[GreenKeys] OT QRM source

[amourdutigre]

I normally do not post off topic things, but this was too good not to.

I have a strange work schedule. I both teach English to non-speakers of English (adults) and I do research. My research schedule is on the weekends, overnights. I have been on family leave act leave to take care of my wife, and as a result of her recovery I have been doing the daily things that she would normally do such as laundry etc.

That said, this means that at night, after she went to bed, I would listen to HF world band (what is left of it) or amateur HF. However, there was an ongoing and terrible QRM that ruined the entire upper two thirds of the HF spectrum, and even mildly effected the lo bands.

It sounded like a VERY broad band data transmission. First, I made sure it was not my elderly Icom R-70. The same interference showed up on my IC-730, and my Heath receivers. This interference seemed random. Fifteen seconds of 'data', then off. Did this for twenty minutes or so, then turned to a 'jet engine spooling up' type sound that was deafening. Then back to the data sound. Then finally, after an hour and six minutes, it stopped. (The reason for this will be obvious in a minute.)

I had dark conspiratorial thoughts that some alphabet agency was sending covert instructions to their minions in some hell hole of the world. I was on the verge of borrowing a buddy's spectrum analyzer and attempting to see what this 'data' looked like.

Well, I got up from my radios in my QTH (which is in the finished garage across from the washer and dryer), got another diet Dr. Pepper from the fridge under my radio bench, and put another load of laundry in the washer. 

Sat back down at the radio, and I will be darned the QRM is back. On again, off again. Data. Buzz sounds. Jet engines winding up.

I leaned back in my chair, Dr. Pepper in hand, contemplating a letter to the FCC, when I started watching the washer machine. It is a new Maytag high efficiency front loading unit. Data noise starts. Drum of washer starts. Data noise stops, Drum of washer stops. Data noise, drum reverses. Jet engine noises, drum spools up to speed. Laundry is finished, QRM is gone.

The washer was making the QRM! There is a computer in there, and what is worse, the motor speed is controlled by pulse modulated DC. Very noisy. I never even suspected this!

To attempt to solve this, I grounded the washer to a separate earth ground. This helped. Then I wound the power cord around a toroid, which helped some more. At least 6 dB down. Still not enough. However, these new laundry machines are made in part out of plastic, so the long and the short of it is, when I want to listen or operate on HF, I will not do laundry unless I figure out how to kill the rest of the QRM. If copper screen wire was not so expensive, I would build a Faraday cage for the darned thing (not really, my wife who is very understanding of my radio habit probably would draw the line at that...) More practically, I am considering calling Maytag and inquiring about noise filters for their machines.

Sorry for the lengthy post, it was sorta funny how I discovered the source of the 'covert' digital comms!

Best and 73

Joe Herdler
KB0TXC
Greenkeys
TCI
/NNNN