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 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.
Loop Antennas
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.