HF High Power Impedance Transformers

Does the operation of a treadmill or your exercise equipment wipe out your radio receiver reception? We have heard cases where the treadmill from a neighbor’s house wiped out the ham radio receiver reception from 2-30 Mhz! The treadmill source was finally isolated to a variable speed motor power supply that was injecting RFI into the AC wiring of the house and the AC wiring was acting as a transmitting antenna broadcasting the signal to the entire neighborhood. The case was difficult to track down since the broadband RFI interference only occurred at 7-8 pm each nite when the neighbor used the treadmill. As with all RFI cases the sequence is similar: Find the Source, Choke the Path, Protect the Victim.

Once the source was identified, a simple solution was to choke off the transmitting antenna with a AC line choke shown below which eliminated the interference problem to the ham receiver:

Testimonials

F400-31 AC Power Cord Choke completely cured the RFI problem I had with my wife’s treadmill. Now I can hear the weak signals!

73,
Jim K4AXF
Icom IC-725
Grottoes, Shenandoah Valley, Virginia
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The high power ferrite impedance transformer series (> 1:1), configured with outputs to act as a baluns (unbalanced coax in to balanced load output) or as ununs (unbalanced coax input to unbalanced load output) are designed for demanding radio transmitter stations that run over 1,000 watts PEP or run continuous modes like AM, digital, RTTY, FM, etc. at high power levels. Radio contest operators, commercial shortwave broadcast, and industrial and commercial stations use these transformers for for a variety of balanced and unbalanced antenna loads.  Baluns are typically used for balanced loads and antennas like dipoles, loops, log periodics, and direct feed yagi/beams.  Ununs are used  with verticals, end fed wires, horizontal dipoles, G5RV/ZS6BKW, Zepps, vertical wire beams, etc).  All products are in an enclosed NEMA water resistant box with SO-239 input connector and stainless steel side/top studs with wing nuts or side and top eyebolts.  The enclosure box has mounting “side feet” for attachment to a post or antenna boom using nylon ties.