BELKIN was founded in southern California in 1983 by Chet Pipkin in his parent's garage. A great personal story as today Belkin is now a worldwide company and owns both Cisco and Linksys. In the early 2000s they released conditioners for the consumer AV market. These were stylish units with the Belkin stamp of quality and filled a necessary home theater niche. Models were the PF-30, 40, and 60. In a mysterious move around 2010 Bekin decided to discontinue the entire line, much to the disappointment of the AV community. It was a shame because these were affordable quality units with unique styling and elegant displays instead of the rough industrial look of other brands. A competitor Monster Cable made sylish unit that were well regarded but were also discontinued around the same time.
In 2006 I bought a new silver PF30 (AP20800-10) and a black (AP20800-08). The earlier version is dated 11/2002 and the black one 5/2005. The earlier model has PUREAV stamped in the top cover and on the front which gives it a high-tech look. The later version chnaged to a plain "Belkin" label and plain black cover. Were there other changes? See below.
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STAGE 1 FILTER
First its important to understand the Stage 1 filter which has been around for decades and is used extensively worldwide. The purpose of a high-current Stage 1 filter is to block EMI/RFI above 60Hz. EMI noise ranges are 150 kHz and 30 MHz and in some cases begins as low as 10 kHz. The issue is that only so much filtering can be added without causing insertion loss and distorting the 60HZ sine wave. There are more exotic levels of filtering but those are not typically found in this type of equipment.
- Special "X" and "Y" type capacitors are used. One X cap goes between the rails (called Differential mode) while two Y caps go from rail to ground (called Common mode). An X type burns through (open) when blown while the Y keeps drawing current when blown to maintain grounding. These caps filter out EMI/RFI.
- Toroidal chokes and wire-wound coils are used inline with each rail to filter out high frequencies.
- A MOV is typically used on each rail at the output. These increase resistance as voltage rises and clamp down on spikes.
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BELOW:This unit has four coaxial jacks for cable/satellite in addition to ethernet and telephone line protection. The black unit has no ethernet/phone feature and only two coaxial jacks. The black unit has red LEDs on the 'always on' outlets.
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BELOW: The silver PF30 layout is clean and functional. It appears to use Stage 1 filters without Y caps. Note the fuses on the upper left which are the protection for the ethernet lines. The section on on the upper left of the large board are for the high current outlet. The two choke/cap paths on the far right filter the video AC outlets.
The small silver components between the orange MOVs are thermal fuses.
Belkin promotes its "Purefilter" circuit as a key feature and puts a
light on the front panel to show the function working. The manual says "The multiphase PureFilter Circuitry provides true isolation
between audio, video, and high-current components". Euphemisms aside its simply a name given to the three individual filter banks. The manual says there is overvoltage protection that disconnects and reconnects when necessary. I suspect that is the function of the IC chip as the two black relays are the only other active devices.
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BELOW:The black PF30 has more parts on the board despite no ethernet and RJ45 protection the black . This includes a larger PIC16F flash microprocessor and three 5W power resistors to replace the 2W versions used on the earlier model. Carli capacitors are the same but the MOVS and thermal fuses are different brands. The board is stamped PF-30D_V1.2 while the older model has no version number.
I noticed something odd however. With the top open and the unit switched off the three white power resistors in the center were very warm. The audio outlets on the back are listed as "always on" but heat coming off worried me the unit was wasting power even when off. So I ran a meter on the unit and the current draw calculated out to only $.17 a year.
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CONCLUSION
So do line conditioners serve a purpose? Absolutely!
The amount of EMI/RFI on modern power grids is significant. Allowing it to pass into expensive TVs and AV systems is very risky and irresponsible to ignore in my opinion.
Creating a safe harbor for your equipment should be a priority. However, marketing AV filters to the general public is tricky. Despite the filters' effectiveness in many cases they don't produce an audible result. The result is that the mainstream scoffed at their effectiveness while some considered them worthless. I find this humourous considering how much people spend on AV products with little or no benefit yet find it hard to believe that filtering EMI/RFI is a good thing.
So what should a line conditioner contain? In my opinion a transformer to stabilize the voltage, individual stage 1 or better filters for each outlet and overvoltage monitoring. It should also be stylish with few lights to integrate with home theater equipment and not have an industrial or "band" look. A tall order? Belkin and Monster managed this in the 2000s without much fuss.
COMMENT: One criticism is when companies use names like "power technology, pure filtering, etc, etc" to describe their filter circuits inside. Because of UL regulations a company can't deviate much from using Stage 1 filters which means that most line conditioners are pretty much the same inside, boring. So in advertising surge suppressor companies tended to give cute names to their audio circuits rather than explain them in detail. This is wrong because people who understand electronics concepts are likely to buy quality surge supressors units. So instead of dumbing down the concepts why not openly state the components used inside and explain the schematic in use? This is the only way for the informed consumer to compare products and their effectiveness.
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