[Elecraft] K2 (ssb)

[Ron D'Eau Claire]

Yes.

Minimizing the transmit bandwidth improves the signal/noise ratio for a
given output power, whether it's done with an I.F. filter, as in the K2, or
an audio filter system such as an equalizer in the K3. As the transmit
bandpass is reduced, the position of your voice audio spectrum in that
bandpass becomes more critical. 

The K2 doesn't have an audio equalizer built in. It does offer a narrow
filter that is about at the minimums for good SSB intelligibility (2.1 kHz).
That gives the K2 excellent SSB "punch" provided the audio bandpass is
properly positioned in that bandpass. The trade-off is between overall
fidelity and "punch". Narrowing the bandwidth necessarily cuts off the highs
and lows in the audio spectrum, making the signal sound less "natural" but,
when set up properly, it can be heard and understood in situations where a
wider-bandwidth signal might not. 

Adjusting the BFO frequency in the K2 allows you to place your voice in the
optimum spot in the filter bandpass, but the adjustment is sensitive,
especially when using the narrow 2.1 KHz I.F. filter in the K2. That's why I
reported earlier that I cannot do that looking at a Spectrogram display.
After "roughing it in" with Spectrogram, I have to listen to the signal
while adjusting the position of my audio in the passband by adjusting the
BFO frequency. 

The K3 uses a more typical I.F. filter bandwidth (2.6 or 2.7 KHz) so the
exact position of the audio spectrum in the filter bandpass is less
critical, just it is in a K2 equipped with the wider filter bandwidth. In
the K3 you can use the Transmit Equalizer to actually shape the audio within
the filter bandpass for best sounding signal with your mic and your voice as
well as roll off lows and highs to help reduce the bandwidth, if you wish.  

In any case, I always make the final check of my audio by recording my
signal, then playing it back, since it's impossible to hear exactly what we
sound like in 'real time'. 

Ron AC7AC


-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of David Cutter
Sent: Friday, February 08, 2008 11:32 AM
To: G4ILO; elecraft at mailman.qth.net
Subject: Re: [Elecraft] K2 (ssb)


My K3 has yet to arrive, but, wouldn't this "punch" come from the voice 
equaliser?  ie setting the voice band to suit your own voice to peak in the 
right place.

David
G3UNA

>
> If I wanted to be controversial (what, me?) I'd say that the K2 SSB 
> audio
> is
> better than the K3's. The K3 sounds cleaner perhaps, but the K2 is
> definitely punchier, which matters when you're running QRP.
>
> The K2 does take a bit of setting up to get it sounding right, though. 
> The folks who are complaining may have been those who didn't do it 
> properly.
>
> -----
> Julian, G4ILO  K3 s/n: 222 K2 s/n: 392
> G4ILO's Shack: www.g4ilo.com
> Zerobeat Ham Forums: www.zerobeat.net/smf

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