Th CU-1-5000LF unun is useful as common mode feed line chokes or coax to antenna interfaces. SO-239 output models can also be used with balanced antennas if a short coax cable “pigtail” is used on the output and connected to the antenna. Rated 5000 Watts PEP from .2-5 Mhz. Use as line isolator, antenna interface, or as a common mode choke to keep RF on the antenna and off the outside of the coax braid. These high powered chokes are more effective then our sleeve feed line chokes due to multi-turn ferrite bead topology using high permeability ferrite cores which provides a higher choking impedance over a broad frequency range. Typical common mode rejection (CMRR) is 30-42 over the frequency range (see graph) For most effective results, use 1 choke at the antenna feed point to keep transmit RF off the coax braidand another at the radio end of the coax. Helps reduce noise floor too by choking off common mode neighborhood noise picked up on outside of coax braid. Available in 1.5K and 5K PEP models. Picture shows 1.5KW model, but 5KW model is same size and frequency specs but 5KW PEP.
5000 Watt Rated 1:1 CUBE™ Choke - .2-5 MHz (effective to 100 KHz)
Iron powder cores are more stable than ferrites and do not saturate as easily so they are best for tuned circuits, filters, and high power inductors. They come in different “Mixes” for use at different frequencies. For best “Q” use the Mix specified for your frequency.To find the number of turns to give the desired inductance for your coil use the formula below:
Turns = 100 x 
Toroid Dimensions
To order specify core size and mix (e.g. T200A-2). Available in sizes that have µH per 100 turns shown in table.
All iron powder cores are special orders. Please allow one week for shipment after order received.
The iron powder cores shown in the above tables are primarily used for either high power feed line chokes for common mode current reduction or for 4:1 and 9;1 very high power transmission line transformers.
For high power feed line chokes, choose the inside diameter of the iron powder core closest to the transmission line outside diameter and use 6-20 cores at the junction with the antenna feed.
For 4:1 (50/200 or 75/300 ohm) transmission line transformers in the range of 1.8-30 Mhz, select the size appropriate for the power level as follows:
T200A x 2 = 1.5KW
T300A x 2 = 2.5KW
T400A x 2 = 5KW
Use Mix 2 for all the above transmission line transformers. Fully assembled and enclosed units are available for each of the power levels. Click HERE for information.
4:1 transmission line transformers using iron powder cores are typically used for ladder line to 50 ohm coax connections
For .1 – 2 Mhz wide band transformers use Mix 26 which has a higher permeability and requires less turns to achieve a given inductance. Mix 2 has almost constant permeability from 1-30 Mhz. Mix 26 has an initial permeability of 75 at .1 Mhz and gradually decreases to about 10 at 30 Mhz. For high power AM broadcast range (.5-1.7 Mhz) transformer, use Mix 26 to reduce the turn count.
Minimum order for iron powder cores is $50
Shipping on larger cores in quantity may be more than $10 – email/call for quote.