Model BA-1-1500 is a 1:1 balun kit used to translate a 50 ohm unbalanced input to 50 ohms unbalanced at power levels up to 1500 watts PEP when used with a matched load. With a matched load the SWR will not exceed 1.5 over the frequency range 1.8 to 30 MHz. 1,500 PEP watt rating on a 25% duty cycle. The kit consists of a F240 ferrite core, two colors of selected insulated wire, two SO-239 connectors (one for input and one for output connections) with stainless steel hardware, and an illustrated instruction manual with directions to assemble the kit as a 1 to 1 balun (unbalanced coax to balanced antenna/load) or unun (unbalanced to unbalanced). Leave one of the SO-239 connectors off on the output side and connect to your balanced antenna (dipole, beam driven elements, etc). To use as a line isolator/common mode choke, use both SO-239 connectors and insert in series with the coax feed line. For best results use one at the antenna and one for the rig side at the antenna tuner. The number of turns on the toroid can be changed to emphasize the low, mid or high portion of the 160-10 meter bands range as well as the choking impedance (see graph below). Assembly time is about 30 minutes. You can vary the number of turns to emphasize different frequency ranges. BA-1-1500 Choking Z magnitude – 14 Turns and 10 Turns Just add your custom enclosure, or optional enclosure box below, with the kit and you have a compete 1:1 current balun/unun.
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.