25:1 to 81:1 Baluns/Ununs

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.

50:2450 ohm (49:1) CUBE™ Unun, 1.8-30 MHz for EFHW Antennas, 2000 Watts PEP

In stock
Product Details
MPN: CU-49-2000HF
Type: NEW
Input ohms/Output ohms: 50 in /2450 output
Frequency Range < 2:1 SWR (MHz): 1.8-30 MHz < 3:1 SWR
PEP Power Rating (watts): 2000
Insertion Loss (dB): <.05
Input Connector: SO239
Output Connector(s): top eyebolt, side stud for counterpoise
Transformer Topology: Triple Core Toroid
Hardware Type: Stainless Steel - 1/4"
Enclosure Size: 4" x 4" x 2" with side mounting tabs
Weight (pounds): 2
Antenna Compatability: End fed half wave

The CU-49-2000 is a 49 Unun housed in a NEMA enclosure box (4″ x 4″ x 2″) with top coax connector output of 2450 ohms used to translate a 50 Ω unbalanced coax input to 2450 Ω unbalanced output at RF power levels up to 2000 watts PEP. With a matched 2450 ohm load the SWR over the frequency range 1.8-30 MHz is less than 3:1 on the coax input terminal.

High power, triple core design for long life, side vents for air circulation..

The GROUND terminal is connected to the 50 Ω INPUT connector shield.

Input connector is a SO-239.

Also includes ground lug/wingnut connected to input shield connector.

This unun is DC grounded.

Just add half wave of antenna wire at lowest frequency desired and work the multiples of half wave above that frequency.

This product supercedes CU-49-2000LF

Application Note: When using the CU-40-2000HF with an antenna, you should measure the SWRs on the harmonic bands which the antenna is designed for (e.g. a 130 foot, 80 meter EFHW works on 80-40-20-10 if cut for the lower end of 80 meters, 3.5MHz). When used on non-harmonic related bands to the 3.5Mhz fundamental, the antenna must have a SWR (taken at the antenna feedpoint, not the end of the coax) < 1.5:1 without an antenna tuner, to be used at powers over 500 watts or any mode or with a 50% duty cycle.

There are many antenna configurations available on internet websites that say you can work non-harmonic bands with the use of an antenna tuner, but they forget to tell you that the unun will be over-taxed at low power levels since the impedance seen by the unun may not be close to 2450 ohms but may be very different.Using an antenna tuner only tunes the load seen at the antenna tuner end of the coax (e.g it only tunes the coax, not the antenna – the unun is still seeing an unmatched load and may easily saturate if too much power is fed to the unun). If the unun is used with an antenna tuner and an end fed wire antenna (130-135 feet in length), power should be reduced on those bands that show an SWR above 1.5:1 SWR, at the antenna feedpoint, without the tuner. If your antenna shows a SWR of 3:1 on any band, you should restrict the power level and/or duty cycle down to a level which doesn’t saturate the unun.The power input level will depend on band, mode and antenna design.

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