One2Three Stackmatch qro.cz

Technical description

A stackmatch switch is used to distribute a transmit signal to several antennas or power amplifiers and to correct the matching accordingly. This is done using a special, large transformer and powerful relays.

The manufacturer qro.cz follows here a proven concept of OK2ZAW, the transformer uses a toroidal core made of C10A material (equivalent to -61 and -2ROT from Amidon). This core was specially selected according to the developer's requirements, it offers a significantly higher power handling than other toroidal cores. The usable frequency range goes from 1.8 to 30 MHz.

Remote control is via a 5-core control cable. All conceivable combinations of switching states are possible:

• TRx on one antenna (1, 2 or 3)
• TRx on two antennas (1+2, 2+3, 1+3)
• TRx on three antennas (1+2+3)

An unused antenna output is switched off.

The power consumption of the switch is maximum 3 watts, the switching voltage 12 to 14 V DC. The 3:1 Stackmatch is housed in a weatherproof aluminium casing, a mast clamp is included.

The specifications for the maximum permissible power (3 or 5 kW) are as follows:

• 100% in 'normal' CW, SSB and RTTY QSO operation (no contest). This means normal transmitting and longer receiving phases.
• 75% of the max. permissible power for CW and SSB in contest mode (approx. 50/50 transmit/receive).
• 50% of the max. permissible power for RTTY operation in contest mode, also FT-8.

Application description

The application possibilities of a stackmatch switch are very diverse. Due to the broadband transformer, monoband as well as multiband antennas can be used.

Typical applications are:

• Matching three identical antennas in the same direction to increase the antenna gain. Important in contests or DX.
• Connecting three antennas in different directions or with different directional characteristics to cover different regions at the same time. This is often very important in contests.
• Distribute the transmit signal to several power amplifiers and antennas.
• Selecting one, two or three antennas for reception improves the intelligibility of the other station, for example by fading out QRM.

The fact that very different antennas, for example directional antennas and omnidirectional antennas, multi-band and mono-band antennas, etc., can be connected together, results in a wide range of possibilities that offer many advantages, especially in contests.