Purpose. Model BA-4-1500DC is a 4:1 dual core balun kit (assembly required from parts supplied) used to translate a 50 ohm input up to 200 ohms at RF power levels up to 1000 watts when used with a matched load. It provides conversion from unbalanced coax to balanced ladder line/antenna feed point and gives a 4:1 impedance step-up to reduce SWR on the coax. Place at the junction of the balanced line and the coax to convert from balanced line to unbalanced coax.
KIT Contents. The kit consists of a 2 ferrite toroidal cores, two colors of insulated wire, a SO-239 UHF connector with stainless steel hardware, and an instruction manual.
Assembly time: About 1 hour, illustrated manual included with purchase.
Radio Club idea:
Buy 10 for a club do it yourself construction project - you can learn something and also build an end fed antenna (just add wire).
Product picture shows assembled item of all components in kit.
NOTE: for higher power and a true current balanced 4:1, use our BA-4-1500DC dual core 4;1 balun kit
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.
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