ZL2CTM's New Zealand Double Sideband Success

New Zealand and Australia seem to produce an amazingly high percentage of the world's double sideband transceivers.  Charlie ZL2CTM adds to the count.  He took inspiration and circuitry from DSB  hams in both countries and produced this beautiful DSB transceiver.  It is obviously -- as Charlie notes -- chock full of soul.  I definitely identify with his comment about "taming some kind of  electro-mechanical machine" and also, of course, with his remark about the feelings that come with putting a homebrew rig on the air.  So follow the advice of Charlie!  Build a DSB rig and put it on the air!  Make this your ham radio resolution for 2016!  Give it a go!    

Hi Bill:

I have been following you and Pete Juliano for many years now, and thought I would send you a photo of my 40m homebrew rig that I finished yesterday. Hopefully, it will help encourage others to melt some solder and make their own rigs. The rig is based on ideas and designs from Eric Sears ZL2BMI, Peter Parker Vk3YE and of course Pete N6QW. The aim is to make the final version relatively compact so I can take it tramping/hiking here in New Zealand.

The VFO is an AD9850 being controlled by an Arduino Pro Mini. The output is amplified to provide sufficient drive for the balanced modulator. I was using a nice 1” OLED screen to show the frequency, but that generated a huge amount of noise, so I changed to a LCD. Changing frequency is simply a matter of moving the curser left and right then using the up and down buttons to change the number. Very quick and easy. I was contemplating a rotary encoder, but I find those always seem to skip and jump every now and then. Must be the way I use them...   

The balanced modulator is a 4148 diode ring. I do have some SBL-1s lying around, but I thought I’d go with the discrete diode ring for something different. I’m using a standard electret mic and a simple single stage amp. The switch above that switches between phone and CW.

The PA is two stages; the first a 2N3053 and the second a BD139. At this stage it puts out just over 1W into a 50ohm load. I might look to add another stage and get that up to 3-5W.

The audio amp is a simple LM386. I am not running it hard out as per the datasheet as it generates quite a bit of high frequency hiss in that configuration.

Unlike Pete, I don’t have access to a milling machine to make squares to mount the components on. Instead, I use vero/strip board upside down and solder directly to the strips. This works really well for me on HF. I cut tracks with the twist of a small drill bit.

Last night I made two contacts with the rig. The farthest was 527km according to some well known mapping software. Both reports said the audio was ‘very nice’, which was great to hear. The receiver worked surprisingly well too, and I managed to hear stations in Europe.

As for user controls, you will notice that the pots, switches and plugs are all over the place. I did that to keep leads short. I like it as i feel like I am taming some kind of electro-mechanical machine to generate and receive RF.

Anyway, this little rig has a ton of soul in it and is really fun to use. There is something different about making a contact with a rig you built. I really encourage everyone to give it a go!

The next iteration will be a SDR using a Teensy. Rheslip over at Open Emitter has done some great work with that.

73s

 Charlie

ZL2CTM  

Another Great DSB rig from New Zealand

So many great Double Sideband projects come from Down Under.  There are the various versions of the famed ZL2BMI rig.   And Peter Parker VK3YE has long been the acknowledged guru of DSB. In fact, Peter sent me an enthusiastic e-mail about the new ZL DSB rig pictured above -- his e-mail arrived before the message (below) from the intrepid builder.  I detect a bit of the "Tucker Tin" influence in this rig. (But perhaps this one is more Tupper than Tucker!)  Charlie's work has graced out blog posts before: http://soldersmoke.blogspot.com/search?q=zl2ctm

Be sure to check out his video:   https://youtu.be/JsAuWGkyvmE   (and below).

Hi Bill.

You asked recently on the podcast for listeners to let you know what they had on their work bench. Well I’ve been working on a tramping (hiking) radio, which is now complete. It’s a DSB 5W rig designed for 80, 40 and 20m, as well as our New Zealand mountain safety radio system. I designed everything in LTSpice as was suggested by Pete, N6QW. That was great, as I could ‘desolder’ components with the mouse and instantly see what impact it had on the output. An amazing tool that’s free! I highly recommend it.

Once again I’ve used upside down strip board for each stage, which are tacked down onto an un-etched copper board (earth plane). That seems to work really well for me.

The rig uses an Arduino mini driving a small OLED screen and a Si5351 DDS. The Si5351 is going straight into a SBL-1, which seems to work fine too. The AF strip is a 2N3904 before a LM386, which has enough drive to run a speaker. The TX amplifier is a three stage one with shielding between each stage. It’s made up of two 2N2222A stages followed by a BD139. That in turn is followed by three simple filters, one each for 80, 40 and 20m.

All-in-all it works really well. I’ve uploaded a quick video at https://youtu.be/JsAuWGkyvmE

The next project will be a proper SSB rig using a crystal filter salvaged from an old Codan 7727. Like this one, it will use an Arduino and a Si5351.

Finally, I am certainly no expert in homebrew, but I hope my ‘dabbling’ will help inspire others to pick up the soldering iron and give it a go. If I can do it, then anybody can! There is certainly a great sense of achievement to operate a rig you built yourself.

Regards, and thanks to you and Pete for all your inspiration.

73’s

Charlie

ZL2CTM

A Double Sideband Transmitter from France -- F4IET's "Master Robert"

The Radio Gods seem to be steering us toward Double Sideband.  A few days ago I got an e-mail from Alain F4IET.   We had him on the SolderSmoke blog two years ago, talking about his French backyard pandemic Field Day.  His recent e-mail reminded me of his very fine homebrew DSB transmitter, which is his only rig and with which he has worked the world. 

The rig is named for the fellow -- Robert F6EUZ -- who is Alain's teacher from the local radio club. 

Alain's rig was shown to the world in the G-QRP club's Winter 2020 issue of SPRAT (SPRAT 185).  Once again, let me note:  If you are not subscribing to SPRAT, you are just WRONG.  Join G-QRP and start receiving SPRAT:  http://www.gqrp.com/join.htm

Alain gives some nice shout-outs to Pete N6QW,  Charlie ZL2CTM, and Basanta VU2NIL, all of whom provided advice and counsel on this project.  So think about it:  the Master Robert rig was built in France under the guidance of a French Elmer, with advice from hams in the U.S., New Zealand, and India, and was featured in journal of the British QRP club.  That, my friends is the International Brotherhood at its best. 

As I read about Alain's rig, I found myself thinking about the Direct Conversion receiver projects underway around the world.   The Vienna Wireless Society's Maker Group, is, for example, building a simple DC receiver.   It would be relatively easy to pair up a rig like the Master Robert with a DC receiver (the VFO could be the only stage common to both transmit and receive) to make a simple phone transceiver.  That kind of rig was my first phone transceiver.  Alain reports that he is currently working on a second version of the Master Robert.  It will be a transmitter-receiver (TRX) and will be used in SOTA operations. 

Alain's description of his transmitter is a lot of fun: http://www.f4iet.fr/mdwiki/#!master_robert.md

I especially liked his comment about how the other phone stations never knew he was on DSB: http://www.f4iet.fr/mdwiki/#!dsb.md I had similar experiences out in the Azores with my DSB rigs.  

Here is Alain's main page: http://www.f4iet.fr/mdwiki/#!index.md

Alain's QRZ.com page:  https://www.qrz.com/db/F4IET

Here is the Master Robert schematic from GQRP: http://www.gqrp.com/Maestro_Robert_Cct.pdf

 

Here is a link to the 76 DSB posts on the SolderSmoke blog (keep scrolling down!): 

https://soldersmoke.blogspot.com/search/label/DSB

Charlie ZL2CTM's New Receiver

It is truly a thing of beauty.  

I really like that variable capacitor.  (Where did that come from?  How can I get one?)   

Charlie's calculations on each of the stages is -- as always -- really nice.  

I like the J-310 infinite impedance detector,  Charlie's use of solder wick,  the wooden base, and his decision to keep the circuitry visible.   

I also like Charlie's decision NOT to put that VFO in a metal box.  Too often we see projects that try to convince us that the receiver just won't work unless everything is hermetically sealed in submarine-like boxes.  Not true!  And Charlie's receiver demonstates this.   

Charlie is clearly keeping up the Kiwi tradition of fine homebrewing exemplified by the Tucker Tin 2,  ZL2BMI's DSB rig,  and many other FB HB projects from ZL. https://soldersmoke.blogspot.com/search?q=New+Zealand+DSB

Thanks Charlie!  Be sure to check out the rest of his YouTube channel: https://www.youtube.com/@CharlieMorrisZL2CTM

Kiwi Lunchbox Sideband: The Tucker Tin Two

Pete Eaton sent us links to an old article from the New Zealand magazine "Break-In."   So many good, simple rigs come to us from New Zealand!  Who can forget ZL2BMI's DSB rig?  This one is the work of Fred Johnson ZL2AMJ.  It is especially interesting and is in some ways similar to Peter Parker's "Knobless Wonder."

It uses the phasing method of sideband generation.  No crystal filters in this one.  You need TWO balanced modulators.  You have a 90 degree phase shift network for the RF (from the carrier oscillator) and a second 90 degree phase shift network for the AF from the mic amplifier.  When you combine the signals from the two balanced modulators -- viola! -- one of the sidebands disappears.  The balanced modulators take care of the carrier, and an SSB signal is launched.  That is how my old HT-37 works, and similar ideas seem to be at work in modern SDR rigs.  

G3TXQ has the complete set of Break-In articles (it includes a VFO): 
http://www.karinya.net/g3txq/temp/tucker_tin/   

Here is a Canadian article on the rig.   A "Tucker Tin" is apparently what the Kiwis call a lunch boxes (shades of Benton Harbor...).  

Thanks Pete!

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

An Old but Cool DiFX: The Epiphyte

I've been hearing about this rig for many years.   It first appeared in the September 1994 issue of QRPp, the journal of the NORCAL QRP club. A condensed version of that article appeared in SPRAT 81 (Winter 94-95). The designer is Derry Spittle VE7QK from Vancouver, British Columbia.

The name always puzzled me.  Here is the explanation:  It started with the Neophyte: A very simple direct conversion receiver that many of us built.  The Neophyte was mostly an NE602 and an LM386.  In the Epiphyte, a crystal filter and a second NE602 were added, turning the Neophytes into a superhet receiver and -- with some additional circuitry -- an SSB transceiver.  The Oxford English Dictionary reportedly defines an Epiphyte as "a plant that grows on another plant"(see picture below).   The Epiphyte grew out of the Neophyte.

And this plant grew in British Columbia, which seems -- like Australia and New Zealand -- to be fertile ground for simple phone rigs.  I'm pretty sure the "Wee Willy" DSB rig also came out of BC, and it may have had a similar purpose:   allowing for portable contact with the BC Public Service Net on 75 Meters.  

There are many features of the Epiphyte that I like:  There is a simple 455 kHz filter and a ceramic resonator BFO/Carrier oscillator. The original design featured a VXO-like circuit using a ceramic resonator at 4.19 MHz.  And it ran off AA batteries (as did the NE602 DSB rig I took to the Dominican Republic).

Unlike my NE602 rig, the Epiphyte made an artful use of the fact that NE602's can be set up to have TWO inputs and TWO outputs.  Where I used DPDT relays to switch inputs and outputs from both NE602s,  OM Spittle left all the inputs and outputs connected, and simply switched the VFO and BFO signals.  Ingenious.  

There were updates and improvements.  The Epiphyte 2 and 3 featured increased power out (5 watts vs. 1 Watt).  Version 3 has an IRF-510 in the final, driven by a CA3020A chip.  That chip is capable of 70 db gain.  Wow. 

In 1996 NORCAL and G-QRP donated 50 EP-2 kits to radio amateurs in third world countries. Very nice.

In 2000 NORCAL did a kit of the EP-3 -- it sold out in 24 hours.  Here is a nice article on the EP-3:
http://www.norcalqrp.org/files/Epiphyte3Mnl.pdf

And above we have a video from Japan of an EP-3 in action.