END FED (EFHW) transformer mk3

Product detailed description

END FED Transformation Member

New design 2025

- more massive boxes, thicker walls
- brass bushings for lid screws
- Uniform box design across 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 a clamp mount version
- overall precision design

suitable for END FED (EFHW) antennas - end-fed half-wave antennas

Specifications:
- impedance transformation ratio 1:64 or 1:49 depending on the variant
- compensation capacitance 100 pF / 10 kV
- input impedance 50 Ohms
- Power load up to 300 W PEP max (SSB 300 W / CW 150 W / DIGI 90 W)
- large ferrite toroid 1x FT-240
- mechanical design for caliper mounting
- PL input connector (UHF)
- antenna radiators are connected to M4 screws and secured with wing nut
- fasteners are stainless steel
- box dimensions 105x105x60 mm
- the box has IP-65 protection
- the box is equipped with a pressure valve
- weight 0,4 kg

The box is equipped 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 valve with a pressure balancing function is a very simple way to provide ventilation and at the same time prevent vapour condensation and dust from entering the cabinet.

Example of attaching the antenna wire to the transformer mk3