These baluns and ununs can be used for impedance matching and also as End Fed halfwave antenna matching transformers to 50 or 75 ohm coax cable.
FT400-3I, ID=3", RFI Range 1-300 MHz, Case of 25
Product Details
RFI Range (MHz): 1-300 MHz
ID-B (in/mm): 3/76.2
OD-A (in/mm): 4/101.6
Height-C (in/mm): 1/25.4
Weight (oz/gm): 420
Initial permeability: 1500
(4″ OD, 3″ ID hole), available in mix 31 only, Case of 25
Excellent for large cables or multiple cables – use multiple cores for higher choking. Also useful when you need high turns count for high choking with large cable - works on AC or DC power lines and also coax cable lines.