[Elecraft] El-Cheapo signal source 7.3mhz

[Don Wilhelm]

Duane,

I am not certain how you are setting the BFOs using a single frequency 
signal.

Usually, having a single frequency source just confuses things because 
the filter center is difficult to discern with a single frequency source 
- you must plot the response of the filter bit by bit to create a plot 
of the filter passband shape.  This is what a Spectrum Analyzer with a 
tracking generator will do automatically.

It is much easier to use a source of broadband noise (like the Elecraft 
NG-1) and view the passband position using Spectrogram.  The FFT based 
Spectrogram display will show you not only the passband position, but 
also the shape of the passband.  When the passband is centered at your 
favorite CW pitch, it is correct.  Once you have tried it, you will 
never go back to plotting a point-by-point spectrum of the filter 
response.  The only drawback to Spectrogram for general filter analysis 
is that the filter response must be converted to the audio range, but 
the K2 (or other receiver) has a detector than does exactly that task, 
so no additional equipment is needed other than the noise generator and 
a connection to the computer soundcard.

73,
Don W3FPR

dw wrote:
> I needed to make a Digi-Key order last week, so I added a little clock
> osc to the order.
>
> Digi-Key PN: X208-ND, 7.3728Mhz Clock oscillator $2.13
> Dug up 3 470pF caps and a couple of 1uH chokes for a low pass on the
> output.
> Added small lm7085 regulator and put it into a small plastic box with 1
> foot antenna wire sticking out.
> Its rock solid from start-up.
>
> I used it last night to check and reset my K2 BFO filters.
>
> I know others really prefer the spectrogram software, and some day I
> will try that but for now I'm really happy setting the K2 BFO filters
> with the little signal generator.
>
> Duane
> N1BBR
>   
>