[HBR] Question about HBR BFO Waveform

[Ian Wilson]

BFOs that do not have an explicit amplitude control mechanism rely on
nonlinear mechanisms like saturation (e.g. Class C tube operation) to
operate. So the waveforms in most places in such circuits will typically be
harmonic-rich.

If you want to pick off a clean sine wave from such an oscillator, add a
small resistor (or small L, or large C, whatever is convenient) in series
with the crystal and amplify as needed.

BFO harmonics can be a problem in multiband receivers. It may be
easier to avoid generating them than to remove them afterward by
filtering.

73, ian K3IMW

On Sun, Mar 11, 2018 at 12:33 PM, Whitebear1122 <whitebear1122 at comcast.net>
wrote:

> Thanks Darrell for the information.  I double checked the wiring at it’s
> good, the BFO runs at 100 KC fine.  The output is not symmetrical but is
> not horrible.  Then the BFO is up and running as designed.
>
> 73, Scott WA9WFA
>
> > On Mar 11, 2018, at 2:11 PM, WA5VGO <hbrnut at suddenlink.net> wrote:
> >
> > Most of the BFO’s I’ve looked at on a scope are not perfect sine waves.
> At the very least they are asymmetrical and at the worst they have spikes
> or have squared off edges. I spite of their less than perfect appearance,
> they all seemed to work fine.
> >
> > 73,
> > Darrell
>
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