Bert's EMRFD Direct Conversion Receiver

Very nice Bert.  Sounds great.  I like the pill bottle coil core.  Lew McCoy used them in his designs. I do think that air core coils do provide better stability than ferrites or iron powder.   I kind of like the SW broadcast background music.  I also like the internal 9V battery.  Glad to see someone else resurrecting an old DC RX project.  


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

VFO for BITX 20/40

Here's the VFO I use in my BITX 20/40.   IF is obviously 11 MHz.   VFO normally tunes 3697-3859 kHz for 40 meters.  Switching in that 220 pf cap lowers the range to 3292-3189 kHz for 20 meters.  It workd very well.   The coil is wound on a cardboard tube from a coat hanger.  I will put this in the appropriate file on the BITX group site.    I like the 20/40 band combination:  Good DX possibilities on 20, with provisions (40!) for the low sunspot counts to come.

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

Manhattan meets Hyderabad: Pad Pattern for my BITX 20/40

A rough guide to how I laid out the isolation pads on my BITX 20/40 board.   The copper-clad board is 8 inches x 11 inches (22 cm x 28 cm).  I just cut out the pads as needed using tin shears and scrap pieces of copper clad board.  Gorrilla SuperGlue is my preferred adhesive.  I will put this in the appropriate file on the BITX 20 yahoo group site.


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

Our New Robotic Overlords

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

Homebrew Blimp with paper-thin Arduino (Printoo)

More on Printoo (very interesting!):

https://www.kickstarter.com/projects/1030661323/printoo-paper-thin-flexible-arduinotm-compatible-m


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

Hackers Recover 1960's Moon Pictures

http://www.wired.com/2014/04/lost-lunar-photos-recovered-by-great-feats-of-hackerdom-developed-at-a-mcdonalds/

Thanks to Mark, K6HX, for alerting me to this wonderful project.   

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

Pete Juliano's Bilateral Rigs (with videos)

 

Hi Bill,

 

I was finally getting around to reading one of the recent SPRAT’s and saw a photo of your magnificent BITX17. Congratulations! A tip of the hat to Farhan for that very excellent design and it truly is a design that has traveled the world and made a radio available to many who otherwise would not be on the air.

 

It is a very robust design as I scratch built one in 2005 (or maybe 2006) and just for fun socketed every transistor so I could try various devices. I even had a bag of 2N706’s dating back to the late 1960’s. They all worked except for the carrier oscillator where I just couldn’t get enough swing in the oscillator to correctly place the CIO on the filter slope. That I attribute to the junction capacitance of the 2N706. By far the lowly 2N3904 that I bought for 4 cents each worked the best. Back when I built this I was W6JFR. Adding the EI9GQ frequency stabilizer really added a nice touch to the radio.

 

I should also tell you that when I built the radio my intent was to uses a piece of single sided copper vector board for the main chassis. It was the weekend and I didn’t realize the piece I had was not  big enough for the project. So I took a piece of standard perf board and overlaid that on top of a piece of single sided copper PC board –AND hand drilled all of the holes – I went blind, cross-eyed and had a terrible hangover after consuming 6 beers in a short time span! See the photos below.

 

BTW I also built a 17M SSB transceiver using the bilateral amp stage from G4GXO as appeared in the SPRAT 128. That used a 4.9152 MHz IF and a 23 MHz Super VXO. In the case of the VXO I used 11.52 MHz crystals in the VXO and used a diode doubler to put the LO at 23 MHz. With the doubler –you get the bonus of 2X the frequency shift of the Super VXO. I also had made a custom set of crystals and used a small relay to switch those into the circuit and that essentially gave me almost the full SSB Band coverage. You can see that here

 

http://www.jessystems.com/morexcvrs.html

 

Also I have been using a simple bilateral stage consisting of a 2N3906 and 2N3904 and the results have been amazing. The latest work is a follow on to my shirt pocket transceiver and uses SMD components. See attached.

 

Here are some  videos of the latest –which is now a two bander 40 and 20M. (Originally it was 75 and 40M)

https://www.youtube.com/watch?v=0UlBX7aznnM&list=UU4_ft4-oTdCMlWlL4XXHScg and https://www.youtube.com/watch?v=Wa5WiUZ9KoY

 

Have fun – this is such a wonderful hobby!

 

73’s

Pete N6QW
 

 

 

 

 

 

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

Clocks, CRTs, HV supplies: Eric has The Knack!

Nice interview by Jeri Ellsworth.  This fellow definitely seems to have the Knack.  At the end of the video he shows a high voltage supply that he is WEARING AROUND HIS NECK! 

Here's Eric's site: http://tubetime.us/


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

A Worthy Cause: Help Save the ISEE-3 Spacecraft!

http://www.rockethub.com/projects/42228-isee-3-reboot-project-by-space-college-skycorp-and-spaceref

Here is an excerpt from the above website:


Our plan is simple: we intend to contact the ISEE-3 (International Sun-Earth Explorer) spacecraft, command it to fire its engine and enter an orbit near Earth, and then resume its original mission - a mission it began in 1978. ISEE-3 was rechristened as the International Comet Explorer (ICE). If we are successful it may also still be able to chase yet another comet.

Working in collaboration with NASA we have assembled a team of engineers, programmers, and scientists - and have a large radio telescope fully capable of contacting ISEE-3.  If we are successful we intend to facilitate the sharing and interpretation of all of the new data ISEE-3 sends back via crowd sourcing.

Time is short. And this project is not without significant risks.  We need your financial help. ISEE-3 must be contacted in the next month or so and it must complete its orbit change maneuvers no later than mid-June 2014. There is excitement ahead as well: part of the maneuvers will include a flyby of the Moon at an altitude of less than 50 km.

Our team members at Morehead State University, working with AMSAT-DL in Germany, have already detected the carrier signals from both of ISEE-3's transmitters.  When the time comes, we will be using the large dish at Morehead State University to contact the spacecraft and give it commands.
Thanks to Dave, WA8JNM, for the heads up on this. 
 
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

AA1TJ Crosses the Pond with 10 milliwatts

From a Facebook Post by Mike, AA1TJ:

Made 7 contacts with this tiny transceiver on 20m CW today with an RF output power of 10milliWatts. Five were stations in Georgia (GA QSO Party). The 6th was a regular QSO with a guy in Mississippi.
I answered a DX station calling CQ at 2230Z. Hearing nothing in response, I sent my call sign a half-dozen times anyway. More silence. As I was reaching for the knob to QSY he suddenly returned my call! ...Carlos, CT1BQH northeast of Lisbon, Portugal (that's him in the second photo). I was only 329 on his end but we kept it going for three minutes!

FYI: the transmitter (top circuit board) begins with a 3.58MHz ceramic resonator VXO (a 2N706 from the early 60's). That drives a push-push frequency doubler built around another 1960's-vintage, 2N2644 (obsolete stock from atop Mt. Mansfield, kindly given to me by Rich at Vermont Public Television). On receive, the 7MHz energy is routed via a DPDT relay (the orange rectangle) to the sub-harmonic (Polyakov) mixer located on the lower board. One stage of AF amplification is provided by a 2N333 that came off the GE assembly line in November of 1958. The DPDT relay is keyed directly. On transmit the 7MHz energy feeds a second push-push frequency doubler to produce 10mW at 14MHz (all spurs -35dBc, or less, with only the output resonator). The relay also switches the antenna between the transmitter and receiver.
Gosh, that was fun!

CT1BQH

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

Bert's Pititico (PY2OHH) Rig (Video)

Bravo Bert!  

http://wf7ihomebrew.wordpress.com/2014/04/13/a-listen-on-40m-with-the-1-transistor-pititico/

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

DSB Transceiver with Only 3 Transistors

Wow.  Looks like something Peter Parker would really like.  This one was sent to me by Stephen, G7VFY.  It comes from Japan:
http://www.cqpub.co.jp/hanbai/books/15/15061/15061_p.180-181.pdf

From this book:-

http://www.cqpub.co.jp/hanbai/books/15/15061.htm

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