I've got a Sangean 505 SW receiver and decided to put up a long wire
antenna outside between a tree and the house. The reception using the
device is pretty amazing. I'm based in Sydney Australia and I can pick
up BBC, VOA, CBC Radio Netherlands. The annoying thing is that there
is periodic interference, 30 seconds of bad static that washes out the
signal completely followed by 65 seconds of clear signal, 30 seconds
of static, etc, etc. The interference does not seem to change night or
day. I'm thinking some type of electrical interference perhaps from
the house or something generating the noise outside the house that the
antenna is picking up.

If I use the telescoping antenna built-into the radio, no such
interference existing, or I could not hear it.

Any ideas on fixing it?