Walter G3JKV said:.

FWIW, we had most problems with Decca skywave interference at sunspot

minimum.

There is this thing called LUF (Lowest Usable Frequency). Not much in ham
literature about it but from Bill Orr's Radio Handbook it depends on
transmitter erp and atmospheric noise. Generally speaking the LUF can be
lowered (at HF) by approximately 2MHz for each 10dB increase in erp.
However it is obvious that the LUF changes throughout the day. Does it
follow the MUF? If it does then it will follow the sunspot cycle.
Are there any average graphs of LUF?
I understand that most data available is for commercial link reliability and
ignores the esoteric magnetic effects that we have been using on LF.
Regards,
Peter, G3LDO

e-mail <[email protected]>

Web <http://web.ukonline.co.uk/g3ldo>