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  

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

The ZL2BMI DSB Transceiver

Oh man, I've been a fan of this rig for many years. I first read about it in the pages of SPRAT. Today I stumbled across what appears to be an on-line version of the instruction booklet prepared by Eric Sears, ZL2BMI. Lots of lore in there. Lots of soul in this rig.

This site has three documents describing the rig. All three are a lot of fun: http://www.mightymessage.com/

Three cheers for Eric Sears! Hip-hip...


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

SolderSmoke Podcast #134

http://soldersmoke.com/soldersmoke134.mp3

May 15, 2011
New "Ikea" microphone
NOVA QRP Club
WSPR T/Rouble resolved
Finishing up Rome WSPR rig
Easy-Peasy on Asus eee-PC
Space Station Packet Beacon
Boatanchor News: DX-100, HT-37, "CQR" anchors, 75 meter antenna Drake 2-B history interview by W8SX
Lew McCoy and Ernest Hemingway
Ade Weiss, QRPoetry and Ade's new book
Regen theory
MAILBAG (with a focus on New Zealand)

80 milliwatts to New Zealand (and Italy)

I realize that having your QRSS signal show up on a distant grabber is no big deal, but this was the first time I've seen the signal from my little DaVinci Code rig make the trip to ZL. You can see my shark fins in the screen shot above. It was just before dawn here, so gray line must have been helping. A Solar Flux Index of 92 also helped. My shark also made it across the Atlantic (and half the Med!) Mauro IK1WVQ's grabber made this nice capture (looks like this was around dawn at his location):

I measured the voltage at the antenna terminal this morning. Less than 2 volts peak. Assuming a 50 ohm load, that's about 80 milliwatts. This is all especially gratifying because yesterday I was out in the backyard with a slingshot and a fishing reel, putting a bit more wire into the trees. It worked!

Here's the transmitter and the schematic. FSK is from a simple two transistor multi-vibrator (G0UPL's circuit -- you can see it in the lower left):

Minimalist Computing from New Zealand

My Toshiba Satellite Pro 400CS went toes up in 2006 after many years of service. It died with a horrible grinding sound from the hard disc. I tried to bring it back to life, and bought a replacement HD, but I never could get it going and the project got sidetracked... until an e-mail from Kevin, ZL3KE, (see below) got me back in the old computer repair business.

With long-distance help from Kevin I
1) Got a boot-able DOS disc, which got me to an A:
2) Partitioned and formatted my HD which got me a C:
3) Loaded DOS drivers for my CD ROM drive which got me a D:
4) Used the CD-ROM drive to load Windows 3.1 which really brought this thing back to life.

I usually dislike working on computers, but with Kevin's help and encouragement, this project was fun. And I can now use some old programs that I haven't been able to use since the advent of Windows 95, like my favorite astronomy program "Distant Suns." I'm also running ON7YD's excellent QRSS transmit program.

I always liked the audio features of this computer. With a bit of driver downloading, I now have sound. There are some nice audio clip files in this (birds chirping, machine guns, another gong!)
that may find their way into the podcast.

Any thoughts on what else I can do with this machine? Any other Windows 3.1 applications?

Here's the message from Kevin that re-started all this:

Minimalist/QRP computing

Friday, March 6, 2009 1:09 PM

From:

"Kevin Ravenhill"

To: soldersmoke

Hi again Bill,

I was amused to hear your comments about QRSS and the ever-so-slight
discrepancy between the number of transistors needed for Rx and Tx...

Maybe it's time to introduce the concept of the "QRP Computer" - using
older/slower hardware generally regarded as obsolete, but otherwise
perfectly serviceable and having a much smaller carbon footprint than the
latest 2.5GHz+ machines! This is something which I've been working towards
for some time.

I'm typing this on an old 233MHz Pentium laptop (Toshiba Satellite Pro
480CDT), with 64MB of RAM, a 3.8GB hard disk and an 800x600 screen,
running a cut-down version of Win98SE with all web integration (IE etc.)
stripped out. This will happily run pretty much all the radio software I
need without complaint (such as MMTTY for RTTY, MMSSTV for SSTV, Digipan
for PSK31, Argo, Spectran, IZ8BLY Hellschreiber, WSJT v4, etc).
Just about the only thing lacking is WSPR, which I would very much like to
run but I think it probably needs more resources than this machine has
(Joe Taylor, are you listening? ;-).

The rationale was/is to find the simplest, smallest, most bloat-free
programs to accomplish what is needed (minimalist computing, in other
words) - and it must all be freeware or similar - bells & whistles are
frowned upon, and definitely no commercial stuff allowed! I wouldn't say
I'm 100% there yet, but the journey so far has been interesting and
rewarding.

Although this was originally intended to be a dedicated machine for radio,
I now find myself increasingly using it for things like web-browsing and
email as I find the whole "no bells & whistles" experience quite
refreshing (I use Popcorn email and a minimalist, no-javascript browser
called "OffByOne" - my browsing needs tend to be fairly basic and I tend
to regard any website which uses Java/Flash etc. as not worth the effort).

I think Mike AA1TJ's quote on his "Reggie" page is quite apt here: "In
anything at all, perfection is finally attained not when there is no
longer anything to add, but when there is no longer anything to take
away...."

72/3, Kevin
ZL3KE