Description
CMF-250B: The Diamond CMF-250B is a common mode filter designed to effectively reduce unwanted RF currents on coaxial cables in HF and 6 meter installations. In the presence of unbalanced antenna systems, non-optimal feed paths or insufficient RF suppression, common-mode currents can compromise tuning stability, radiation quality and the electromagnetic compatibility of the station environment. The CMF-250B addresses these issues directly by acting on the external conductor of the coaxial cable, where these currents originate. Unlike conventional low-pass filters, which operate predominantly on harmonics, the CMF-250B provides more than 30 dB of common-mode attenuation, reliably reducing stray currents and improving the overall behavior of the antenna system.
Construction and installation:
The compact and robust construction, with a length of approximately 190 mm and a weight of approximately 300 g, allows for easy integration into any 50 Ohm coaxial line.
The SO-239 connectors ensure immediate compatibility with most existing systems.
It is connected between the radio and the antenna
The Diamond CMF-250B is particularly indicated when the following occur:
RF returns to station
Interference on radio, audio or TV equipment
Instability in antenna tuning
Anomalous behavior of the radiant system
Specifications:
Frequency: 1-54MHz
Maximum Power Rating: 250W PEP (1-30 MHz) 200W PEP (30-54 MHz)
Common mode attenuation: More than 30 dB
Insertion Loss: Less than 1.2
Impedance: 50 Ohms
Connector: M-J (SO-239)
Length: 190mm (Including connector part)
Weight: Approximately 300g
