We’ve recently received our L24TX Transmit Converter from Down East Microwave. The unit is compact, simple, and produces up to 25W output in the satellite section of the 23 cm band (1260 MHz – 1270 MHz, actually 24 cm). The L24TX is a transmit-only device that is intended to enable L-band uplinks for Satellite use. This article is about our most recent project which involved integrating the L24TX into our Flex SDR Satellite System.
24 cm Tx Converter Rear Panel
Connecting the unit is straightforward. The unit requires an IF input, a 10 MHz reference oscillator, DC power, and a transmit keyline. The later two inputs are provided via a 7-pin connector and a DEM supplied cable. We ordered our unit with the following configuration options:
IF 28 Mhz = 1260 MHz output
Max IF Drive Level – +10 dBm
Fan and Case configured for mounting in the shack
Fortunately, our feedlines for the 23/24 cm band are hardline-based and relatively short. The unit is also available in a configuration that would enable it to be remotely mounted in an enclosure on a tower.
24 cm Tx Converter Installation in our Remote Gateway SDR Rack
The unit fits nicely into our Remote Gateway SDR Rack. The L24TX does not include a power output display so we used a 23/24 cm sensor and our WaveNode WN-2 Wattmeter to monitor output power from the unit. The unit does have leads that output a voltage that is proportional to output power. This could be used to build a power output bar display or meter. the front panel indicates display a power-on indication, lock to the 10 MHz clock input, and Tx when the unit is transmitting.
Overall Satellite SDR System Design
Integration into our Satellite SDR System was straightforward. Our system already included splitters for the 10 MHz GPSDO and the 28 MHz Transverter outputs from our Flex 6700 SDR. I had hoped to use one of the leads from the SmartSDR BITS cable we are using to key our 70 cm Transverter but the BITS cable did not have an adequate drive level to key the L24TX.
Remote SDR Gateway Tx Band Settings
Fortunately, the Flex 6700 has configurable TX1-TX3 outputs for keying devices like Transverters. The use of the TX2 output to key the L24TX was easily configured in the SmartSDR’s TX Band Settings.
23 cm Tx Converter Setup in SmartSDR
It is necessary to configure SmartSDR for the L24TX. The required settings are in the XVTR options tab. In addition to configuring the mapping between the Flex 6700’s XVTR IF frequency and the unit’s output Frequency, one needs to set the IF drive levels. We used the default drive level of 6.0 dBm and adjusted the IF Gain Control on the L24TX until the full output of 25W was reached while transmitting a tone. The correct adjustment is apparent when further gain increases do not provide a proportional increase in output power. The proper setting of the RF drive and gain will keep the L24TX’s output in its linear range of operation.
SDR Satellite System Remote Power Control via a RigRunner 4005i
The RigRunner is remotely accessible over the Internet and our network via a password-protected web interface. This enables us to easily power down or power cycle individual components in the Satellite SDR System remotely.
MacDoppler Tracking AO-91
With all of the hardware installation and calibration steps complete, we are turning our attention to the software side of the setup. We will be using MacDoppler for satellite tracking and VFO control of our Satellite SDR System. This creates a need to connect the MacDoppler program which runs on a Mac to SmartSDR and the Flex 6700 which is a Windows-based system. Fortunately, MacDoppler provides a UDP broadcast mode that transmits az/el antenna position information as well as data to control radio VFOs to adjust for Doppler shift.
FlexBridge Software Beta
We are working on a custom windows application called FlexBridge to enable MacDoppler to run our Flex SDR-based Satellite System. FlexBridge runs on a Windows PC. It receives and parses the UDP broadcast messages from MacDoppler and uses the FlexLib API to properly configure and control the Flex SDR’s VFOs.
SmartSDR Operating With AO-92 in L-V Mode
At present, FlexBridge can configure and control SmartSDR (or a Maestro Client) that is operating our SDR Satellite System. The screenshot above shows the MacDoppler, FlexBridge, SmartSDR combination operating with AO-92 in L/V mode. This software is still an in-progress development and we plan to add the ability for FlexBridge to connect to the radio via SmartLink as well as support for the Green Heron RT-21 Az/El Rotator Controller that we are using. We’ll be sharing more about FlexBridge here as the software development progresses.
The next step in our Satellite Station 4.0 Remote Gateway project will be to move our satellite antenna controls and feedlines into the shack and begin testing the complete setup using local control. Once this step is complete, we’ll focus on the final steps to enable remote operation of our satellite station via the Internet.
Here are links to some additional posts about our Satellite Station 4.0 Projects:
Frequency accuracy and stability become more challenging for transceivers that operate at 400 Mhz and above. Our 4.0 Satellite Stations operate at frequencies approaching 1.3 GHz and we want to be sure that their operating frequencies are accurate and stable. Our Flex-6700 SDR includes a GPS Disciplined Oscillator (GPSDO) so the radio and all of the transverters associated with the radio use the radio’s GPS disciplined 10 MHz output for frequency synchronization.
We choose a GPSDO from Leo Bodnar. The unit is compact, USB powered, and comes in a nice case which includes a GPS antenna and a USB cable. The unit has two GPS disciplined frequency outputs which can be configured for a wide range of frequencies and levels via a Windows application.
GPSDO Connected to an IC-9700
The GPSDO is connected to the 10 MHz reference input on the back of the IC-9700 with a BNC to SMA cable and the GPSDO is powered via a USB connection to our iMac. We configured the GPSDO output frequency to 10 Mhz and for an output level of +7.7dBm (drive setting 8mA). We also added a 20 dB pad in line with the GPSDO output to better match the drive level requirements of the IC-9700’s 10 MHz input.
The GPSDO will lock in a very short period of time (less than 1 minute) once GPS antenna and power connections are made the unite t. The unit has a red LED on each of its outputs and the unit is GPS locked when the LEDs are on and not flashing.
Configured and 10 MHz Input Locked IC-9700
The last step in the setup process is to configure the IC-9700 to sync its reference frequency to the 10 MHz input. This is easily done in the IC-9700’s Set/Function Menu.
It was pretty easy to add GPSDO locking to the IC-9700 and the arrangement described here works well. While this upgrade is not essential for satellite operation, it’s nice to know that our satellite transceiver frequencies are accurate and stable.
You can find other articles about our Satellite Station 4.0 project here:
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:
The 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.
Remote Satellite SDR System Design
The diagram above shows how the added components for the satellite bands interconnect with the Flex-6700. The new components include:
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 transverter 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.
2m/70cm Shelf RF Interconnection Details
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.
Rear View of Remote Gateway Rack
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.
USB Connections via Hubs
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.
Power Control and Distribution Design
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 devices on and off remotely. The diagram above shows the power distribution and control architecture that we are using.
13.8 Vdc Power Distribution
RigRunner power distribution blocks are used to fuse and distribute power to all of the accessory devices in the rack.
Remote Gateway Power Controls
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.
Remote Control Relay Unit
A microBit Webswitch device provides Internet controlled relays to manage various station functions including:
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:
The IC-9700 is based upon Icom’s direct sampling SDR platform. It supports all modes of operation on the 2m, 70cm, and 23 cm bands. The radio also supports satellite modes and D-STAR.
MacDoppler Controlling the IC-9700
The new IC-9700 replaced the IC-9100 in our Portable Satellite Station. An updated version of MacDoppler is available which supports the IC-9700 and we tested MacDoppler using both the USB and CI-V interfaces. In both cases, MacDoppler handled the new radio including band and mode selection, doppler correction, and access-tone setting properly. Our setup uses an iMac running MacDoppler and MacLoggerDX for radio control, antenna control, and logging and a windows laptop running UISS and MMSSTV for APRS and SSTV. Our setup was easily accomplished by connecting the IC-9700’s CI-V interface to the iMac and the USB interface (for audio and PTT) to our windows laptop.
IC-9700 Display and Waterfall – Working FO-29
We’ve made about 50 contacts with the IC-9700 so far. The radio is a pleasure to use. The touch screen layout and functions are very similar to the IC-7300 and one does not need to spend much time with the manual to become comfortable using the radio. The Spectrum Scope and associated waterfall are really nice for operating with linear transponder satellites. The screenshot above shows the IC-9700 display while working contacts using FO-29. As you can see, it is very easy to see where stations are operating in the passband of a linear transponder. The Spectrum Scope also makes it very easy to locate your signal in the satellite’s downlink and then adjust the uplink/downlink offset for proper tone.
We’ve also done a bit of APRS operation through the ISS using the IC-9700 and the UISS software. The direct USB interface was used to a windows laptop for APRS. Setting up PTT and the proper audio levels were straightforward and the combination of MacDoppler controlling the VFO in the radio and the PC doing the APRS packet processing worked well.
The IC-9700 can power and sequence our external ARR preamplifiers and we plan to use this capability to eliminate the outboard sequencers that we are currently using with our preamps. We’ll need to climb our tower to change the preamps over to be powered through the coax before we can complete the preamp control changeover.
All in all, we are very happy with the new IC-9700 for Satellite operations. We’ve also noticed that quite a few satellite operators also have the new IC-9700 on the air.
You can find other articles about our Satellite Station 4.0 project here:
The performance of the 3.1 Station’s antennas is very good but the antenna system is a handful to transport. We are planning to install these antennas on a new tower at our QTH and use our Flex-6700 SDR-based Remote Operating Gateway with some upgrades to create a remotely controlled satellite station that can be operated via the Internet. The main components of the 4.0 Station will include:
Upgrade plans for our Transportable station include the addition of remote switchable polarity relays and a new Icom IC-9700 Transceiver when it becomes available.
Polarity Switch Installed in LEO Pack Antennas
The polarity switches have been installed on the M2 Antennas 436CP16 and 2MCP8A antennas in our M2 Antennas LEO Pack. We are using a DX Engineering EC-4 console to control LHCP or RHCP polarity selection on the antennas. We have been doing some testing with the upgraded LEO pack which includes the polarity switching capabilities and we are seeing a significant improvement in performance.
AlfaSpid Az-El Rotator
We are also planning to move the upgraded LEO pack antennas to the current 3.1 Tower to take advantage of the AlfaSpid Rotator which is installed there.
Icom IC-7900 Transceiver
The other major upgrade planned for the 2.2 Station is the new Icom IC-9700 Transceiver when it becomes available. This radio will utilize Icom’s SDR platform and includes a Pan Adapter/Waterfall display which will be a very useful addition for operation with Linear Transponder Satellites.
Upgraded Portable 1.2 Station
We really enjoy mountain topping and activating grid squares so we are planning upgrades to our 1.2 Station for this purpose.
Our 1.2 Portable Satellite Station on Mt. Kearsarge
The 1.2 Station utilizes computer control to enable operation with linear transponder satellites and will use solar/battery power along with a 100w/70w Icom IC-910H Satellite Transceiver.
A pair of 90W foldable solar panels, an MPPT solar charger, and a pair of LiPo 4S4P A123 batteries provide plenty of power to run the IC-910H Transceiver and the associated computer. The portable station also includes a pair of ARR preamps.
Portable Satellite Antenna System
The antenna system we’ll be using is an Elk Portable Log Periodic 2m/70cm yagi on a camera tripod. A combination of a compass and an angle finder gauge helps us to correctly point the antenna.
As you can probably tell, all of these upgrades are in progress and are at various stages of completion. We will post updates here on our Blog as we continue to make progress. Here are links to some of these posts:
The IC-9700 is a new VHF/UHF radio that is based upon the Software Defined Radio (SDR) platform that Icom uses in the IC-7300 and IC-7610.
It looks like this is going to be an excellent radio for Satellite, EME, and other weak-signal work on the 2 m, 70 cm, and 23 cm bands. The IC-9700 features a pan adapter display which will be very useful for working contacts through linear satellites.
Based upon previous new Transceivers release by Icom, I would guess we are at least 8 months to a year away from the time when this radio will be offered for sale in the USA.
Here’s some video of the forthcoming IC-9700 as well as other gear from Icom. The video also features other new products and updated Firmware capabilities from Icom. Enjoy!
The installation of the latest version of WSJT-X software to add current JT9, JT65, FT8, MSK144, and WSPR digital modes to our Remote Operating setup
These steps are now complete and we have some good results to share.
SmartSDR V2 Remote Connection
The first part of the upgrade was to update to SmartSDR V2. This upgrade enables much improved SmartSDR operation over the Internet. Our previous approach, which used a tunneled VPN connection combined with the previous versions of SmartSDR did not always perform well when used with low-bandwidth or high latency Internet connections. SmartSDR does much better in this area.
SmartSDR CAT Remote
Both the SmartSDR CAT and the SmartSDR DAX application have been updated to allow software on a PC being used to operate the FlexRadio SDRs over the Internet to gain access to CAT and sound interfaces associated with the radio.
FlexRadio Maestro Console
We also added a Maestro Console to enhance the usability of the SDR radio portion of our Remote Operating Gateway. The Maestro is very easy to use and extends the available controls and display space which was limited when using just a laptop PC. The Maestro supports direct microphone connections for phone operation and also works with connected CW paddles for operation in CW mode. I have been using a single level paddle along with our Maestro as speeds of 22 WPM with full QSK. Sending CW at these speeds with the Maestro works well.
The Maestro has built-in WiFi and Ethernet connections and full support for SmartSDR V2’s connections over the Internet. The Maestro can operate from AC power or from an internal battery pack. I have a couple of spare rechargeable batteries for our Maestro to support longer operating sessions on battery.
With the addition of the SmartSDR and the updated TeamViewer/VPN setup, we can operate our station remotely over the Internet. We have tested our setup using a Wireless Hotspot modem and Verizon’s LTE service. The combination of our PC running the DXLab Logging Suite and the Maestro work great in this configuration.
We have found the need to initialize the networking configuration in a specific order to get everything running correctly. The steps that we use are as follows:
Connect the laptop PC to the Internet
Bring up the TeamViewer VPN connection
Run SmartSDR on the laptop PC and login to SmartSDR Remote
Bring up the DXLab’s Suite including Commander (currently, DXLab’s Commander has some issues connecting when the FlexRadio protocol is used. We have found that the KENWOOD protocol works fine.)
Bring up the remote control application for the Elecraft amplifier and access our RigRunner power controller and microBit Webswitch units to turn on accessories as needed
Initiate a second TeamViewer Remote Control connection and use it to run the microHAM remote antenna controller in a single window
Shutdown SmartSDR on the laptop PC and bring up the connection to the radio via the Maestro.
There is obviously still some room for simplification in this initialization procedure. I expect that some simplification will come as all of the software involved becomes more mature and is further adapted for remote operation.
Once initialized properly, its simple to use the PC and Maestro combination to work SSB Phone or CW contacts. The DXLab Logging Suite will follow the radio, track modes, handle split operation, and allow control of our antenna rotators via DXView. We can click on spots in DXLab’s SpotCollector to automatically set the FlexRadio SDR’s mode, frequency, and split configuration. The Maestro and DXLab will stay in sync during tuning, mode changes, and other radio operations.
Remote Digital Operation using WSJT-X and FT8
The final part of this project was to add the latest Version of the WSJT-X software to our Remote Operating client laptop PC to enable FT8 operation on the HF bands and MSK144 for Meteor Scatter work on 6m.
These enhancements to our Remote Operating Gateway have helped both Anita and me to operate more. I have our Maestro either in my home office or on a table in our kitchen where we can listen to the bands and work DX when the opportunities come up. Remote Operating, even it’s just from another room at your QTH, is great fun!
We have been quite impressed with the performance of our Icom IC-7300’s radio’s receiver. As a result, we have decided to upgrade the second radio in Anita’s operating position to an Icom IC-7610. We expect that the IC-7610’s receiver performance will be as good as or better than the IC-7300.
Icom IC-7610 External Display
The Icom IC-7610 also provides a very nice external display capability which will allow us to take the best advantage of the radio’s pan adapter. We believe that the IC-7610 will integrate easily into our microHAM system. It should be a “drop-in” replacement for our current IC-7600. We hope to see the IC-7610 shipping before the end of this year.
Elecraft KPA1500 Legal Limit Solid State Amplifier
Our microHAM Station Automation System can accommodate shared amplifiers. We will take advantage of this capability when we integrated the Elecraft KPA1500 into our station. The shared amplifier setup will also allow us to eliminate one of our bandpass filters. The KPA1500 amplifier integrates autotuner and wattmeter functions into the amplifier and provides a direct Ethernet interface for remote control and management. These enhancements should eliminate the need for several of the remote control server software applications that we are currently running on a PC in our shack. Also, we can manage all of these functions from a single client application on a remote client PC. These simplifications will make our remote operating gateway setup more reliable and easier to use.
FlexRadio Maestro Control Console
We plan to share more on these projects in future posts here on our Blog. The FlexRadio Maestro and all of the other components that we need for Remote Operating Gateway enhancements have arrived. We will complete this part of our project in the very near future and post more here.
Also, it appears that the local control interface to the new Elecraft KPA1500 amplifier is nearly identical to that used by our current Elecraft KPA500 Amplifier. This means that we can begin our shared amplifier upgrades using the KPA500. We do not have a firm date for the IC-7610 to ship and that portion of our upgrade plans is likely to be our last step in the project.
Special thanks to Dave, K1DLM who has helped us with ideas for several aspects of this project.