Thank you to all of you who have asked questions about my Portable Microwave Station. I hope the emails I have sent have gone some way to answering the many and varied questions raised. There has however been quite a number of questions asked that have centred on the main operating position and specifically how the Microwave Transverters are controlled from the operating position. This post will attempt to describe how I went about solving this issue and how I have assembled the HF, VHF and UHF transceivers that I use to ensure maximum operating efficiency while providing maximum protection for the equipment.
The centre console is built into a “roady” 19″ rack case that has been divided into two sections using a central divider on to which has been mounted a series of supports that hold the Transceivers.
Beginning at the top left is a YAESU FT8800R Dual Band (2m / 70cm) FM Transceiver. Under this Transceiver is a YAESU FT817ND (HF, VHF, UHF) Multi-Mode Transceiver that provides the RF drive and IF/PTT for the Microwave Transverters. The selection of which transverter is to be active is controlled by the control knob at the top centre.
Below this transceiver, still on the left hand side of the case, is an ICOM IC1200 (23cm) FM Transceiver. This transceiver and the FT8800R are connected to a Triplexer system that feed a Diamond Vertical that is located at the top of my portable mast. Primarily these two transceivers are used for liaison when operating portable. The YAESU FT8800R has the additional feature that permits it to operate as an FM repeater if required.
On the right hand side of the case is mounted an ICOM IC7000 (HF, VHF, UHF) multimode Transceiver that delivers SSB on all the band up to and including 70cm. This transceiver produces 100 watts PEP on all bands up to and including 2m and 75 watts PEP on 70cm.
Below this transceiver is an ICOM AT180 Automatic Antenna Tuner that operates up to and including 50 Mhz. This unit allows for tuning out a small mismatch when transmitting across the various bands.
The console has front and back covers that totally enclose the equipment when not in use. The case is made from very robust material and therefore has the potential to standup to the rigors of portable operation.
In addition access is also gained to the remote transverter connections that are positioned in the centre rear. This switching system is connected to the front selector switch using an extension shaft.
There are two connections on the to the remote switch, the one on the left provides 12volts DC to control the “Relay Switching Tree” and the second at the base is a 7 core cable connection that provides relay control of the relay tree.
On the lower lip of the case there are two pop-rivetts that support a small aluminium bracket that is used to anchor all the external cables using “velcro ties” thus removing strain on all of the connections.
The central bar that can be seen running across the rear of the box is an earthing bar to which all of the Transceivers are connected.
The seven core cable that is connected to the rear of the console is 10 metres long allowing the centre console to be placed in a convenient location well clear of the portable antenna system.
As shown in the photograph, the relay tree provides six (6) outputs for connecting to the Transverters. When active, a green LED is lit signifying the active output connection. Each connection provides an IF connection back to the YAESU FT817ND when receiving. In the transmit mode RF is sent to the selected Transverter with the PTT voltage sent to the Transverter via the centre conductor of the coax.
The following image shows the interior of the relay unit.
This view shows the six (6) relays and associated interconnections. The relays are labeled to assist in identifying what their role is in the overall operation.
The connector on the left hand side of the box accepts the RF, PTT and IF connection from the Transceiver.
The connector on the right hand side allows the seven core cable to connect to the relays.
The following images show the various components of the relay system.
The relays were positioned into cutouts in the double sided PC board to allow ease of assembly and to provide a ground plane that provides a low impedance grounding system for all of the components.
The enclosures used for the relay system are die-cast boxes that provide easy assembly and good protection for the components.
The system works well and makes the process of switching from microwave band to microwave band a very simple process. The LED’s positioned at the centre console and at the remote relay tree, make it a simple process to keep track of which transverter is active.
From an operational point of view, the system is very convenient and simple to use and makes the action of switching from band to band a very simple process!
I hope these few words and the accompanying images provide an insight into the way a central console and remote switched transverters can make portable operation more enjoyable!