[RFI] Pentair VS Pool Pump

James Jordan k4qpl2 at gmail.com
Thu Aug 23 16:34:39 EDT 2018

I started a string a couple of months ago asking about RFI with variable
speed drives like the Pentair pool pump for our rental property down at
VP5. Just got back and here's the report for what it's worth.
Bought one, had to remove the motor from the pump housing to get under the
airline weight limit and put the motor in a small carryon which weighed in
at 47 lbs. Check in clerk got a surprise when she lifted it over to the
conveyor! Next surprise must have been TSA as it had an "inspected" sticker
when it arrived. But all went well and it was an easy install. Didn't even
have to redo the plumbing as the drive bolts on to the existing housing
with four stainless steel bolts plus electricals.
I turned it on and found it was very quiet mechanically and giving great
circulation at about half speed of 1800 rpm and pulling <400 watts or maybe
30% of the power of the old motor. At $.44/Kwh that is a lot of dough over
time. Night time setting of 1000 rpm is about 175 watts. Amazing compared
to a conventional 1.5 HP motor running almost full time.
I next pulled out a nifty little AM-FM-SW transistor radio I've had for
years. YIKES!! That motor was putting out hash on all frequencies to the
point that almost nothing could be heard over it. Loudest near the motor,
but the RFI was being passed through the AC line all over the house. Turn
the motor off and all quiet again.
Fortunately I had anticipated this and also took with me a Schaffner power
line filter FN2070-12-06 that I bought from Mouser for about $42.00. I
removed the old mechanical timer from its box (no longer needed as the new
drive has built in timer/programming) and put the filter in its place. A
tight fit but it gave a weather proof enclosure and connection point
without any rewiring.
Presto! Turned the pump on and I had to stand right next to the drive to
get any RFI at all. Nothing in the house and the only RFI found was from a
few LED bulbs when putting the whip antenna of the radio right next to
I then went to the acid test with my K3 and various antennas/bands. Never
heard anything above the background noise level.
Guys, I don't get a commission, but if you (or your neighbors) have
anything using a variable speed drive that's creating RFI, the Schaffner
filter is a great value. Totally sealed in metal case and it just needs a
ground and the line goes through it in series.Note they have models for the
maximum current draw of the drive so choose accordingly. Mine is the 12 amp
version as that was a very conservative guess of max power in pool cleaning
speed of 3600 rpm. Mount as close to the drive as possible (mine was about
6 feet away on the wall next to the pump).
Next project will be to determine if it is possible to install solar
co-generating down there so that VP5M can continue as a viable DX
operation. I'm really nervous about that as the stakes are even bigger
economically. Cost of air conditioning, hot water, etc. are astronomical,
but on the other hand with about 25% of our rentals being
vacationing/contesting hams, (not counting me!) it is essential that the
property be free of RFI. Will be following the conversation to learn who to
avoid and whether it is even possible for solar and ham radio to be fully
Jim, K4QPL, VP5M

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