OCF dipole 3,5-28 MHz mk2

Product detailed description

OCF dipole 3.5-28 MHz.

New balun design 2025

- more massive boxes, thicker walls
- brass bushings for lid screws
- Uniform box design for all models
- new power limits
- wider choice of mechanical designs
- choice of pressure valve design
- choice of Amphenol N connector
- MINI version also available in clamp mount version
- overall precision design

Multiband dipole powered off-centre for the 3.5-28 MHz bands.
Sophisticated transformer element including line insulator.

The two arms of the radiator are galvanically connected via the transformer member - protection against static.
Resonant antenna fed by a 50 ohm coaxial cable.
The antenna resonates in amateur radio bands.
Depending on the influence of the installation environment, it is necessary to use an antenna tuner on some bands - the tuner built in the transceiver is suitable.

The radiator is one, fed off-center at a total length of ½ lambda on the lowest band.

Mounting for caliper attachment.
Only the CU-HS hoop variant can be hung by the ends of the arms and balun "in the air".

Technical data:
- 3.5-28 MHz bands
- total length of the emitter approx. 40 m
- arms are approx. 11 + 29 m
- the antenna is tuned to the length of the radiator
- antenna cable according to the selected variant
- OCF transformation element
- line insulator in the OCF transformer prevents sheath currents and interference
- Power load 300 W PEP max (SSB 300 W / CW 150 W / digi 70 W)
- clamp mounting
- box is IP-65 rated
- box size 105x105x75 mm
- PL connector (UHF), can be fitted with Amphenol N connector on request
- stainless steel fasteners

Optimum mounting conditions are: horizontal at 10m height and above, power supply with coaxial cable of the length of the impedance repeater on the lowest band used. Impedance repeater = ½ lambda x truncation factor (for the specific cable used)
Depending on the specific mounting design, the use of an antenna tuner on some bands should be considered, a built-in tuner in the transceiver is suitable. The quality of the ground, surrounding objects and environment, the height of the ends of the transceiver, the shape of the transceiver (horizontal, oblique, kinked, etc.) have an influence.

Radiation diagrams and other information can be found at http://www.ok5im.com/simocf.html

The box is supplied with a pressure valve.
The function of the pressure valve - if the instrument box is exposed to temperature changes - e.g. the difference between day and night temperatures or if heat is generated in the box during operation and the box cools down after operation - pressure changes and condensation of water vapour occur in the sealed box.
In some cases, a vacuum may even be created, which can cause dust and moisture to enter.
Installing a pressure equalizing valve is a very simple way to provide ventilation and at the same time prevent vapour condensation and dust from entering the cabinet.

Demonstration of attachment of antenna cable to balun mk2