LF: Re: QRM - Other

["Alan Melia" <alan.melia@btinternet.com>]

What is worse Jim is there is no credible scientific study published on whether the work and how. For those with the ''right'' kinf of mind it can be an amusing exercise to take this up with the makers. Oh on the ones we looked at the chip (filed top) was a 555 or 556 timer. One maker quoted a University report. When chased it was not done by a science faculty and was never published. It gets boring when the best  justification is '' We've sold thousands so it must work''

 

Alan

G3NYK 

----- Original Message -----

From: hvanesce@comcast.net

To: rsgb_lf_group@blacksheep.org

Sent: Thursday, February 14, 2019 8:50 PM

Subject: LF: QRM - Other

 

This popular item doesn?t seem particularly friendly for ULF-VLF; 40 to 76 turns wrapped around the home?s water main pipe, ~ 2 amps out, sweeping 1 kHz to 20 kHz every 50 milliseconds.

https://www.scaleblaster.com/wp-content/uploads/docs/spec-max.pdf

https://www.scaleblaster.com/wp-content/uploads/docs/installation-max.pdf

which would seem to give roughly 40 fT at 100m at for the specified 70 turns on 4 cm water main, not counting eddy currents in the copper pipe.

Not sure how current varies* with frequency in these devices, or how rectangular the current waveform is.

  * (guessing current varies as 1/f, which would mean roughly 30 fT at 50m at 10 kHz)

 

A commercial unit provides 10A-40A into a 200uH coil around the water main (less current into the nominal 1 mH coil):

https://www.scaleblaster.com/wp-content/uploads/2016/08/SB-4000-clm276.pdf

https://www.scaleblaster.com/wp-content/uploads/2016/07/Sb1200-SB4000-Install-Operations-Manual.pdf

which would seem to give roughly 10 fT at 1 km for the specified 7 turns on 106 cm water main.

 

- Jim AA5BW