Paul 9V1/KM7ABZ's FB SINGAPORE SolderSmoke Direct Conversion Receiver

Wow, I had been feeling a bit discourged about the slow-down in receiver completions, then I woke  up this morning and found this e-mail from Singapore.  My faith in ham radio was restored.  Welcome to the Hall of Fame Paul.  You get extra credit for doing it from far-off and exotic Singapore. 

Paul includes in his "proof of life" video not only some Malaysian SSB and some CW,  but also some very close-by China Radio International.  FB Paul.  

I also liked the way Paul used the local library to burn the schematic of the receiver burned into the board upon which it was placed.  And the library also 3D printed his PTO coil form.  

And ET confirmed Proof of Life!  FB! 

Be sure to check out the really nice build description in Paul's blog and Github page (links below): 

Paul writes:  

Hi Bill, Pete, and Dean,

I've finally made a "proof of life" video for you, plucking some CW, voice and shortwave signals from the 40 and 41m bands here in Singapore. What fun this was, and I am amazed at how well this works, even from the confines of my 15th floor apartment.

https://www.youtube.com/watch?v=Pek-wT96I2Q

Thank you so much for laying down the challenge - it came at just the right time for me, rekindling my enthusiasm and electronics and radio. It even encouraged me to finally get my license - I'm newly minted general class KM7ABZ (yet to get a 9V1 conversion license for my home here in Singapore). I can honestly say that listening to the SolderSmoke and Ham Radio Workbench podcasts since 2018 or so was worth *at least* 50% on the exam... somehow I already knew a bunch of stuff by pure osmosis!

Everything went pretty smoothly with the build. The only real issue I had was adding some caps to tame persistent motor-boating in the audio amp. Other than that, the build follows the official SolderSmoke schematic and parts selections.

I used the laser cutters at our local library to cut and etch a custom base. The library is a great resource: it’s also where I printed the PTO former.

To get on the air from my apartment in Singapore, I’m using an MLA-30 Active Loop antenna, with a PLJ-1601 frequency counter attached to the PTO to take some of the guesswork out of tuning.

All the details of my build are published at https://leap.tardate.com/radio/soldersmokedcrx/ (from GitHub).

Cheers,

Paul

KM7ABZ from 9V1 land

https://leap.tardate.com

______________________________

Join the discussion - SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

 

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

 

SolderSmoke YouTube channel:

https://www.youtube.com/@soldersmoke

 

"The New Essential Guide to Electronics in Shenzhen" A Book Review by Jenny List (with a video from Shenzhen)

This new book looks really good.  Great electronics info, with lots of cultural and linguistic wisdom. 

https://hackaday.com/2024/03/13/review-the-new-essential-guide-to-electronics-in-shenzhen/#more-668397 

Jenny's review brought to mind an older SolderSmoke blog post about Shenzhen. In this 2012 video  Bunnie Huang in Singapore talks about getting parts in that city: https://soldersmoke.blogspot.com/2012/08/singapore-knack.html

Thanks to Jenny, Naomi, and Bunnie.  

SW Echo Theory Confirmed By a BBC Engineer

BBC Relay Station Singapore

Hi Bill,

I heard your description of the echo on your podcast and before listening I knew the cause - but I think you know that now!

Yes, it's from two separate transmitters, and quite common, though not usually noticed.

It has nothing to do with path length differences - the longest round-the-world echo via the ionosphere is only about 0.15 seconds - so anything more has a different cause.

It's from the audio feed to the transmitter. Your regen receiver picked up two transmitters on different frequencies. It was very noticeable before transmitters used digital land-line feeds, just analogue and satellite.

On a BBC SW frequency (forget the which one now) one tx was in UK and the other in Singapore, on the same frequency with the same programme to completely different service areas. When propagation was right and listening in Europe, the UK signal fed by analogue audio from Bush House came first and the Singapore tx came with two geostationary satellite delays later, plus the tiny bit of UK-Singapore ionospheric path difference.

Now it's worse because there are all sorts of digital delays via land-line and satellite, although using the same frequency for the same service in not common.

In the UK Absolute Radio on AM medium-wave has multiple transmitters (mostly 1215 kHz and 1197 kHz) on the same frequency which are audible at night. If you listen carefully you can often hear multiple (up to FOUR!) echoes from different transmitters all being fed by different internet feeds/satellite links with varying delays. 

As an ex-BBC engineer, I can tell you that in the old days not only were these AM medium-wave group stations all synched to within 0.05Hz, but the phase of the modulation was adjusted so all tramsitters were modulating in phase! Now the commercial boys have taken over most of these syched groups, not only are the frequencies all over the place, but the modulation isn't even time delayed to match, let alone synchronized! Some even put diferent commercials in the breaks so if you're geographically between stations you get a complete, unlistenable-to mess. Apparently these days that's ok.

Why did we bother...?

Anyway, I hope this adds to and confirms your findings.

73,

Ian Liston-Smith, G4JQT

(A grumpy old retired BBC Engineer)

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Singapore Knack

Bunnie Huang has The Knack.  This was confirmed when, with obvious delight, he said that he'd found in China a book of schematic diagrams of a wide variety of laptops.  He then studied said schematics and endeavored to understand the role played by one transistor in the LED display of one of the computers.  KNACK CONFIRMED!  Somebody get Bunnie a ham license!  Cool video.  

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20