5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms Six Cores

High-power 5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms, with six cores, converts a 50Ω unbalanced transmission line (coaxial cable) to a 25Ω balanced feedpoint for low-impedance antennas like OptiBeam or SteppIR.

Three separate cores are intended for the balun with high common-mode impedance, and three cores are intended for impedance transformation, enabling low-loss matching to standard 50Ω coaxial cable.

By separating the balun and impedance transformer functions, the characteristics of both were significantly improved, preventing mutual coupling and poor performance.

Teflon-insulated AWG 10 wires were used to wind the impedance transformer, enabling high currents during impedance transformation without overheating.

High common-mode impedance, low standing wave ratio (SWR), and extreme power ratings are the main features. This balun can easily handle any linear amplifier, including the FU728F, GU84, GS35B, MRF1K5, BLF188, ART1K6, ART1K9, and ART2K5.

 

Key Features:

• For low-impedance antennas designed with a 25Ω feed point.
• Extreme power handling. Up to 5000W on low SWR antennas.
• Wideband operation: From 7 MHz to 51 MHz.
• High common-mode impedance across the whole frequency range.
• Very low SWR on a 25Ω load.
• Does not need a tuner for operation at any frequency
• Cores of the highest quality were used to construct the balun and impedance transformer.
• High-temperature AWG 10 Teflon wires were used for the impedance transformer to ensure safe operation.
• SO239 input connector (by order 7/16 DIN).

 

5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms Six Cores Appearance:

 

5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms ordering option:

• SKU: 2989 5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms SO239 input connector (this one)
• SKU: 2990 5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms 7/16 DIN input connector (+25 EUR)
• By order with Wing Nuts instead of Plain Brass Hex Nuts (no price change)

 

5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms Six Cores side view:

Measured common-mode impedance of 5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms

• 7.1MHz 580Ω
• 10MHz 1kΩ
• 14MHz 2kΩ
• 21MHz 5kΩ
• 24.9MHz 3.1kΩ
• 28MHz 2kΩ
• 50MHz 650Ω
• 54MHz 580Ω

 

Maximum power input at SWR:

1:1 = 5000 W; 1:1.5 = 3350 W; 1:2 = 2500 W; 1:3 = 1650 W

 

Mechanical data:

Dimensions: L x W x H: 200 x 120 x 90mm without terminals.
Weight 1.3kg

 

Maximum SWR on a 25Ω load:

• 3.5MHz 1.2
• 7MHz 1.14
• 14.1MHz 1.1
• 21.2MHz 1.06
• 28MHz 1.07
• 50MHz 1.15

 

5000W Balun and 1-2 Impedance Transformer 25 to 50 ohms inside view:

 

Customer questions:

Q1: I bought a BALUN 1:2 25 – 50 Ohm rated for 3kW, which heats up significantly during RTTY operation at 1kW power. Why?
A: Thin wire, thin coaxial cable, and inadequate ferrites were used. This is why the balun overheats. If you don’t burn it today, it will happen tomorrow.

Q2: But the Balun is rated for 3kW in CW and 6kW in SSB; it overheats at just 1kW in RTTY mode. Why is that?
A: Please review the first answer again.

Q3: I came across a picture online of a ferrite-wound wire that the manufacturer labels as a 25:50 Ohm balun. I’m wondering if it’s truly a balun, an impedance transformer, or both?

A: If the device has a single-wound wire designed to transform the impedance from 25 ohms to 50 ohms, then it functions solely as an impedance transformer. There is no balun inside, no matter what the manufacturer claims.

Q4: I found pictures of the manufacturer online that show both the balun and the impedance transformer wound on a single ferrite core. Is that okay?
A: Using shortcuts to save money while compromising on quality is a clear warning sign to avoid purchasing from such manufacturers. While you may pay less upfront, you might end up with 20% fewer contacts in the contests due to poor balun performance and increased SWR. If that doesn’t concern you, then that’s fine.

Q5: Some antenna manufacturers claim that their antenna does not need a balun or “works very well without a balun“. Is it true?
A: If they can prove the non-existence of common-mode currents, that would be fine. However, this is impossible to confirm on any HF or VHF antenna.

Q6: Which antennas need a balun?
A: All dipoles, all Yagis, Quad antennas, and Vertical (GP) antennas. No exception.

Q7: But almost all Quad antenna producers claim that a Quad antenna does not need a balun. Is it true?1
A: Please read Q5 and Q6.

Q8: But I have a perfect 1:1 SWR on the antenna without a balun? Is it good?
A: YT1NT Quote: Without a balun, some of the transmitter power is lost. The resonance of the antenna is masked and distorted; what is actually measured is the resonance of the entire system, in which the shield of the coaxial cable functions as part of the antenna. The resonance of that system does not have to have anything to do with the resonance of the antenna itself; i.e., the fact that we set the resonance of the system does not mean that the antenna is anywhere close to resonance, which can cause significant losses. This will lead to a weaker signal and a worse ranking in competitions.

Q9: I purchased a balun from a ham radio vendor, but it didn’t come with any common-mode impedance data. Is the balun good?
A: It could be, but that’s not guaranteed. The fact that the balun is available for purchase doesn’t necessarily mean it’s good. What truly matters is whether the common-mode impedance data has been measured at the frequencies of your interest. If you don’t have that information, you may have a problem. Or it might be unclear what you’ve actually bought.

 

The other Common-Mode Chokes – baluns and impedance transformers are here.