160mtrs antenna selection box


For 160mtrs contest operation a multitude of receive and transmit antennaes needed to be controlled and selected. Some of the antenaes will be powered by a seperate poweramplifier. For ease of operation a remote control was needed for quick selection of one of the receive antennaes.

Feature list

  • One transceiver input
  • Two poweroutputs for driving a seperate poweramplifier
  • Selection of receive antenna out of
    • Beverage antenna
    • TX antenna 1 (e.g. vertical)
    • TX antenna 2 (e.g. dipole)
    • K9AY loop, 4 directioins to be selected
  • Remote contol
  • Pre-amplifier, low intermodulation
  • Narrowband bandpass filter



Main controller

Main controller contains the RF part aswell as the control logic


RF Main controller contains all RF circuitry:
a number of RF switches/relays, attenuator and bandpass filter.


Logic part of the controller

Power divider

In order to drive both a GU43 amplifier and the FL2100 both to full output the powersplitter will split the TX signal in two unequal power levels. The GU43 amplifier is a tetrode amplifier and needs approx. 50W for 1500W output, on the other hand the triode base FL2100 needs 100W to get to the 800W power level. Power splitter is a lumped element discrete spliiter
To be inserted picture powersplitter
To be inserted schematic diagram power splitter

Bandpass BC reject

To reject strong MW broadcasting BC signals a narrow band bandpass was build. Bandpass is based upon the N3NQN design but will use smaller size toroid cores for the inductors. Original design was using big ferrite torroid cores as this was used for TX as well.

Remote controller


Selecting the RX antenna is done with a remote control. This remote control consists of 7 push button's and accompagnied indication. Antennas to be selected are Vertical, Dipole, Beverage, K9AY North West, North East, South East and South West

to be inserted picture schematic diagram remote control

Receive pre-amplifier


To lift the received signal strengths from the K9AY loop and beverage a low intermodulation type of amplifier was used. Design used a medium power transistor 2n3866 (with small heathsink) and bifilar wound toroid transformer in a straightforward manor.

Operating condition's:

Iq = 20 mA
Power Gain = 20 dB

Copyright © 2011 Carel Mobach, PC5M

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