[TowerTalk] source of interference

[John Keating]

Wondering if anyone can suggest what might cause this interference: It is broadband, occurring across the HF spectrum every 8Khz, and is "on" for about two minutes, then "off" for about two minutes, 24/7. It raises my noise floor by about 10dB.

It is not coming from my QTH, as I have killed all the power, run the radio and panadapter from battery, and it is still there. Because I am using a temporary vertical antenna, I can't pin down the direction of the source.

John
K7LY