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13GHz Sig Gen - you can't be serious?

June 28, 2019, 7:38 am
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Well,

You may recall back here when I became very inspired by a project by GM8BJF using some eBay sourced Chinese modules to create an ADF4351 based signal generator.

There's another variation on that theme that has been published in the May 2019 Scatterpoint. Scatterpoint is the journal of the UK Microwave group, membership is about 3 bob and a conker so you have no excuses for not joining.

This time it uses an ADF5355 to generate signals from 52MHz all the way up to 13.6GHz.

The 4.4GHz generator has proved extremely useful, this one is a must.

I've modified the design and the software a little so that the 100MHz clock is generated by am ADF4351, rather than an OCXO as per Brian's design.

Brian has made the software available here, and my modified version is here. The AD4351 is a version of the evaluation board from SV1AFN - and it gets its reference from my 10MHz shack frequency reference.

The software runs on a SAMD21 ARM Cortex M0 which runs at a 48 MHz clock rate. This is supported by the Arduino IDE but is not something I had used before.


Its still WIP, but the project is up and running OK.


How cool is this?
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Even More Power!

August 11, 2019, 2:16 am
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Well,

I've been messing about and finishing off my 13cm linear. The idea is to make something that will work on the 2.3GHz amateur band frequencies as well as 2.4GHz for DATV on Es'hail-2.

This has been quite a challenge, but eventually we have something working ready for on air testing.

This is the final build, which even though I say so myself, is a masterpiece:


The PA module itself is something from my travels made by PowerWave:


There are five MOSFETS in total - each one is a SRF7068H5HS.

This is controlled by a W6PQL Amplifier Control Board which in turn uses an external FET switch to turn on and off the 12V bias lines to the PA, provide the sequencing necessary, generate an ALC voltage (just in case I need it later), generate an external PTT out for switching VLNAs or other external gubbins.

There's also a chassis mounted directional coupler (a NARDA model 31152) which provides a -30dB forward and reflected port output which is attenuated and rectified to produce a DC voltage. There's a forward voltage for a future power meter and also a reflected power voltage to activate a trip if the SWR should exceed 2:1.


I've even included a thermistor on the main heatsync and a trip in the amp control to switch on the fans or even shutdown the amp when over temperature.

I'm seeing about 26dB of gain from the amplifier and it will generate about 250W of CW on 2.407 GHz so should easily generate the 30-40W I might need for some DATV experiments.

Here is the unit under test, I'm using the Portsdown to generate a signal at 432.75 MHz, then using the mixer from the UK Microwave Group forum to mix in 1975 MHz to generate an output on 2004.75 MHz. This is then amplified up and fed to the linear. The forward port of the directional coupler (-30dB) is coupled via another 20dB attenuator to my XL Microwave meter. A short piece of coathanger shoved into the front of the Spectrum Analyser allows me to measure the harmonics and also look at the TX waveform.


A thing of beauty is a joy to behold! I'm delighted with this.
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Up-converting - you what?

August 13, 2019, 10:15 am
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Well,

Further to the PA I made last time, today I have been finishing off the up-converter to accompany it.

The theory goes something like this:


  • The Portsdown will output DATV on 439 MHz through the transverter output
  • This will be sent down the garden in Ecoflex-15
  • The co-ax losses will be compensated for using the 70cm amp I made back here
  • This will feed the SG Labs transverter we played with back here
  • The output of the transverter is then boosted by the Wi-Fi amp from here 
  • Finally the output is fed to the PA
Here's the up-converter in its finished form, there's a simple sequencer in there to handle the PTT switching and send a PTT signal to the PA:



Tomorrow I hope to install this and the PA in the small shed I have near the dish - then for some on-air testing.

This is the output of the up-converter DVB-S, SR250, FEC 1/2 - received with an antenna across the bench:



** UPDATE**

I've not yet installed the equipment in the garden, so I have about 4-5dB minimum of cable loss between the PA and the dish feed. However, here's my first RX of my own TV signal through Es-Hail'2:


** UPDATE 2 **

I've moved the gubbins to the small shed near the dish:


And am now sending 439MHz (ish) down the garden from the Portsdown.

This is a 333KS transmission via QO-100, you can see my signal on the left of the Mini Tioune software at 10,497.750 MHz:


And here is a testcard:



Local conditions.
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Radio Analog PTRX-7300 - Really?

August 17, 2019, 11:54 am
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Well,

You may well have seen adverts for the PTRX-7300 from Radio Analog. This is some kind of new fangled adaptormabob for the Icom IC-7300 that gives you an RF output that you can hook up to an external SDR for a panadapter display.

Well, I ordered one.

Here are the bits that you get (but not the screwdriver):


You start by taking the radio top cover off:


Then we disconnect the cable that attaches to the rear external tuner connector and remove it:


Then the new gubbins clips into the space where the external tuner connector was:


Hook up the cable into the now vacated socket for the external tuner connector:


and then pull a plug out of the radio PCB and insert into the new gubbins:


Then we have a supplied cable from the new gubbins to the PCB socket we just disconnected:


And thats it! Now externally the tuner connector is re-connected and also a flying lead with an SMA connector to feed to the SDR. This is extremely neat!


So once we have all that done, I have set up SDR Console:


and it just works.

Simples!
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DVB-S2 - really?

August 24, 2019, 4:16 am
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A very quick special message broadcast on the QO-100 Digital Amateur Television:


Local conditions.
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JARTS - doesn't time fly

October 19, 2019, 9:19 am
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Well,

It's the JARTS RTTY test once again and the bands are full of RTTY signals.

Propagation contitions are very poor, but there are plenty of signals about.

I've been using the IC-7610 today and it's a superb RTTY radio:


The internal decoding capability is also excellent:


Here is the 40M band early on the Saturday evening - CW and RTTY everywhere!


Here's a map of my log:


Local conditions.
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Practical Electronics - Really?

December 2, 2019, 2:14 am
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Well,

I recently built myself a project that had featured in the Oct/Nov 2019 issues of Practical Electronics (previously Everyday Practical Electronics). It is a new fangeld GPS-synced Frequency Reference.

It uses a CDCE906PWG4 from Texas Instruments as its core component which allows three independent outputs to be set over a wide frequency range.

It also uses a thingamabob called the Micromite Backpack - which is basically a microprocessor with a nice colour touch screen integrated that is designed to use MMBasic as its programming language.

The theory of operation is very simple, there is a 40MHz ovened variable oscillator and also an external GPS 1pps signal. The microprocessor counts the 40MHz signal between 1 second pulses from the GPS and adjusts the voltage control on the oscillator appropriately. Once we have an accurate 40MHz signal, this is then used by the PLL to create the reference outputs at the user selected frequency.

Unfortunately I can't get this thing to work (properly) and I **think** my fundamental problem is one of power filtering/decoupling.

Here are the basic components, the green board is the frequency reference and the red one the Micromite.


The white wires on the board you can see are a suggestion from the author "the stability of the reference may be improved by reducing the impedance of ground tracks on the PCB" which smells rather fishy to me.

Anyhow, the output of the oscillator from the PLL looks like this:


and the output, when set to 10MHz looks like this:


All looking rather nasty - wouldn't you agree? The bursts of apparent crap on the signal are when the GPS is sending data to the processor.

I've tried to get some support for this project; but failed rather dismally. There used to be a chat room for EPE projects, but that has been closed. There is a dedicated forum now, here:

https://www.eeweb.com/forum/category/epe-magazine

but I posted there over a week ago, was notified that my post is subject to moderation, but it still hasn't appeared. I also note the last post there is over a month ago.


All of the self tests in the software appear to pass; that suggests all is well, but I can assure you that all is not well at all! The output frequency is a mile from being accurate, the "approx freq" in the screen above swings wildly around the 40MHz target suggesting the processor is having issues counting the clock, and generally it's all a bit pants.

Not sure what to try next.

This makes me sad.

I even ended up digging out a CD4046 to remind myself how PLLs work,


In the image above, we have the source oscillator from my desk function generator in yellow, the light blue is the output from the on-chip VCO, the purple is the basic comparator (type 1) output and the darker blue the type 2 comparator output. When I change the frequency of the bench generator the on-chip VCO follows in frequency and locks - just as it should - I remember now!

Alan Wolke, W2AEW, has a superb video explaining this stuff on YouTube here.

This, however, makes me very happy as it is our very beautiful Pepper Cat enjoying a bit of late winter sun:


Local conditions.
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More ADF4351 - really?

December 7, 2019, 2:23 am
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Well,

You may recal my dissapointment back here with the Practical Electronics GPS-synced Frequency Reference.

It turned out to be a load of Dingo's Kidneys.

You may also recal the most excellent work of Brian, GM8BJF back here using the ADF4351.

Well, I have been playing with the Micromite that was used in the Practical Electronics project, and have created a touch screen signal generator using the ADF4351.

It's very much stolen from a project here.

I've modified the code a bit to have an additional digital output to show the PLL locked state, and also changed the code to use a 10MHz clock rather than the default 25MHz clock.

It's quite neat!



Albeit upside down:



I'm 3D printing a case for the front, then we can decide what to do with it:


The output is as I expected:


I've uploaded my bodged version of the code here.

Good, isn't it?
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More ADF5355

January 2, 2020, 7:15 am
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Well,

Following on from my great invention last time, I've been fiddling some more with the ADF5355 that we used here.

I've done something that feels a little silly, but is working:
  • I have developed some code for the MicroMite to do touch screen control
  • That communicates over a serial connection with a SAMD21 ARM Cortex M0 which does the complex double precision maths needed for the ADF5355
It feels a little silly to be using two processors, but:

  • The MicroMite doesnt support the double precision maths needed for the ADF5355
  • I can't find an easy to use library to do the graphics and touch screen gubbins on the SAMD21
So we have two pieces of software.

The ADF5355 board is from Amazon and looks like this:


You can get one here.

The touch screen proides the facility to view the current selected frequency:


and enter a new one:


Once you have entered the frequency the MicroMite sends the selected frequency as a string to the SAMD21 processor which then does the necessary maths to generate the 13 register values used by the ADF5355 and squirts them over the SPI interface.

The ADF5355 uses a 100 MHz clock which is generated using the ADF4351 from last time which in turn is clocked by the shack 10MHz frequency reference.

The initialisation of the ADF4351 is done by the MicroMite over SPI, the SPI to the ADF5355 is from the SAMD21 processor.

Here is an example of the 13 register values being sent:


and a close up of one of them:

This will need boxing and turning into bench test gear.

The Basic code that runs on the MicroMite is here and the code for the SAMD21 (using the Arduino IDE) is here.

Here is the very lovely Miss Luna Cat who has assisted throughout:


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STM STM32F103RC8T6 - really?

January 12, 2020, 12:26 am
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Well,

On popular auction sites you can find these boards for less than 2 GBP delivered:


They contain (on the underside) a STM32F103RC8T6 processor from ST Microelectronics. Looking at my musings from here, these boards will support the necessary double precision maths and also have the SPI interface needed for frequency synthesyser interfacing - amazing!

These will work with the Arduino IDE with a very small amount of effort.

Assuming you already have the Arduino IDE installed (if not go get it), the steps are:


  1. Go to the Tools -> Boards -> Board Manager and install the Arduino SAM boards (Cortex-M3)
  2. Download the STM32 support package from here.
  3. Unzip the download to create the Arduino_STM32 folder
  4. Copy the Arduino_STM32 folder to My Documents/Arduino/hardware (Note: if the hardware folder doesn't exist you will need to create it).
  5. Navigate to My Documents/Arduino/hardware/drivers/win and run the install_drivers.bat file - right click and run as Administrator
  6. Restart (or start) the Arduino IDE and select "Maple Mini" as your board, "Original" as your bootloader
  7. Attach the board to the PC with a USB cable, you should see a "Maple DFU" device under "libusb-win32 devices"
You could then try this sketch and upload it to the device; please note that at this point you don't have a COM port for the board - it is using the bootloader via the DFU device instead.

Once the sketch is loaded you will then see a COM port "Mapel Serial" which you can now also select in the Arduino IDE tools -> Port.

I've connected my board to my SV1AFN ADF4351 board as follows:

STM32F103RC8T6 Pin 7 -> SPILEA (pin 3)
STM32F103RC8T6  Pin 6 -> SPICLK (pin 1)
STM32F103RC8T6  Pin 4 -> MOSI (pin 4)
STM32F103RC8T6 VCC -> 3V3 (pin 7)
STM32F103RC8T6  GND -> GND (pin 5)

and have run this sketch - seems to work just fine.

I then ran this sketch - and followed the instructions in the Serial Monitor to upgrade the bootloader - once I'd done that I then needed to select Tools -> Bootloader Version -> 2.0 for any future comms with the board.





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Spectrum Analysis

January 19, 2020, 1:23 am
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Well,

I've been messing about recently with some inexpensive alternatives to a Spectrum Analyser. I find my Rigol DS-815 one of the best investments I've ever made, it represents excellent value for money. However, its still an expensive purchase and I wondered if the inexpensive alternatives were any good.

First off, I tried one of these that you can source on all good auction sites, here is a link to the device on Amazon:

Without a box

and also:

With a box (if you are posh like me)


They look like the image above and represent exceptional value for money - you couldn't purchase the bits for the price.

Here's my evaluation of the device:


Second I tried an SDRPlay and associated software as a Spectrum Analyser:


Next will be a Red Pitaya... so watch this space.
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Back to the BITX

February 1, 2020, 11:21 pm
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Well,

I wanted to do a simple (ish) construction project for my YouTube channel and decided a BITX would be just the ticket.





If you like what I am doing please subscribe to my channel and give me some support.

Thanks muchness!

** UPDATE **

Following the issues I noted in the video on balancing the Balanced Modulator, I have added some capacitance either side as highlighted in this image:


By careful adjustment of the balance pot and the trimmer I have now got excellent carrier supression:


much better, dont you think?
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A STM32 Processor - really?

February 1, 2020, 11:30 pm
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Well,

In my never ending desire to fiddle with Microprocessors and/or Micro controllers, I found these boards on my local Amazon with prime next day delivery:


They are called a "Blue Pill" for some reason?!?!? The boards I ordered are these. At the time of writing I could buy 5 of these boards for £15 GBP delivered.

You can use them directly with an external USB -> Serial converter, but you can also upload a bootloader and make the on-board USB port work successfully.

I followed the instructions here:


the speed of these processors is excellent and when used in conjunction with the ILI9342 displays I have been using recently they work very well indeed.

You can see an example of the processor in action in my latest musings on the BITX:


All very impressive and I still fail to believe how inexpensive these MCUs are.
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Making a 10W "QRP" ish linear

February 14, 2020, 1:54 am
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I've started to design some software that will control a low power linear amplifier.

I plan to use the 10W Amp from QRPLabs as the main component - I can't make one for the price they sell these kits, so thats on order.

In the meantime, I've been designing some software to control the output switching, and calculate the forward and reflected power and SWR:



Initial software design is included for the STM32 "blue pill" baord.

The software can be downloaded here.

The pinoput for the STM32 board is here.

The schematic for the RF sence using AD8307 is here.

You can purchase a STM32 board here.

The TFT display with touchscreen functionality is here:

More to follow on this topic.
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TFTs and Blue Pills - Are you sure?

March 11, 2020, 10:30 am
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Well,

I've been using the STM32 processor (STM32F103 for those playing along at home) based "Blue Pill" board. This board is compatible with the Arduino IDE and I have been using it with the ILI9341 super duper TFT display module.

This is the board in question:



The STM32 board support can be added easily to the Arduino IDE, just add this line:

https://github.com/stm32duino/BoardManagerFiles/raw/master/STM32/package_stm_index.json

to the preferences screen:


Once you have done that you can then install the STM32 cores from the board manager:


I wrote some very simple code to generate Pi using floating point maths:


Set to calculate 100,000 itterations, the good old Arduino Nano ran this code in 29.60099983215332031250 seconds. This Blue Pill board runs the same calculation in 3.07200002670288085937 seconds. Cooking!

Here' how I have wired the test up for the TFT:


I have used the library called "TFT_eSPI" which is here. In the more modern Arduino IDE you just search for it and install from the library manager.

Once you have done that you need to make a couple of edits to the "User_Setup" file which you can find in the libray directory.

Here's mod 1:


and this is mod 2 - please use pins of your choice here:


Once you have done that all should be well!
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Article 0

March 25, 2020, 10:44 am
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Well,

I've been fiddling some more since the Linear we built a little while ago here.

Some musings below on power meters, directional couplers and measuing RF power:



I hope you are all keeping safe - its very scary out there.
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A CW & WSPR Beacon

April 18, 2020, 9:06 am
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Well,

I've been fiddling some more with STM32 and have created a DDS based CW & WSPR beacon for 6M.

You can find the details of the project here:


The WSPR code is by Anthony F4GOH, his code and other bits and bobs are on GitHub here:

https://github.com/f4goh/wspr

Fun, dont you think?
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TS-890 (Again) - Digital Config

April 19, 2020, 4:06 am
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Well,

By popular request I have created my best shot at an "idiots guide" to setting up digital modes on the TS-890:


I hope this is useful to someone....
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GPS Disciplined, again?

April 30, 2020, 3:22 am
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Well,

I've been trying to learn more about STM32 microcontrollers, their programming and to understand more about the on-board peripherals.

This is the result of my musings:


Fun, egh?
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A Modest Milestone

May 9, 2020, 5:11 am
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