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Gday Dennis
Re the Kendricks, i have seen the blurb, but havent seen a real unit yet
It states it uses PWM, and even if the unit itself is well shielded ( what i suspect they mean ), the cables going from it to the heater element, and the heater element itself can all act as radiators.
I have designed several PWM dewheaters ( passive and microprocessor controlled ). The units will run with pretty much no RFI when a load is close coupled. ( Ie a few inches max )
Put a lead from the controller to the heater element, ( and throw in 900mm of nichrome wire ) and it becomes a really nice RFI radiator.
Also, i dont know if the Kendricks switch on the high side or the low side.
Most use lowside switching, which means it is the earth return that is pulsing.
Hence to shield this setup, you need as a minimum, a three conductor connector. They only use RCAs so i doubt they are RFI free, when connected to an unshielded heater.
Need to get one to play with :-)
Gday Karl
All my cheapo plugpacks are unearthed.
However, i nearly always run my ETX off a battery, and to get constant supply, I have also have built a switchmode DC-DC boost convertor.
I can filter the output through an LC filter followed by a toroid with both lines wound "counter" to get rid of most of the common mode bits.
Its not perfect, but better than a cheap plugpack
Andrew
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