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Combined transceiver with antenna concept


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What follows below is a combined 'first post' of a very long discussion that was taking place on a closed message. We just felt that it was interesting and worth sharing with everyone up front. Let the discussion also continue here.

 

ORIGINALLY POSTED by @WA3LTJ:

Lynn, there is an idea that I have been thinking about for a while that maybe you can provide feedback on. It is not far from the CRT2-mini. Note, I have a moderate amount of experience with mixed signal and small embedded systems. A few of my creations are products, some are running in a research laboratory, and many are for my own education (and amusement).

 

REPLY by @KU7Q:

 

Andy, I was quite surprised when my articles landed in QEX. I'm pretty sure it wasn't because of the highly technical nature of them (no formulas or theory). I think it was more because they were niche articles that didn't appeal to a wide audience. QST seems to prefer more generic articles.

I'd be happy to comment on your project idea. My background is in electric utility communication systems O&M, but I've always dabbled in creating devices and systems that helped the maintenance technicians do a better job. The last 5 or 6 years I've focused on small embedded systems. I enjoy the process of bringing a new idea to life and I'm so stubborn that I don't stop until it is doing exactly what I want. The last 10% of the project takes 80% of the time. But that's OK. I'm retired now and it fills my days.

 

REPLY by @WA3LTJ:

 

Lynn, I have been thinking about various ways to combine transceivers and antennas together as a single package. Conceptually, this is not new. A handheld radio is a transceiver with the antenna on top. A mobile radio and a repeater are stations where the transceiver, power and antenna are collocated. 

Right now I am thinking about making a remotely operated POTA station. The antenna can be a loop antenna on a tall lighting stand with the radio and battery just below. However, the radio, battery and controller could be one package used with any of several antennas. If Jim had his way, the package would have a wide-range antenna tuner. 

I expect to run 100W. The operator accesses, tunes and operates from 10 to 50 feet away. This should not be difficult. The loop antenna uses a motor-operated capacitor. Tuning requires switching the transceiver to 5 W and monitoring the SWR reading. After that, radio operation is relatively simple in POTA operation. I want to run SSB, so audio will need to run in both directions. 

The ideal package will be waterproof and not difficult to carry or set up. I envision operating remotely from a picnic bench, car or tent. I figure Wi-Fi is a good control link. There could even be a dedicated access point on the ground half way between the station and control site, if necessary.

Thoughts?

 

REPLY by @KU7Q:

 

Andy, The remote control part isn't that hard to do, even over WiFi (I already do that on my CTR2-Mini). The complexity comes when you want to move audio between the radio and the controller on WiFi. On the radio end a Raspberry Pi with the right software could handle everything you'd want to do. The user end is more problematic. The obvious answer is to just run a cell phone or tablet and use a browser with HTML5. That's where the bulk of the complexity comes in.

In my opinion, if you're only needing to run 10 to 50 feet WiFi is overkill. A controller like my CTR2-Mini could handle almost everything you're describing (albeit you may need to drop the CAT rate down to 4800 baud if you're going 50 feet). In it's native mode the Mini only handles CAT, PTT, and Key to control the radio. It has a radio dashboard that lets you easily control many of the settings on the radio. My new CTR2-Mini Audio Controller adds the ability to push transformer isolated Line-In and Line-Out audio across the CAT5 control cable to the new CTR2-Mini Audio I/O module (described in the link above).

I actually have a new Mini design almost ready for a board run. I'm tentatively calling it CTR2-Max (Mini on steroids 🙂) because it integrates the Audio Controller into the current Mini's design and uses the new Audio I/O module instead of the Radio I/O module. It does require an external box to allow for all the required connections.  It wouldn't take much to design a wireless antenna tuner control interface based on an Xiao ESP32-C3 with a small display to go along with the Max. The ESP32 in the antenna tuner controller could use Bluetooth or be set up as a WiFi IP access point. The Max would connect to it the same way as it connects to my CTR2-Mini Antenna Switch Controller.  It would be easy to modify the current External Tuner page to display power and SWR and allow the encoder to control the motorized cap on the loop.

The user control end would be just the CTR2-Max, mic, headphones, and paddles. You would need a battery at the control end or you could run a pair of wires to the battery at the radio end. The Mini draws about 200 mA at 12VDC. The radio end would be just the Audio I/O module connected to the radio and the new antenna tuner controller connected to the antenna tuner. Since the Mini/Max already has the ability to control a wide range of radios this configuration gives you the opportunity to choose the radio and antenna/tuner that works best for you.

Here's a drawing of what I'm thinking about.

CTR2-Max_POTA_Configurationv10.drawio.png.50694a17f8c867abe12e25e69a4ca3c0.png

This may not be what you're looking for, I'm just throwing out ideas,

73, Lynn

 

REPLY by @WA3LTJ:

Lynn,

I am just beginning to understand the CTR2 architecture. I appreciate your familiarity with the challenges and your interest in the problem. A few thoughts:

In 2019 I designed a self-tune circuit for the loop antenna. It actually used an ESP32 (Sparkfun Thing) and matching motor driver board. I like the ESP32 processor except for the lousy A/D converter. The Thing has been replaced by a different board as part of a standardization with Adafruit. I have been using the Feather M0 recently. I think they have a WiFi version. The self tune circuit used a RF clock generator board to sweep a signal and a RF log amp to sample the main loop element. I could strip down that design and make a simple motor controller. I would need some way to start and stop the motor with low latency through the wireless network. I am not sufficiently familiar with HTML5 or PHP to accomplish that.

I did not realize the difficulty of streaming audio. I am familiar with the Raspberry Pi. I built an application for playing videos and streaming sites. It uses VLC. SSB POTA operation benefits from rapid contacts. After doing remote rig contesting, I have learned that a quick turnaround is not always easy to implement. 

I do not want to use a CAT5 cable in the POTA solution. It would be fine in some circumstances, but I learned in Canada that sometimes the path between the equipment and the operating seat is not one to lay a cable. People can trip and fall, or the route for a cable is much further than the line-of-sight. 

It would be great to have a COTS solution to my POTA idea. I don't mind having a PC, tablet or RPi at the operating position. I am a little concerned with the power budget at the radio. 200 ma continuous draw is perhaps the limit of what I would like to burn. I use a 20 AH LiFePO4 at the moment. Unfortunately for the battery, I am used to operating for 3 hr straight. That is easily the limit of the battery with the radios I use. 

Just my thoughts.

Andy

Sparkfun Thing tuner.jpg

 

REPLY by @KU7Q

Andy, I can appreciate wanting to be wireless due to tripping hazards. I was just brainstorming how the Mini could be used in this situation. Thinking about it, if you're Ok with a laptop running at the control site your best bet is a Raspberry Pi on the radio end running Node-RED for control using JavaScript for CAT and PTT, not Key, and run the Sonobus audio server on the Pi and on the laptop to handle the audio. The difficulty comes if you want to support more than one CAT protocol, control different types of tuners, or use CW. Node-RED eliminates the need to do the HTML stuff.

73, Lynn

###

THAT'S THE END OF THE ORIGINAL POSTS.

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  • Elmer


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I have seen an example of Node-RED and it looks very nice. I helps people like me who have not looked at HTML since 3.0.

All together, it does not seem like a quick or easy project, but very doable. I would rather just plug in a Mini and let the experts do the development. If your work takes you in this direction, let me know. I am not completely against testing a wired solution, but the fundamental concept is cutting the cord.

I have only one CAT protocol, Yaesu. I can debug with the FT-dx10 and then probably go to a FT-891 (that Jim talked me into). I will look up the Sonobus server. Can I use it in both directions? I think that is what you imply. I wonder if a Raspberry Pi 3B+ has sufficient MIPS for this application? I like it better than the Pi 4 because it does not need a cooling fan. I have both, so I will start on the 4 and then test the final product on the 3B+.

Thank you very much for your input. I hope I can find someone who wants to join me in the project. I'm not retired yet!

Andy

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  • Elmer


Andy,

Yes, it is very doable. Sonobus is bi-directional. It was developed to allow musicians the ability to jam together remotely. It has very low latency and is point-to-point (i.e. it doesn't use a cloud server in the middle). It can be installed on almost any operating system including Windows, Apple, Linux, Android, and iOS for iPhones and iPads. I haven't used it but I think Mumble can do the same thing.

I actually developed a pretty extensive Node-RED application for my original CTR2 radio controller a couple of years ago (I retired CTR2 last year when I started on CTR2-Mini). I used Node-RED to replace the Nextion display I was using on that system. It had all the control necessary for what you are talking about including a latching PTT button.

Thinking about this problem, it would be relatively easy to re-spin the CTR2 control board into a Pi Hat. If I did that all the CTR2 software for what you see below is done and the Node-RED code is ready. I think I just got inspired to create a new project 🙂

Here's a few photos from the CTR2 implementation so you can see what I'm talking about.

CTR2_Demo_on_Pi.thumb.jpg.ccdb6b3bd1fd5ee352cc66b270c6aeca.jpg

Node-RED running on a Raspberry Pi 3B+ controlling the CTR2 radio controller below the Pi. It intern controls the radio it's connected to (off screen). Node-RED is running in the Pi's browser. The same display and control is available to another browser on the network that connects to the Pi's Node-RED IP port.

 

Node_red_home6.png.3d75ca91498b95fb92ddf45fada35242.png

Full Node-RED main display for CTR2.

 

And a simple drawing to show a possible configuration.CTR2_POTA_Configuration_v10.png.841d8a1e06f0c4027c4d4690ce5c4b6b.png

 

73, Lynn, KU7Q

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  • Elmer


As you think the plan through, I can set up a test platform here. I have a Yaesu rig and the Pis. The two Yaesu rigs have internal USB CAT controllers. I assume the Pi can use those. The FT-891 does not have a sound card (the FTdx10 does). Both have some sort of rear audio port. I have a motor controlled capacitor for testing. We may need an H-bridge to drive the motor. 

I have a small HTMI screen for the Pi, but I  don't think it has a touch screen. I can  use either a monitor or ssh with the Pi. 

I'm not sure what else might be needed. My laptops all run Windows 10/11. 

 

 

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  • Elmer


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Andy,

Unfortunately CTR2 and CTR2-Mini don't support USB CAT. The Teensy 4.1 on CTR2 has a USB host port but it only supports very generic devices like keyboards and (I think) USB memory sticks. Radios that have CAT and audio on their USB ports use one of several USB host chips and they usually aren't compatible. That means the host must have driver software that recognizes each chip and knows what to do with it. This scheme works fine on a PC because you just load a new driver to support that chip. It's not that easy on a microcontroller.

For that reason, CTR2 and CTR2-Mini only support serial CAT ports and analog line-in and line-out connections. Also, Node-RED is running in a browser so if you use a Pi with a miniature display for the operator location you'll have a difficult time seeing the display. I'd recommend a laptop or tablet for the operator end. The current CTR2 hardware supports the small Nextion touch-screen displays but I won't be carrying that interface over to this new board (CTR2-Pi??) because it's too difficult to keep four firmware packages in sync (CTR2, Node-RED, and 3.5" and 5" Nextion code). Just keeping CTR2 and Node-RED sync is enough trouble for me.

I have a wide range of radios to test with here and several Pis (FTdx101D, Flex 6400, Xiegu G90 and X106, FT-817, etc). I also have a Alex Loop I can play with if I had a way to rotate the tuning know (it's a four turn cap). The bottle-neck is just time and other projects. I'm finishing up the latest new products for the CTR2-Mini line so I won't be able to even look at this again for a couple of weeks. It's definitely something I'm interested in looking at though.

73, Lynn

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  • Elmer


It all makes sense to me. I think both Yaesu rigs have legacy connectors. 

My idea of a setup here was just to mirror your development and field test when possible. I'm not adverse to buying things for a project like this. 

There is no rush on my end. The idea has been kicking around for more than a year. I have a few other ideas/projects that also deserve attention. 

BTW, I just submitted my article. It took about a week to write. 

Tnx

Andy

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  • Elmer


I dusted off my Raspberry Pi 3B and 4 today. I am going to start with the 3B because the 4 is in a custom box at the moment. I burned a fresh Raspberry Pi OS. I want to install Node-RED. I assume it is available in the standard Pi repository. If not, I will still find it. I discovered I have two 5" touch screens and one larger HDMI screen.  For now I will use a full size monitor/keyboard/mouse. I assume I can use a desktop Windows computer on the network for testing the remote end. That is what I have most available at the moment. I assume Node-RED recognizes the digital I/O ports of the Pi. If I want to do a serial connection to a rig, will I need a USB to Serial converter or is there a standard way to send/receive serial from the I/O pins? I need to see if my rig has a +/- 5v serial port or a TTL type serial port. 

Once the rig is under control of Node-RED, I guess I can install some widgets and make the rig do a few standard tricks. When that all works, I will think about a motor controller. Finally, I will need to understand the audio paths. Do you use the Teensy 4.1 Audio Adapter with the Raspberry Pi, or do you need to include a Teensy 4.1 controller? (The controller has a lot of horse-power!) I don't understand if the audio adapter's library can work with just a Pi.

Andy

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  • Elmer


Andy,

I worked on the CTR2-Pi design idea yesterday and have come to the conclusion that resurrecting my old CTR2 project is probably more than I want to take on. It's not as simple as just loading my Node-RED code into the Raspberry Pi and building a Pi Plate for the Teensy 4.1 and Teensy 4 Audio Adapter. For one thing, they won't fit on the footprint of a Pi Plate. I'd have to build them as a base board and mount the Pi on top. Basically the CTR2-Pi ended up as a streamlined version of the original CTR2 system... and it would require massive code changes to gut out the old interfaces that wouldn't be needed and add the additional functionality that is needed (i.e advanced radio control options).

In the original CTR2 system the Teensy 4.1 controlled the radio through an external radio I/O module. The Teensy Audio Adapter did all the audio processing. Node-RED running on the Pi just mimicked the Nextion display, nothing else. There's no code in Node-RED that controls the radio. I loaded SonoBus on the Pi  and connected it to a USB audio card plugged into the Pi that was patched to CTR2's mic and headset jacks to transport the audio from CTR2 over IP. The original CTR2 worked well but ended up being overkill and too expensive. I think the same can be said for trying it to adapt it to this application.

According the the web the Pi 3B+ pulls 400 mA when idle with no USB devices plugged in and WiFi off. WiFi will add maybe 200 mA more. Adding the Teensy hardware adds another 100 mA+. That's pretty steep overhead when all you're trying to do is move audio and radio control over a wireless link in a POTA setup.

One option I'm thinking of looking at uses CTR2-Mini and designing a wireless Radio I/O module using Xiao ESP32C3 modules. One wireless Radio I/O model would be connected to the Mini at the operators position and be set as a WiFi access point and the other would be connected to the radio at the RF location and set as a WiFi station. They would pass the CAT and PTT signals from end to end. Audio could be handled by a Pi at the radio location running SonoBus or some other audio server. The PC at the operator position would use a USB headset with mic and use the PTT on the Mini to key the radio. I think you could also connect WSJT-X to the digital audio stream from SonoBus.

Even this seems like a overly complicated for a POTA station just to get a little distance from the operator and radio/antenna. A CTR2-Mini with the CTR2-Mini Audio Controller, 50' of CAT5 cable (run in a garden hose to weigh it down or elevated above ground to minimize trip hazards) connected to a CTR2-Mini Audio I/O module at the radio would be a much cleaner solution. No Pi would be needed at the radio end and you have mic/headset jacks and audio available for a USB sound card at the PC for digital modes at the operator position. I just measured the current draw of the Mini and the Audio Controller, it's 120 mA... much better suited for POTA operation.

For the loop antenna controller I'm looking at using the Xiao ESP32C3 WiFi module controlling an H-bridge. I can easily add code to the Mini to support connecting to it over WiFi and issuing raise/lower commands to the capacitor motor while in External Tuner mode. I just need to display the SWR from the radio and use the left and right switches on the blue 5-way switch to control the raise/lower command. I've ordered some parts to start playing with this idea when I have time.

Consider all of this as still brainstorming. I'm open for suggestions.

Lynn

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  • Elmer


One thought so far is that perhaps your current calculations are at 5v. The POTA station runs on 12.6v. A carefully selected buck regulator can run with 80 to 95% efficiency. So, the current budget is about twice. I think 200 mA at 12v is tolerable. The ESP32 has numerous low power modes. There may be ways to support idle periods. 

 

Andy

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  • Elmer


The Mini’s 120 mA draw was taken from the 12 v input. You are correct on the Pi current, I just pulled it from the web. From my experience the Pi complains about low voltage if you run it on less than a 2.1 amp 5 v supply. I have a buck converter coming in on Monday so I can test the actual 12 v draw then. 

One other option for audio would be a Bluetooth headset but then your limited to  30 feet and it’s iffy if you can use it for digital modes. 
Lynn

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  • Elmer


I spent part of today installing Raspberry Pi OS on a RPi4. I installed Node-RED, Sonobus (with SNAPS). I researched audio cards for the Pi. I think I understand that the Teensy 4 audio shield works specifically with the Teensy 4.x, a high performance controller board. Direct connection to the Pi GPIO pins (primarily using the I2C bus) can be done with: Audio Injector Sound Card ($35 from Australia), Wolfson Sound Card from Seeed Studio ($34 out of stock) or Pisound ($118 from Europe somewhere). The I/Q audio boards are mostly output, but the Codec Zero is a $20 board that can do I/O. I don't know it's latency. Adafruit has a cheap USB sound dongle that works with the RPi. I don't know anything about its performance.

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  • Elmer


I may have to relax the power budget to accomplish my goals with the remote station. That will not be too bad for a system running a 100 W transmitter. I spent some time exploring the low power modes of the ESP32 (there are a whole group). I used the deepest sleep mode with timed wake-up. I don't know much about the Raspberry Pi power reduction modes except the Pi 4 throttles down if the chip gets too warm. I think if you are interested in the power consumption of the Pi 4, you might find the power usage to be very dynamic. I suspect the low voltage warning is driven by peak current demands. The 2.1 A / 5 V supply prevents voltage sags during peaks, but not badly. I use a special power box for my Pi 3B and 4. It is a 120 V open frame 5v/3A switching power supply with filtering and added choke. I adjust the voltage to 5.2 V (the maximum allowed from a USB port). It is the only power supply that can run my video player along side a treadmill without impacting the performance of the player. I will be curious what you learn. I have a MFJ-4403, which is just a box with 4 F of capacitance for 12 v. I suspect something like that for 5 v would prevent the undervoltage warnings seen with more typical wall transformers. I have never tried that.

 

 

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  • Elmer


Thank you. I just looked at it. Like all Pi things it is overpriced while the Pi 4 is not very available. It has an audio board that might be useful. The software is open source.

I am playing now with one of my RP4s.  I tested a USB audio dongle and it seems to work with VLC and Audacity. I installed, ALSA, Jack2 and Sonobus. I have a USB serial port (Prolific) and that seems to be recognized. I want test it with a rig using Flrig (an offshoot of Fldigi). I still want to get more familiar with Node-RED.  I don't quite know where to start. Somewhere there must be good examples of flows for sending commands to the radio. In fact, I think you published files that do exactly that. I need to dive in and learn enough to get a rudimentary system running so I can do some end-to-end testing.

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  • Elmer


With the RigPi being open source you can just download it and compile it in your Pi4. It’s code might give you some ideas. 
 

The Node-RED code I published doesn’t do rig control, just CTR2 control. CTR2 controlled the radio. I’ve taken most of the CTR2 pages down since there was only a couple of hams that were interested it. 
 

Lynn

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  • Elmer


I am surprised that so few hams showed interest.

I have written code for a Feather M0 to control the FT-dx10. I can do that now with the Pi (or use some of the RigPi code). The Laptop does need to see changes in the SWR meter while tuning up the loop. I think I should monitor the SWR reading with the Pi and then "inject" messages going to the laptop. This is something like the CTR2.  That seems to fit the Node-RED way of doing things. I think I will set up a sort of simulation of SWR readings and get the Pi and laptop talking.

I feel a little awkward writing code on the Raspberry Pi. Python seems most popular there. I am more comfortable with C. I have been using an old IDE (Code::Blocks). RigPi is written in Python 3 by someone who knows PHP, HTML5 etc.

I also read that the internal sound card and serial CAT port on the FT-dx10 work with the latest RPi OS, so I may be able to connect directly to the rig.

 

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  • Elmer


Connecting through USB is the way to go. It’s much simpler, as long as you have the driver for their USB chip. 
 

CTR2 just evolved into a solution looking for a problem (but oh what a learning experience!). I stripped all the advanced features out that nobody seemed to want and came up with CTR2-Mini. The Mini has seen more success but the audio routing options will add to the overall cost. The nice thing about the Mini is you can start small and cheap and expand as your needs change. 

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  • Elmer


I started CTR2 in April 2020 when the lockdown started. I published two articles in QEX about it, Sept/Oct 2021 and Jan/Feb 2022. I stopped working on it in December 2021 when couldn’t get the parts to build it, even if there would have been some interest. I’m into the Mini 14 months now. I wouldn’t say it’s mature yet since I keep coming up with new ideas for it regularly 🙂

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  • Elmer


Andy,

I just wanted to give you an update on where I'm at with my remote CTR2-Mini based radio/loop antenna project.

I have a working tuner/rotor running for my Alex Loop. It's controlled with a Xiao ESP32S3 and uses WiFi to connect to the Mini. The ESP32 is nice in that it can be a WiFi station or AP so I put a switch on the controller box to allow me to select between the two modes. In the shack I'm using it in station mode, in the field I'll use AP mode.

Here's a photo of the current configuration:

image.png.5af263c158787d272622f807a2b1bc89.png

The tuning cap is controlled with a right-angle 2 RPM gear drive motor. The Alex Loop is nice because it uses a 3.5:1 reduction knob with a clutch so it just slips if I tune past the ends. The Mini has four tuning modes, Slow, Medium, Fast, and Turbo. Fast mode helps you find the Rx noise spike then I shift down to Medium or Slow to bring the SWR down.

The rotor uses the same gear drive motor. It's at the bottom, just under the back control box and is fastened to a plate tie-wrapped to the tripod's cross supports. It's coupled to a 24" section of 1/4" all-thread that travels from the base up through the tripod shaft and into the loop's lower PVC section. There's a coupling at the top of the all-thread with a notch in it that interlocks into the nut rivet that is used to mount the loop tuning box. The loop's lower PVC pipe mounts on the shaft of the tripod and sits on the tripod's base plate. For portable use this will work fine. It's not meant to be mounted permanently outside. Both motors are coupled to their respective controls using double-sided Velcro so it's easy to remove everything.

I'm working on a power sensor that will interface to the Xiao to send forward and reverse power to the Mini for tuning. I currently use the radio's SWR meter in the Mini but this makes it usable with other radios that don't support SWR metering (i.e. any radio without a built in tuner).

My plan is to put my G90 in a case with a battery and place it below the tripod. The tripod will be tied to the radio case so it's weighted down and tent pegs will keep everything on the ground. I'll control the G90 and the tuner/rotor with the Mini using CAT5 cable. I'll probably have my XYL sew up a simple canvas "tee-pee" covering that will snap around the tripod if it looks like rain 🙂

Let me know how you're project is proceeding. Did you get Node-RED running on your Pi?

73, Lynn

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  • Elmer


Lynn,

You are making a lot of progress in far less time than it has taken me. I think I understand most of the description. I don't see much use for the rotor. The antenna has a sharp null along the horizontal axis. In my portable experience I "point" the antenna so that any big signal (usually another POTA station in the same park) is in the direction of the null. The interesting signals are either NVIS or skip, which is nearly omnidirectional with a loop. That said, having the rotor might be useful on occasion.

The slipping clutch is an interesting alternative to a limit switch. I really want to install a limit switch on my linear cap, but at the moment the pencil markings (actually very useful) are my only way to get the tuning on the desired band. 

If the loop has a very high Q, most directional couplers with a Log RF power sensor chip will work. The ESP32 has a lousy A/D converter, but I was still able to use it for the log amp detectors. What I found worked even better than a directional coupler was a RF sampling loop coupled to the main antenna loop through a toroid. I used the same log amp, but instead of bothering with a SWR measurement, I just tuned for peak signal. It worked very well.

I am making progress with Node-RED.  I use rigctl (HamLib) with the exec node to control the radio. I took a few days off to teach myself Javascript. I avoid learning new programming languages whenever possible, but this was essential.  I find that commands sent to the FTdx-10 are very slow to execute (by my standards). I also very much dislike the entry options (e.g., drop down menus, sliders) for the GUI. I guess I can buy into a better toolset, but right now I am still working on the proof-of-principle. I recently started using the rigswr HamLib command to sweep a ham band and plot a SWR curve for the antenna. This uses the rig's SWR capabilities. It works well enough. My next steps are 1) implement motor control with the Raspberry Pi via the GPIO pins. I ordered a TB6612FNG breakout board. 2) implement network audio. I have some notes based on our conversations and I think I picked out an appropriate network audio application. The FTdx-10 has built-in audio through the same USB port as the rig control. 

I find this sort of work very slow going. Everything is a learning curve, little goes smoothly and I don't have a lot of free time work on it. I don't have a proper space. I squeeze the Pi and my radio on my office desk for a few days, then pile it on the floor when I need the desk space. The latest Raspberry Pi OS comes with a Node-RED package, but I had to deleted it and do a generic port of Node-RED because the FTdx-10 driver file is only available on the most recent builds. So it goes. Fortunately, your guidance early-on has been, and continues to be, a great time saver.

Andy

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  • Elmer


True, the rotor isn't a necessity, but the H-bridge board had an extra port and the motor was only $15, so why not. My idea is to have just the Mini and Surface Pro on the table and the radio and antenna 10 to 20 ft away.

That may change as I go forward. Preliminary testing shows that with 5 watts into the loop the ESP32 shuts down just as the loop approaches resonance and starts radiating power. The ESP32 and H-bridge sit just below the loop so I added 10nF caps to all the inputs and outputs but still had to add an toroid choke to the power supply input to keep the ESP32 happy. The ADC inputs from the remote sensor are also bouncing around and are currently unusable. I know most, if not all of this is that I just built the ESP32 and H-bridge into a plastic case I had kicking around so I have an aluminum case coming. The Xiao ESP32 chip has an external antenna connection so I ordered an 2.4 GHz antenna with a jumper so I can mount the antenna outside the box. That should cure the RF issues.

The Alex Loop has an RF indicator on it that glows when the loop is resonate so if I can't resolve the instability issues with the power sensor I may just do away with it and just use the rotor to turn the antenna toward me when I peak the power then turn it back to whatever direction works best.

73, Lynn

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  • 2 weeks later...
  • Elmer


Lynn,

I have a few minutes to write an update. At this point I have Node-RED running fairly smoothly on a Raspberry Pi 3B+ (and a 4B). I am beginning to understand Javascript and its integration with Node-RED. I have some crude, but useful interfaces to adjust the FTdx-10 transceiver (Frequency, mic, AGC, preamps, mode, bandwidth, etc.), run and plot a SWR sweep on all or part of a band, and run the loop antenna motor at any selected speed for n seconds (using hardware PWM and a TB6612FNG breakout board for the GPIO). The rig control is via Hamlib. Motor control is a command-line program written in Python. It uses gpiozero for GPIO and rpi-hardware-pwm (HardwarePWM) libraries. 

The Raspberry Pi works headless using SSH and VNC.  I have local audio working (more or less) using Sonobus on the Pi and the PC. I have some refinement of the GUI to do, then I can do a bench test with all the moving parts. I will put the Raspberry Pi and a laptop on a WiFi LAN using my cellphone as a hotspot. If there is cellular signal, then it also provides an internet connection for the laptop. Otherwise, it is essentially just an access point.

The current draw from the 12v battery is not trivial, but I look forward to getting a 100 W station on the air. 

Andy

 

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