D+%5C%5BK3%5C%5D+Strange+filter+behaviour+in+the+subRX%22
> &o=newest>
>
>
>
> Richard Ferch Sat, 02 Jul 2016 15:43:22 -0700
>
>
>
> After a user reported problems with filter settings in N1MM+ in SO2V with
>
> one VFO in CW and the other VFO in SSB, I did some investigating. I had
>
> never tried mixed-mode dual receive before. After doing some experimenting,
>
> first with N1MM+ and then with the radio on its own, I conclude that there
>
> does appear to be a problem, but it seems to be in the K3 firmware, not in
>
> N1MM+.
>
>
>
> After some initial exploration, I ran audio spectrum analysis software on
>
> the Line Out output of the K3 with band noise input on a dead band, default
>
> filter settings and with no radio control software of any kind running.
>
> With both VFOs in SSB, the noise spectrum display is similar for both VFOs
>
> - reasonably flat (plus or minus a few dB) from 200 Hz to 2800 Hz, more or
>
> less. If one VFO is in CW and the other VFO is in SSB (or DATA A, which
>
> seems to behave the same way), the VFO A SSB plot looks the same as before,
>
> but when I use the K3's A/B button to swap VFOs, the spectrum display for
>
> VFO B in SSB looks quite different, with a more or less linear rolloff of
>
> roughly 10 dB/kHz (not per octave, per kHz) from 700 Hz to 2700 Hz. That
>
> is, at 1700 Hz the spectrum plot is down around 10 dB from the value at 700
>
> Hz, and at 2700 Hz it is down around another 10 dB. The difference is
>
> clearly audible. I can fix this by pressing the B-SET button on the K3,
>
> which restores a flat response profile in VFO B, but when I press A/B twice
>
> to swap the SSB and CW settings between the two VFOs twice, the rolloff
>
> comes back when VFO B is in SSB mode.
>
>
>
> Has anyone else seen anything like this? Is there a configuration setting
>
> that can fix it?
>
>
>
> 73,
>
> Rich VE3KI
>
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> Mike, Coreen & Corey
>
> Keswick Ridge, NB
>
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>
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