[Elecraft] K2 microphone advice

[Don Wilhelm]

Darwin,

The current production K2s have a SSB filter bandwidth of 2.4 kHz - that can
be easily changed to a 2.6 kHz width by changing the capacitor values (most
easily done before the crystals are mounted) - Elecraft has a kit with the
proper value capacitors.  Proper alignment of the filter passband in the
audio spectrum will also go a long way toward obtaining a 'natural sounding'
audio response.  In addition, those K2s that do not have proper dial
calibration may sound a bit 'wimpy' on an SSB roundtable net if one just
tunes it to the designated frequency and does no more fine tuning of the
rest of the folks in the roundtable - the K2 dial may not read correctly
unless it is properly calibrated after setting the 4 MHz reference
oscillator.  If you want details on how to accomplish this task, check out
the K2 Dial Calibration article on my website http://w3fpr.qrpradio.com .

The older KSB2 did have a 2.1 kHz filter width which gave more SSB power
when QRP.  Yes, it did not give great 'broadcast sounding audio', but it is
quite effective.

As an aside, I can recall when the Collins 1.8 kHz SSB mechanical filter was
the thing to be desired by the SSB crowd with adequate bucks to buy the
filter - it gave great communications intelligibility (albiet at the expense
of fidelity) - I just shake my head in wonder about how expectations have
changed over the years.

73,
Don W3FPR

> -----Original Message-----
>
> I haven't used or worked a K2 on SSB but I get the impression it is not
> the best audio.  Seems to me the issue is not the mic, but the 2.0 KHz
> SSB filter.  That's pretty narrow and won't give good hi-fi (or mid-fi)
> SSB.
>
> How hard would it be to increase the bandwidth of the SSB board's filter
> to 2.6 KHz or so?  I'd love that.  If I want the bandwidth limited I can
> do it with an outboard parametric EQ.
>
> - Keith KD1E -
>