[Lowfer] Mystery signal on 137.000

[N1BUG]

For several hours there has been a very strong carrier on 137.000
kHz. I have seen this before but only for an hour or two at a time.
It has been there today for at least 8 hours, maybe longer as I
don't know when it started. I'm not sure if this could be CFH
testing, or ???

During the day this signal is very consistent within +/- 0.5 dB at
my station.

73,
Paul N1BUG