[TenTec] amp keying loop weirdness

[john, ke5c]

> High speed I/O devices are known to be affected by capacitive
loading.  Some drive long lines better than others.  The long cable
probably did it.  The short cable fixed it.  For those making your own
cables, pay attention to the "pf per ft" numbers.  Lower is better.
Usually this is a factor not considered to be a concern in audio
cables as most drivers are quite low Z devices.  On the other hand,
inputs with a high Z will experience HF roll-off with high capacity
type cables.

qsk lines are very low speed, and i would be more concerned that his
radio shack audio cable was poorly shielded and/or some multiple of a
1/4 wavelength of his operating frequency making it much more
susceptable to rf feedback. a good station grounding system would help
too.

73, john