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Help! 80m - Every 65 kHz - Cycles Every 60 Seconds

Jan 20th 2022, 11:20


Joined: May 27th 2020, 20:19
Total Topics: 0
Total Posts: 0
Please, can anyone help? A couple weeks ago, HF RFI appeared that is audible and visible on my monitor. It presents as follows. (1) It raises the noise floor with hash on all HF bands. (2) On 80m, it is the worse! (80m antenna is dipole fed with LMR 400). Noise floor is now S-9, but every 65 kHz there is a S-9+15db noise; it is constant, but cycles on/off every 60 seconds (the rise and fall of this particular, wide spike, takes less than 1 second). (3) On 10m-20m, noise floor is S-6, but when I beam between 300-360 degrees, it rises to S-8. So, it would appear I may have the general direction, perhaps 330 degrees.

Using a small AM radio, I have swept my house. I can't detect anything that would cause this. My neighbor has an HVAC unit that is in the direction of around 330 degrees (but AM radio doesn't denote strong RFI from the unit); he is willing to turn off his unit for a couple minutes, so I can see if his HVAC is the cause. I am waiting on him to have an opportunity to help me test this.

Does anyone have any ideas or thoughts, any experiences with RFI that cycles on/off every 60 seconds and takes place every 65 kHz? Does anyone have recommendations for an RFI detector that won't break the bank?

Huge Thanks & 73,
David WR4N
Jan 20th 2022, 12:24


Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
This is Part One of a multi part article dealing with setting up a SDR as a RFI site survey tool to assist in RFI detection, location, and mitigation. Further, part one will set the stage for how captures of the RFI were accomplished, and visualized.

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