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!

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Long Delayed Echo on Radio China International

Several people have e-mailed me suggesting that the weird echo I have been hearing on shortwave broadcast stations is in fact one of the fabled "Long Delayed Echoes" that radio amateurs have been hearing intermittently since about 1927.   I was skeptical at first, but -- at least in the case of the Radio China signal -- I think LDE caused by the signal going around the globe several times does explain what I've heard.  Each trip would add a delay of about .133 seconds, and that seems to match what we hear in my recording:  

http://soldersmoke.blogspot.com/2014/08/strange-echo-on-china-radio.html 

Compare that with what K9FIK recorded on 10 meter SSB (thanks Stephen!): 

http://swling.com/blog/2013/10/hearing-the-speed-of-light-dx-double-echo/
(you can listen to the audio on this one). 

It sounds very similar. 

If this is in fact LDE, I'm lucky -- this is pretty rare.   And it is a eerie that I first heard it on on Regen receiver from the 1920s!  Above is a picture of the regen used to study the FIRST LDEs. See: http://folk.uio.no/sverre/LDE/


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SSB with Just Two Tubes

Here is the two tube SSB transmitter that Pete was telling me about.  This would be a nice companion to the "Mate for the Mighty Midget" receiver that I built a long time ago.  Another Benton Harbor Lunchbox may have to be sacrificed... 


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Eclectic Electronics: Powering Arduinos with Tube Filament Voltage

You know that you are dealing with a broad range of technology when you find yourself discussing how to power an Arduino microcontroller from the 12V AC voltage on a vacuum tube filament line. Thanks Pete. 

Hi Bill,

There is only so much that can be said in 1 hour and 19 minutes so maybe here is some stuff for the blog.

The 1st thing on the list when working with the Arduino when it is not connected to the computer is to have a proper power supply. My research as indicated that 9 VDC “raw” is a good starting point to power the Arduino boards so here are two supplies that will provide that power.

I did find that it was necessary to have an isolated supply when working with the “toob” radios and even to isolate the RF into the radio using a ferrite core transformer –some more tribal knowledge.

One supply takes an 8 VDC regulator and boosts its output to 9 VDC. The second uses a switching regulator and the beauty of the second is that the input can be either 12 V AC or DC. This is ideal for use in toob radios where you can sample the 12.6 VAC filament string.

73’s

Pete

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Regen Receivers in Cuba

Hola amigo Bill:

I was able to pick up the podcast with excellent audio quality.
It is quite true that regenerative receivers are very much in use
even today... for example many if not all of the automobile RF
keys opening and closing the cars doors rely on a superregenerative
receiver circuit !!!

The radio that you copied at the blog works very well indeed
but it would be  good idea to include a 5 kilo ohms volume
control.... Very easy to do indeed.

But let me tell you that my favorite regenerative receivers are
the classic ones, using vacuum tubes, and operating them
at voltages not higher than 50 volts... As a matter of fact many
tubes work very well at the 24 volts DC voltage level.
Using the classic Hartley circuit , there is no need for a hard to
find throttle capacitor required by the Armstrong circuit, because
the regeneration control works very well by using a potentiometer
to change the screen grid voltage of the detector.

I agree that using an RF stage ahead of the detector is always
a very good idea.... In my tubes regenerative I use a triode connected
6AK5 clone.... as a grounded grid stage....another 6AK5 clone ( the
6ZHE1P Russian tube ) is the detector and I use another 6AK5 clone
as the first audio amplifier then feeding an audio output pentode
all provided from a very simple basic 70 volts DC power supply.
BTW, using regulated DC on the filaments of the detector stage,
although a luxury by my standards is very helpful to reduce
hum .... 7805 regulator recycled from a bad motherboard, with
one 1N4007 from broken Compact Fluorescent Lightbulb inserted
in series with the regulator ground pin, produces a nice 5.7 volts
regulated DC that with a brand new tube is more than enough... with old
6ZHE1P recycled from Russian TV sets, you add another 1N4007 to obtain
6.4 volts regulated DC....

As said in the podcast, it is very important to do a very good
mechanical engineering job, place the main and bandspread tuning capacitors
away from the front panel, use isolated shafts between the capacitors
and the dial mechanism and make the front panel of a a thick steel
plate if possible.

There is a Dutch Cascode Regenerative radio that several Cuban radio
amateurs have built... it was designed with the amateur bands in mind so
the information about the tuning coils and capacitors lets you
obtain a very excellent bandspread on the ham bands.
I can send you that circuit that uses very common 12AT7-ECC81
and Russian equivalent double triodes.

Keep up the good work amigo and always tell us when the next
podcast is available. BTW it lasted for almost an hour !!!

73 and DX

Your amigo en La Habana, Cuba
Arnie Coro
CO2KK
Host of Dxers Unlimited radio hobby program
Radio Havana Cuba


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SolderSmoke Podcast #165 Arduinos!

SolderSmoke Podcast #165 is available: 

http://soldersmoke.com/soldersmoke165.mp3

September 13, 2014

Workbench Update:  Bill's "Off the Shelf" Regen,  Pete's Boatanchors
Mysterious Echos on Shortwave Signals.  Solve the Mystery.  Please. 
Microcontrollers -- What they can do for you.
Small world:  As a kid, Pete was neighbor of "Digital Dial" N3ZI 
NEWS FLASH: Arduino creator Massimo Banzi was a ham!  
Born in a bar, cheaper than pizza:  The Italian origins of Arduino
Arduino CW generators
No coding skills needed
Arduino + AD9850 = Signal Generator or VFO
Arduinos in the Minma
What the heck is a Shield?
SolderSmoke Mailbag

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Schematic for "Off the Shelf" Regen

NOTE (May 2024) The eagle eye of Walter  KA4KXX spotted an error in this schematic.  The source resistor in the MPF-102 stage should be around 2200 ohms.  Thanks Walter! 

Tony, VE7JUL, wrote in asking for a schematic on the "Off the Shelf" regen.  Here you go Tony.  Nothing fancy or new here.  All the credit goes to Howard Armstrong, Charles Kitchin and Jay Rusgrove! 

Even though they seem much simpler than other receivers, I think regens are in fact more of a challenge than, say, a Direct Conversion receiver.  Be prepared to do a lot of fiddling around with the coil and the tuning and regen capacitors.  Think of that detector stage as a VFO, a VFO that you want to be able to smoothly take out of oscillation. 

Here's a tip on regen debugging:  Once you have it built, hang a high impedance 'scope probe off the drain of the FET and watch the scope/counter as you move the main tuning cap and the regen control.  This will give you a visible indication of where (on the regen control) the stage is going into oscillation.  A freq counter (I have one inside my Rigol 'scope) will let you know what frequency range you are operating on.  You may end up having to make adjustments to the coil, adding or taking away turns to get into the proper frequency range, or to the desired level of feedback.  Pay attention to the phasing of the coil turns.  You may also find yourself adding capacitance in series with the regen and main tuning controls (to reduce their tuning range) or adding capacitance in parallel with the main tuning cap (to lower the entire tuning range if necessary).  

Build it solid and strong!  It is, after all, an oscillator.  Be prepared to do a lot of "noodling"   

Hi Bill,

This receiver with just 4 transistors and no chips looks really interesting to me.  Do you have a schematic that you could either flip to me or point me to?  Getting my hands on some air variable caps may be a challenge, but I can 'noodle' something out on that.

Love the podcast, blog and really enjoyed the SolderSmoke book - thanks for your continuing efforts to share with the amateur radio community.

73/72
Tony

VE7JUL

the little red dot at Coquitlam, British Columbia on what used to be the Clustr map (but is now a Revolver map)

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Shortwave Echo Mystery on Yet Another SW Station. What is this?

A few weeks ago I noticed a strange echo on Radio China International's signal.  If you scroll down a bit you can see my YouTube recording of the problem.  On one of the SWL lists, there was speculation that this problem was the result of a flaw in the RCI digital studio gear.  But then a few days ago I heard it again on RCI -- surely the tech-savvy Chinese would not have let this kind of problem persist for weeks.  

Today I heard the same effect on a very different SW station -- this one an the 24/7 fire and brimstone broadcast that appears at many points on the dial.  The effect is very similar to what I heard on RCI.  

So OK all your shortwave gurus:  What is going on here?

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"Off the Shelf" Regenerative Receiver

I call it the "Off the Shelf" Regen because the base on which it is built is scrap lumber from a recent shelf building project.  Also, all the parts came out of the junk box.  

6-10 MHz, AM, CW, SSB, Data.   4 transistors, no chips.   


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SolderSmoke Interview on ICQ Podcast

Colin and Martin of the ICQ Podcast were kind enough to invite me in for an interview.  I really enjoyed our talk.  We covered a lot of ground, everything from podcast history, to regens and BITXs and Arduinos.  I think SolderSmoke podcast listeners will enjoy this.  Thanks Martin!  Thanks Colin!  Here it is:

http://icqpodcast.com/download-the-show/2014/9/7/series-seven-episode-eighteen-bill-meara-n2cqr-07-september-2014


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Ed's Awesome Workshop

Wow, there is a lot of workshop wisdom in this video.   This is also a reminder that there are a lot of very cool people in the FDNY.   Ed is an EMT/Firefighter.  

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Arduino CW Sender by KK6FUT and N6QW

The next time Pete and I get together on SolderSmoke, we'll talk about Arduino.

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