Lots of fun and lots to learn from the Soldersmoke Direct Conversion receiver. It seems simple but there are some traps for young players like myself. Building with others and being able to compare observations is incredibly helpful.
My approach is Manhattan construction spaced out and arranged to look like the circuit diagram. This makes it easier to spot the inevitable errors but there is a downside that it's more likely to have instability. In the past few days I've re-built each stage in a more compact form and the result works well and has no instability. As an example of before and after here's the diode ring mixer prototype laid out for clarity:
Here's the new compact version of the mixer:
The compact VFO board:
Most challenging and most improved is the audio chain which is now stable even with the gain turned all the way up and the pot off the board connected with platted wires.
I did have a wiring error on the audio board that took me a little time to figure out. Having a working board to compare with really helped of course.
I'm about done with this project but it has been a wonderful learning experience. I would recommend this as a group project for any beginning constructors like me.
I visited my dear uncle Robert Glasser yesterday. Yes, Bob is really my uncle! He's 96 years old and doing pretty well considering.
Robert's short term memory is in serious decline. He introduced me to a carer about a dozen times. His long term memory is as sharp as ever and he was most entertained when I showed him a video of the Soldersmoke Direct Conversion receiver I'd built. He knew exactly what a direct conversion receiver is and was pleased that I'd gone on and built a double-sideband transmitter.
Robert told me that he'd got his call at age 16 and was W6HA (which he spelt out in phonetic letters). His carer was rather astonished at his sudden detailed technical conversation I think.
80 years a ham! I suggested he might be eligible to join the Radio Old Timers Club we have here. He doesn't get out much these days though. Here's a photo I took when I was quite young and clearly my focus was more on the gear than the person.
Wonderful to have him around but I fear our time is limited.
At AU$33 I couldn't resist ordering one of these little all band receivers with sideband.
Putting aside the speaker, which is so tiny as to be a joke, it does actually work rather well. Plugging in headphones or a powered speaker and you have a reasonable radio. However, the operation is quite annoying. The single knob with centre push must be double pressed to bring up a menu to choose things including volume by scrolling up and down.
A large part of the excellent screen is taken up with a silly dial display. Happily clever people have created improved firmware that makes better use of the screen and makes it more pleasant to use.
Then select the three files and enter the memory addresses like this (click to enlarge):
Note that you must use the "..." buttons and choose the files from your own downloaded and unzipped files. The offsets are 0x0, 0x8000, 0x10000.
When plugged in via the USB-C port and powered on, my radio came up as COM4 but yours might be different.
Click the Start button. When it finished, unplug the radio, power it off and on again. If all went well, it will show the version number. The first time I powered on I long pressed the encoder to wipe the flash.
There is at least one video showing this process but I find reading a web page a much better way to find out this stuff than watching a video.
The software is written using the Arduino platform and the ATS_MINI.ino file gives lots of technical information about the configuration of the radio including the display which is a TFT-eSPI device.
I had a shot at building the software in the Arduino IDE but ended up bricking the device. The Windows flash download tool was unable to write to it, even though the serial device was visible. Reading up on how other people got over this they recommended esptool which I used on the Mac and was able to get it running again.
Flash will be erased from 0x00010000 to 0x0006dfff...
Compressed 381552 bytes to 222197...
Wrote 381552 bytes (222197 compressed) at 0x00010000 in 2.8 seconds (effective 1082.1 kbit/s)...
Hash of data verified.
Leaving...
Hard resetting via RTS pin...
There is a PDF in the zipped firmware file that contains lots of information about the capabilities.
In the top bar there are two circular indicators. The first one flashes green each time the screen is updated. The second one flashes red each time settings are written to EEPROM. Saving settings happens about ten seconds after a change so delay turning the receiver off until you see the red flash or it will forget your latest setting change.
Victoria seems to have a good number of hamfests and today's at Yarra Valley was excellent. I bought a variable power supply which I hope is lower noise than my current one (remains to be seen), a bag of trim pots and capacitors for $2, an excellent electrical engineering text book, but mostly it was a chance to meet up with friends.
Nigel Holmes VK3DZ and Jim Gordon VK3ZKK
Ralph Klimek VK3ZZC
Drew Diamond VK3XU and Dave Stuart VK3ASE.
Warm congratulations to the organisers for a fantastic event.
