[Lowfer] Spectran Question

[Alan Melia]

Peter it isn't sufficient to just do summs and diffs on the declared
frequencies you also need to conside a 2nd harmonic folding back round the
sampling frequency. I would say you are definitely overloading the sound
card. If you are using a laptop and the "mic" input there may be AGC on that
input which does not help.

You must bear in mind that the sound card has a very large dynamic range but
you need to set the input level so low you will not be able to hear the
signals in the speakers to make best use of this. Ideally the noise should
be set to about  -100dB. There may also be signals outside the Spectran
range....maybe a local NDB of a local MW BC station. In which case there may
be some contribution from the receiver. Most amateur receivers do not
perform terribly well on LF frequencies, many have attenuation to reduce the
IMDs from strong BC stations.

If it is and intermod product there is a check you can do. Reduce the
level...the product should fade more rapidly than the real components.

Cheers de Alan G3NYK