[Elecraft] KSB2 sidetone?

[Don Wilhelm]

Chris,

I cannot relate 'sidetone in the headset' with SSB operation.  In CW, 
there is a sidetone presented to the headphones or speaker which follows 
the keying, but there is nothing of that sort for SSB.  If you lost your 
CW sidetone while using the K2 memory, that is quite another matter.  
The K3 does provide a means of monitoring the transmitted audio (but 
that is not a sidetone), but the K2 does not - an external receiver with 
a short antenna while the K2 is operating into a dummy load can be used 
to listen to your transmitted audio.

As far as the 'murmur', please try to be more descriptive - I can only 
guess that it might be either room noise pickup by the microphone or it 
could be incomplete carrier suppression or possibly some sort of RF 
Feedback due to 'RF in the shack'.

If you have an oscilloscope or other means of detecting a low level RF 
signal, you can set the carrier balance pot with more precision than by 
using the method described in the manual.  Do not connect a microphone 
but do connect a key or paddle - connect the 'scope or other detector 
across a dummy load.  Then go to LSB mode and close the dot paddle or 
handkey and adjust the carrier balance pot for minimum carrier - switch 
to USB and check the carrier balance again - you may have to go back and 
forth between LSB and USB to obtain the lowest compromise setting for 
both sidebands.  Properly adjusted, the K2 carrier balance is excellent.

You may also want to re-check your OP1 passband setting using 
Spectrogram.  It is important to place the low frequency corner (-3dB 
point) of the passband close to the 300 Hz point for both LSB and USB.  
If you have the stock 2.4 kHz SSB filter, set the Spectrogram markers at 
300 and 2600 and center the passband between those markers and it will 
normally be correct for both transmit and receive.  See the filter 
setting information in part 3 of my K2 dial calibration article on my 
website http://w3fpr.qrpradio.com for additional information about using 
Spectrogram for setting the SSB filters.

73,
Don W3FPR

Chris Kantarjiev wrote:
> Even though I built and installed a KSB2 a year or so ago, this week
> is the first time I've actually used it. I have to admit, phone
> operation is sort of fun, though I'm not likely to spend much time
> outside contests doing it - altogether too much like a telephone.
>
> One question: there doesn't seem to be any sidetone in the headset
> when I transmit. I made some recordings of my audio output (to
> play back for W7GH, who was also testing out his KSB2), and we
> both noticed that there is some ... murmuring when I'm transmitting,
> but nothing intelligible.
>
> I thought the lack of sidetone would be an issue, but it doesn't
> seem to be. Still, I'm curious - what's the murmuring? Should there
> be audible sidetone?
>
>