EMI Filters and RF Shielding Products

Here you will find frequently asked questions (FAQ) and troubleshooting suggestions for our ACTIV EMI Filters (as well as FOIL Filters which are no longer in production). Our filters are designed to work seamlessly and invisibly when installed correctly. However, occasionally there is a communication problem or network/software hiccup that interferes with proper functioning. And less frequently, there is a hardware failure. In the event you have a problem or question about your FOIL filter, the answer may be here or you can always contact us directly for assistance.

Ethernet EMI Filters

This section covers all ACTIV Ethernet Filters and FOIL Ethernet Filters (no longer in production):

ACTIV 10G (and 10G-HW)
ACTIV POE (and POE-HW)
FOIL 10/100v3 (no longer in production)
GigaFOILv3 and v4 (no longer in production)
GigaFOILv4-PLENUM (no longer in production)
GigaFOILv4-POE (no longer in production)

My filter doesn't work. What should I do?

In the event that your Ethernet EMI filter fails to work or stops working, follow these instructions:

NOTE: ACTIV and FOIL Ethernet filters pass Ethernet packets ONLY. They will NOT pass other signals such as the tones or pulses used by network cable testers or digital phone signals that are not based on Ethernet (TCP/IP). The ONLY way to test a FOIL Ethernet filter is to connect the filter to a computing device and a network (or other computing device) and verify connectivity.

Step 1. Verify the filter is plugged in and the power supply is functioning. ONLY USE THE POWER SUPPLY THAT WAS SHIPPED WITH THE FILTER. The power supply should be able to provide 5VDC and at least 2 amps to the filter. If necessary, use a multimeter to check that the power supply output is 5VDC or slightly higher.

Step 2. Check the input and output connectors and make sure the pins are not bent and are properly aligned so they will come in contact with the cable connector pins.

Step 3. Turn off the computing device, EMI filter and all network devices on that leg of the network. (The filter can be reset/turned off by unplugging the power supply.) Turn the devices back on, one at a time, starting from the network backbone down to the computing device. Allow ample time for each device to boot up individually and connect to the network.

Step 4. If there is still no connectivity, try "repairing" the network connection on the computing device or force the computing device to release its IP address and renegotiate with the network for a new IP address.

Step 5. Finally, verify that your computing device, cables and network are functioning properly by directly connecting the computing device to the network. You MUST use the same computing device, cables and network connection to positively remove these variables as possible causes of the problem. For the cables, you should either use an RJ-45 coupler to connect the cables together, or test each cable separately.

Step 6. If there is still no connectivity, then the filter may be faulty. It will be necessary for you to contact us and arrange for an RMA number.

All Ethernet EMI filters have a two year warranty from date of first sale.

Will your Ethernet EMI Filter work on CAT5e / CAT6 / etc.?

It depends. CAT5/CAT6/CAT7/etc. are cabling standards (ie wire gauge, twists per foot, insulation material, etc.). What matters is what is being transmitted over the cables. If it is Ethernet, then the Ethernet EMI filters will work. But CAT5/CAT6/CAT7/etc. are sometimes used to carry other things like proprietary data, power, thermostat signals, sound, etc. In those circumstances, the Ethernet EMI filters will not work and will actually block the signals.

I need an RJ-45 filter. Will your Ethernet EMI Filter work?

RJ-45 refers to the type of connector or jack (Registered Jack design #45). Just like the cabling question above, what matters is what is being transmitted through the connector/jack. If it is Ethernet, then the Ethernet EMI filters will work. But RJ-45 connectors/jacks are sometimes used to carry other things like proprietary data, power, thermostat signals, sound, etc. In those circumstances, the Ethernet EMI filters will not work and will block the signals.

I plugged my IP phone into your Ethernet EMI filter, but the phone won't work. Is the filter broken?

Ethernet based telephone systems (IP Phones) typically use Power Over Ethernet (POE) to power the phone. FOIL and ACTIV Ethernet filters (with the exception of our POE filters) do not pass power. To use your phone, you will need to use one of the following:

An AC adapter designed for use with your IP Phone. Usually IP phones have a DC jack just for this purpose. The downside is the adapter will be a significant source of RF emissions inside your enclosure/chamber.

A POE injector. These take the output from the filter and inject POE onto the cable which can then be plugged into the IP Phone. The downside is the injector will be a significant source of RF emissions inside your enclosure/chamber.

The ACTIV POE. This version of the ACTIV Ethernet filter has a POE injector built into the filter. The filter is designed with additional shielding and absorption to reduce the RF emissions radiated into your enclosure/chamber.

I'm using your Ethernet EMI filter on my enclosure/chamber and I'm seeing RF emissions radiating from the filter. Why is that?

Our Ethernet EMI filters use specialized circuit cards to bring the Ethernet signal into and out of the enclosure/chamber. This results in some RF emissions inside the enclosure/chamber.

Is the output cable shielded?

On FOIL Ethernet EMI filters, the output cable is NOT shielded. For ACTIV Ethernet EMI filters, the filter is shipped with an unshielded output cable, but a shielded output cable is available upon special request.

Does it matter if the body of the filter is inside or outside the enclosure/chamber?

The ACTIV Ethernet EMI filters are bidirectional. It does not matter if the body of the filter is inside or outside the enclosure.

USB EMI Filters

My USB EMI filter stopped working. How do I reset it?

If you encounter a problem with your USB EMI filter, try resetting it by disconnecting all USB cables and the DC power cable for a few minutes. Reconnect the DC power cable first, then the USB cable going to the host and then the USB cable going to the peripheral device. It is important to disconnect ALL cables and to reconnect in the order specified because the USB cables will power the filter circuit cards even when the DC power cable is disconnected and this may create an unstable situation and prevent the filter from truly resetting.

I'm using your USB EMI filter on my enclosure/chamber and I'm seeing RF emissions radiating from the filter. Why is that?

Our USB EMI filters use specialized circuit cards to bring the USB signal into and out of the enclosure/chamber. This results in some RF emissions inside the enclosure/chamber.

The voltage/current at the USB outputs is not what I was expecting. Why is that?

The ACTIV USB 3.1 EMI Filter uses the Power Delivery 3.0 specification including programmable power supply capability. The unit can negotiate sourced power at its Downstream Facing Port (DFP). The power profile is automatically negotiated over the DFP Type C interface to provide up to 60W (3A @ 20VDC) of filtered power.

The FOIL USB 2.0 follows the USB 2.0 standard which provides between 5.25 - 4.75 VDC and 500mA at the output. We target 5.1VDC, but the process of filtering the power (which is different from how we filter the data) creates a voltage drop that increases with current draw. Please note that the 500mA provided by USB 2.0 is often not sufficient to charge certain devices like phones or tablets. Those devices require the USB Battery Charging Specification which provides up to 1500mA.