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Array Solutions

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W3NQN AC Line Filter AC-7










The NQN 7-amp AC line filter was developed for high-level RF interference environments, where computer and monitor power-line noise causes a problem with sensitive receivers, as well as with critical listening and recording environments such as high-end audio studios, home theaters, and audiophile stereo systems.

The NQN AC line filter is especially effective in eliminating the high-level AC line noise generated by the six or more computer/monitor systems used by amateur radio operators during multi-multi contesting. Also noise sources such as wall-wart generated RFI is a serious station problem.  To address this issue the AC-7 can be supplied with an optional IEC-to-NEMA adapter so wall-warts and other equipment may be plugged into it.  See Price list to purchase this option.

The NQN AC line filter features the following:

  1. Line cord radiation is minimized by using a three-wire power line cord having a foil shield and a drain wire.
  2. Nine (9) capacitors are used  and are all AC-rated Class Y2 or Class X2.
  3. Four 52 uH Powdered iron toroidal cores (two per line) provide optimum power-line differential-mode filtering and are rated for a maximum line current of 7 amperes.
  4. The foil shields and third-wire ground are maintained via the filter's aluminum case from the IEC female receptacle to the NEMA three-prong male AC plug.
  5. The 115-VAC leakage current measured through a 1,500 ohm resistor from the filter case to ground is less than 1.4 milli-ampere.
  6. The voltage drop between the filter input and output at a load current of seven amperes is about 1 volt which is less than a 1% drop in the 115-VAC input line voltage.
  7. A three-prong female-to-two-prong-male adapter "cheater" is included (with the AC-7 model only) if you need to break the shield ground at your 115 VAC power receptacle to eliminate a ground loop via the shield.
  8. The cover is secured to the aluminum case with four 6-32 machine screws into four 6-32 threaded holes in the cover that are provided by the manufacturer.













W3NQN AC Line filter - inside view.

Compare this with a Brand "C" filter which only handles common-mode interference problems.  The NQN AC power-line filters are optimized for common-mode and differential-mode filtering and have about 3 times the components of brand "C".  Plus they are all rated for this type of duty.  If you compare the size of cores and windings of other filters we think you will agree the NQN AC-7 power-line filters are of the highest quality.  

Engineering that makes a difference in the station.  

Several progressive contest stations have already converted to the NQN AC power-line filters to eliminate the computer generated noise.  Shouldn't you?  If you have my SixPak which can isolate down to 85 db between stations, you will benefit from getting rid of the PC and monitor trash.  The next thing you need to do is replace all your RF cables with double shielded RG142 to achieve that next level of receiver "quietness".

Helpful for reducing background noise in your high-end audio system too.

According to Audio Expert Jim Smith,  

"Your system will love it".

(Click the image above to visit Jim's site)

February 2, 2012: Thanks to Jim Smith for recommending the AC7 Line Filter in his "Quarter Notes" newsletter. The demand for these filters from audiophiles is greatly appreciated, but as these filters are each custom-made with hand-craftsmanship by Ed Wetherhold (the designer) himself, it may take a few weeks to catch up with the order volume. We thank you and request that you would be patient while your filter is built. - Array Solutions

Q: You have 4 different versions available, which model should I purchase?

A1: If you're outside the United States and will be filtering 200v to 220v or so, the AC7-EU is for you. This filter has standard IEC connectors on it for both input and output.

A2: If you're elsewhere, the decision comes down to whether or not your equipment has an IEC connector on it, and if you want to replace the power cord totally or place the filter at the equipment end of the power cord or at the wall outlet end. The standard AC-7 (pictured above) is designed to replace the entire power cord for your equipment that uses an IEC connector.

A3: The AC-7B (shown here) is intended to install at the equipment end of your power cord and has male and female IEC connectors/

AC-7B with short "pigtail" IEC cords  These are the IEC connectors on the AC-7B

A4: The AC-7A is similar to the AC-7B with short pigtail leads but having a "normal" (NEMA 5-15P) plug for your wall outlet and a similar "normal" socket (NEMA 5-15R).

The AC-7A is outfitted with these connectors and would install at the wall outlet end of your existing power cord.

At present, we do not offer filters with other connectors - e.g.; C5, C7.

 Pricing and Ordering