Wall Wart RFI Noise Filter

3417277681 - Wall Wart RFI Noise Filter
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Bullet 50:100 (2:1) HF Balun, .1-61 MHz, 500/1500 Watts PEP, Loop Antenna

Bullet-2B-500EB
$99.95
In stock
1
Product Details
MPN: Bullet-2B-500/Bullet-2B-1500
Country/Region of Manufacture: USA
Type: NEW
Input ohms/Output ohms: 50 in, 100 out
Frequency Range < 2:1 SWR (MHz): .1-61 MHz < 2 SWR
PEP Power Rating (watts): 500/1500
Input Connector: SO-239
Output Connector(s): Side Eyebolts
Hardware Type: Stainless Steel
Weight (pounds): 1
Antenna Compatability: Full Wave Loop

New improved version now goes down to 100 KHz and up to 61 MHz < 2:1 SWR!

The Bullet-2B is a multi-core balun with a compact enclosure (looks like a bullet) enclosure that is lightweight and easy to transport for your portable loop antenna solution. Halyard hoist at top of balun for convenient attachment point. Input is via SO-239 coax connector and output with side eye bolt output. Rated 500 Watts PEP Watts from .1-61 MHz. DC grounded to coax shield for static bleed off.

This transformer requires a feed line choke at the balun to isolate the coax feed line from the antenna. A coax noise filter is also recommended at the radio end of the coax..

Loop Antennas

Loop antennas are some of the best radiating and receiving antennas you can make. They can be in a triangle (called a delta loop), square or rectangle or even a circle. Horizontal loops can be fed anywhere that is convenient. Vertical delta loops(circumference length=1005/f(Mhz) are best fed 1/4 wavelength (length=246/f(Mhz)) from the top point down one side.

We offer pre-configured loop wire kits for your antenna building convenience. Just choose the band you need - see related products.

Want multiple bands from a loop antenna, consider the 4;1 Bullet (Bullet-4BEB in 500 or 1500 watts versions).

NOTE: We rate our Bullet baluns (and ununs) VERY conservatively at 500 watts PEP with a 50% duty cycle. Some manufacturers selling low cost baluns may use a 5% duty cycle for their PEP rating to make it appear you get a higher rated balun for a lower price, but you may in fact be getting be getting less. Their 1500 watts PEP really means 75 watts continuous or 150 watts at a 50% duty cycle compared to our 250 watts at 50% duty cycle. Our baluns typically cover a larger frequency range under 2:1 SWR which make your transceiver happy and probably will last longer with less electrical stress.

Remember we over engineer our products, to out perform our competition - just compare the weight of our baluns to theirs and you will know we put much more into our products so you don't have to worry about failure at a critical moment.


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Wall Wart switching DC power supplies that plug into the AC power line plug and provide DC power to laptops, routers, battery chargers, cell phone chargers, etc are a known source of broadband RFI (a.k.a dirty electricity) that effects many electrical devices including computers, radio receivers, HDTV systems, etc.  In many cases this extra RFI noise effects computer I/O speeds since they have to error correct the information packets many more times due to the noise interference causing packet errors.  A ferrite ring can often increase data throughput by reducing the error correction to normal rates.

A simple ferrite ring filter on the DC power line can help suppress the RFI noise affecting the victim device or keep the DC power cord from acting as an antenna and radiating RFI into other victim devices. This kit is also useful on laptop computer supplies, routers, cable modems, wireless phone charges, etc.

RFI WW Installation 300x288 - Wall Wart RFI Noise Filter

Installation is quick and easy: Just wrap the DC power cord through the center of the ring filter as many times as you can and reinstall.  For best results with long DC power lines, use one at the ring filter at the wall wart end (to prevent the wall wart power supply from using the DC line as an antenna) and another at the DC plug end (to prevent the electronics in the powered device from using the DC power cord as an antenna).  Typical installation is shown below:

The filter suppresses RFI in from .1-100 MHz.   Inside diameter is 3/4 inch/19 mm.

Since most households and office environments have multiple wall warts we offer the Wall Wart RFI Filter kit in bulk quantity packages.

Known RFI Generators include Roku/Sling-TV power adapter - Interference heard in the AM broadcast band
 and harmonics.
Also many ethernet Cable/DSL modems, cell phone chargers, computer power adapters have the same issue:
using the AC or DC side of the power supply as a radiating antenna.

RFI solution is to use a linear power supply, change adapters or wall wart ferrite filters