A major part of our plans for Satellite Station 4.0 includes the ability to operate our home satellite station remotely over the Internet. We’ve been using our Flex-6700 Software Defined Radio (SDR) as a Remote Operating Gateway (GW) on the HF Bands and 6m for some time now. Our latest project is to upgrade our Remote Operating GW to support satellite operations on the 2m, 70cm, and 23cm bands.
Adding the additional bands for satellite operations involves adding a 2m Amplifier, a 70cm Transverter, and a 23cm Upconverter to our SDR-based Remote GW. We decided to repackage our Remote GW set up in a rack mount cabinet on casters. This allows all of the required gear to be placed under the desk in our station in a way that is neat and reliable.
We also added an Ethernet Switch, a pair of USB hubs, and upgraded power and remote controls to improve our ability to manage our station remotely and to simplify the interconnections between our Remote GW and the rest of our station. The final assembly mounts all of the components in the rack on 5 levels as follows:
- Top of Unit – microHam Station Master Deluxe Antenna Controller and a K1EL Winkeyer
- Upper Shelf – WaveNode WN-2 Wattmeter and space for a forthcoming 23cm Upconverter
- Lower Shelf – 2m LPDA, 70cm Transverter, DIPs, and 28 MHz splitter
- SDR Rack Mount – Flex-6700 SDR
- Bottom of Unit – 8-port Ethernet Switch, Industrial USB Hubs, 10 MHz Reference Distribution Amplifier, and RigRunner 4005i Ethernet Controller DC Power Controller
These purpose of these components is explained in more detail below.
All of these devices are powered from 13.8 Vdc station power to avoid the potential for noise from wall wart transformers inside the rack. Also, attention was paid to the isolation of the digital and RF components on separate levels to minimize the chance that noise from digital signals would leak into the RF chains.
The diagram above shows how the added components for the satellite bands interconnect with the Flex-6700. The new components include:
- 75W Low Power Drive Amplifier (LPDA) for 2m
- 50W Transverter for 70cm
- 25W Upconverter for 23cm
- Diplexor/Switch (DIPS)
- 28 MHz Splitter
- 10 MHz Reference Distribution Amplifier
- LPDA USB Control Cable
- BITS USB Control Cable
- 12V Powered Industrial USB Hubs
The Flex-6700 can generate and receive signals on the 2m band but it does this at IF power levels. The 2m LPDA brings the IF power level up to a maximum of 75 watts. The DIPs device enables the Flex-6700 to operate in U/v, V/u, and L/v modes.
The 28 MHz splitter allows a total of 4 transverters/upconverters to be connected to the radio. This will enable us to add 5 GHz and 10 GHz bands to our satellite station in the future.
Our Flex-6700 includes a GPS Disciplined Oscillator (GPSDO) which provides an accurate and stable 10 MHz reference output to lock the 70cm and 23cm units frequencies. The 10 MHz Reference Distribution Amplifier expands the single 10 MHz on the Flex-6700 to drive up to 4 transverters or upconverters.
The two USB cables allow the Flex-6700 and SmartSDR to control the LPDA and PTT for the 70cm and 23 cm bands.
The rackmount arrangement uses shelves which provide ventilation for the components and enable us to use zip ties to tie down all of the components. The photo above shows the layout of the shelf which contains the 2m LPDA, the 70cm Transverter and many of the RF interconnections. Velcro tape is used to secure the smaller components to the shelf.
The photo above shows the RF interconnections. The 70cm Transverter is on the upper left and the 2m LPDA is on the upper right. The rectangular boxes coming from these devices are the sensors for the WaveNode WN-2 Power and SWR Meter that we are using. They are terminated in 50-ohm dummy loads for initial testing. The DIPS device is center bottom and the 4-port device above it is the 28 MHz splitter. All of the interconnections are handled using 50-ohm BNC cables and the unused ports on the 28 MHz splitter are terminated with 50-ohm BNC terminators.
The photo above shows the rear of the unit. The 10 MHz Reference Distribution Amplifier (bottom center) and the two Industrial 12V powered USB hubs are visible at the bottom of the unit. The DC power distribution components are at the upper left and a set of Internet-controlled relays are at the upper right.
One of the USB hubs fans out a single USB connection from the host PC to the USB controlled devices in the Remote GW rack. The other USB hub expands the USB outputs of the Flex-6700 to accommodate the control cables for the devices in the rack and the CAT cable which provides frequency data to the microHam SMD Antenna Controller.
Remote control and distribution of DC power to all of the devices in our Remote GW is an important design consideration. In addition to proper fusing, one must be able to remotely turn individual and groups of devices on and off remotely. The diagram above shows the power distribution and control architecture that we are using.
RigRunner power distribution blocks are used to fuse and distribute power to all of the accessory devices in the rack.
The RigRunner 4005i provides remote power control via the Internet for all of the major units and accessories in the rack. In addition to controlling power on/off states and providing electronic fusing, the RigRunner 4005i monitors voltage and current to the equipment in the Remote GW. These controls are accessed via a web browser and a network connection. Login/password security is also provided.
A microBit Webswitch device provides Internet controlled relays to manage various station functions including:
- Remote On/Off control for the Flex-6700 SDR
- Polarity Switching for our 2m and 70cm Satellite Antennas
- Control of our tower-mounted Low-Noise Amplifiers (LNAs) on 2m and 70cm
After some configuration of the Transverters and PTT controls in SmartSDR, the satellite portion of our Remote GW is up and running. There is quite a bit of software installation and configuration left to do and we’ll cover that in a future post.
You can find other articles about our Satellite Station 4.0 project here:
- Portable Satellite Station Part 7 – Plans for a 4.0 Station
- Satellite Station 4.0 Part 1 – New Tower
- Satellite Station 4.0 Part 2 – Antennas
- Satellite Station 4.0 Part 3 – Antenna Integration and Testing
- Satellite Station 4.0 Part 4 – Tower Camera and J Mode Desensitization Filter
- Satellite Station 4.0 Part 5 – New IC-9700 Transceiver
- Satellite Station 4.0 Part 6 – Tower Finishing Touches
- Satellite Station 4.0 Part 8 – GPSDO Frequency Locking