New Rigs but Old Mics

http://www.cbgazette.com/history_tommoss-turner.html

So now I have THREE BITX transceivers on the operating bench.  I've been getting tired of moving the old D-104 around as I change bands.  Surely each of these rigs merits its own mic.  This would allow me to avoid the hassle of having to adjust the level on the D-104 each time I change rigs.

Fortunately in the junk box I have some useable old mics.   An old "Turner SSB+2" mic  has been kicking around in there for decades.  I probably got it when I was a kid. The element was no longer working, so I just popped an electret element in there, took out the preamp circuit, but kept the adjustment pot.  At first I had a 3.3 uF coupling cap in there at the output, but this was letting too much 300 Hz energy through.   So I changed the coupling cap to .1 uF and this seemed to even things out a bit. 

I know, I know: It is CB gear.  It is painted BLUE and it looks like something George Jetson would use to talk to his interstellar Good Buddies. But it was preceded by a very similar mic made for hams (see above).   And I like it.  It even has the word "Transistorized" emblazoned in script across the PTT bar. 

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The Truly Amazing Workbench and Shack of VE7ZWZ (Video)

Brace yourselves.  This is almost too much.  Prepare for sensory overload and possible palpitations.
 
Wow.  This is really amazing.   Note the very casual way Paul manages to mix Eico 430 oscilloscopes with the latest Tek touch-screen 'scope.  Heck, the doesn't even mention the SP-600s!  He does briefly note "a very large transmitter." Indeed. And he has a microscope on the bench.

This video is part of an excellent YouTube channel called "Mr. Carlson's Lab."   Great stuff in there.  Paul works on everything from old tube type receivers to modern Yaesus and Icoms.

It took me a little digging to find his ham radio call sign.  There are many Paul Carlsons on QRZ.com, but Paul's pronunciation of "solder" gave him away.  It seems our Canadian friends also (like the Brits) pronounce the "L."  VE7ZWZ. 

Check out his channel.   Lots to learn there:   

https://www.youtube.com/watch?v=qqmegXoB7lA

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Armand's Bench (and Hamfest Goodies)

 

Above is the workbench of esteemed long-time SolderSmoke listener and electronic wizard Armand WA1UQO.  Lot of good stuff on that bench. 

 

Armand made it to the recent Manassas (Virginia) hamfest.   Here is what he came back with. 

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A Homebrew Compendium from Hungary

Stefano IZ3NVR sent me HA5KHC's very interesting web site.   Lots of ideas here. 

For example, check out WA7JHZ's 75 meter SSB transceiver.

http://konstruktor.ha5khc.hu/linkgyujtemeny/linkgyujtemeny.htm

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Video of Pete's VERY COOL Zia Build

This is cool in so many ways:

I like the RF amp along the back with the LP filter off to the side.

The stacked PC boards are very nice.

The Display -- What can I say?

Having stations from the Philippines (DU) for the receiver demo.  Nice touch.

Mesh-like side panels!  And the plexiglass top!  Wow!

PAINTING THE COPPER-CLAD FRONT PANEL BLACK!  WOW!  BLACK IS THE NEW COPPER!

Nice feet for the rig.  Feet are key.

NO NOTICEABLE PHASE NOISE.  No Si5351 output bleed-over.

Love the name:  ZIA!!  (That was my only contribution.)

Back with the Sats: Catching Cubes with a Dongle

I've been playing around with a little $13 DVB-T SDR Dongle receiver.  These devices normally tune 24 MHz to 1.7 GHz, but I modified the first one I had so that it would tune the HF bands.   Pete then sent me another one, which I vowed to keep unmodified, thinking that it would be fun to use it to listen to the many small Cube-Sats that are up there.  Most have downlinks (and Morse Code beacons) in the 470 MHz range.   I whipped together a simple ground-plane antenna for this band (One 6 inch copper wire as the receive element with 4 five inch groundplane elements). 

 

I then went to the "Heavens Above" website, plugged in my location, and clicked on "Amateur satellites."  This gave me a very accurate schedule of satellite passes.  I started listening. 





First I heard (and saw in the HDSDR waterfall)  the CW beacon of the Prism satellite at 7:05 am EDT today.  Prism is from the University of Tokyo and was launched from Japan.

Then Cubesat XI-V at 0711 EDT.

Cubesat XI-IV was heard at 0813 EDT.  The Cubesats are from Japan and were launched from Russia.  

ITUsPAT was heard at 1422 EDT.  The I is for "Istanbul"

Finally,  I monitored a pass of the Japanese FO-29 satellite aka JAS-2 at 1611.  Wow, this was like old times on the RS-10 and RS-12 satellites.   Lots of CW and SSB stations in the downlink passband.   Lots of fun.

At 470 MHz the Doppler shift of a low-earth orbit satellite is quite noticeable, and helps confirm that you are in fact receiving sigs from an orbiting device.

I thought it was pretty cool to take a $13 DVB-T Dongle, connect it to a small, copper-wire antenna, and use it all to receive signals from some 4"x4"x4" cubes in orbit of the Earth.

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Pete Puts His Zia in a Box

 

Wow, Pete really knows how to pack a lot electronics into a small box.  (He claims that he does this to justify the $250000 CNC machine!) I remain very jealous of that cool display panel. 

  

 

  

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Why "Q" for Transistors?

Steve Silverman provides a possible answer:

"There are claims that, after initial chaos, eventually the letter Q was chosen because of the popular TO18/TO39 case styles."

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Another Great Rig (and Video) from Peter Parker VK3YE

Peter Parker has a double dose of The Knack:  Not only is he a great rig builder, but he is also a very skilled teacher.  His videos provide really excellent descriptions of how he selects, designs, and modifies the stages that make up his magnificent rigs.  You can learn a lot from these videos.  Thanks Peter.  

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Why are relays marked "K" on schematics?

Our official SolderSmoke etymologist and lexicographer Steve Silverman explains:

Bill

    Here is some ham radio/electronics trivia

    In the days when amateur radio used short range spark transmitters, multi-station relays were used to move a message across longer distances.  At the end of each transmission, a "K" was sent, which told the receiving operator to commence his relay to the next station. Hence the use of 'K" to designate a relay in a schematic diagram, and "end-of-transmission" for CW operators.  And hence the American Radio RELAY League

73Steve Silverman

KB3SII  ... .. ..

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Progress on Pete's "ZIA"

It is practically SPARKLING!   Beautiful job Pete.  I'm glad you are actually boxing this one up! 

Pete has many more pictures of this project here: 
http://www.n6qw.com/TIA.html

He also notes that there may have been some sub-conscious Knack wisdom at work when I dubbed his rig "The Zia."   I was thinking strictly in terms of language and ethnic heritage:  TIA stands for Termination Insensitive Amplifier.  But in Spanish it means "aunt".  But in Italian Aunt comes out as Zia.  So Pete's should be a Zia, right?  Capisce?

Well Pete puts an electronic twist on it:

"Once again you are spot on with ZIA (With  Z the electronic symbol for Impedance).  Thus Impedance (The symbol Z) Insensitive Amp. Thank You."

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20% off Sale on "SolderSmoke" and "Us and Them" Books at Lulu

20% off on all print books at Lulu through June 18:

 

http://www.lulu.com/spotlight/soldersmoke  

 

Use coupon code SPLURGE

 

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Finally! An Award for QRP DSB! VK3YE's 40-40 Award

Brilliant!   Great stuff!  Lots of fun! 
Another great idea from Peter Parker, VK3YE.

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SolderSmoke Podcast 177 Bicoastal Termination Insensitivity Unphased by Phase Noise

 

SolderSmoke Podcast #177 is available:

 

http://soldersmoke.com/soldersmoke177.mp3

 

13 June 2015

 

-- PETE JULIANO INDUCTED INTO THE QRP HALL OF FAME

-- Bench Reports:  Bicoastal Bilateral Success:  A Tale of Two Tias

    Only 3 TIA rigs in the world?  It depends...

    Relay improvements in the BITX Builds

    Straightening out amp problems

    The many uses of copper foil

    No phase noise or bleed-over troubles

    Plug-in filters

    Adjusting TIA amp gain on RX and TX (too much is not good!)

    Getting the BITX to work with the CCI amp

    Allison wisely prescribes 3 db pads 

    Curing hum by moving the power supply (duh!)

-- Farhan's New Minima -- Crying out for an Si5351?

-- Mike KL7R's Web Site is Back (thanks to W8NSA)

-- SolderLex: Rigs or Radios?  We go with Rigs

-- A ham rite of passage:  Build a Dipole!

-- What does your shack look like at the end of a project?

-- MAILBAG 

    The CORRECT pronunciation of Belthorn

    Multiplication and Division by 4

    W8NSA, Vietnam, a Transoceanic and a 9V Battery 



 

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Termination Insensitivity -- Only Three TIAs in the World?

Termination Insensitivity.  Is this like when your girlfriend dumps you and you just don't care? 

No. It's more like this:

http://www.n6qw.com/TIA.html

Wes Hayward and Bob Kopski developed the Termination Insensitive Amplifier circuit back in 2009.  With a bidirectional rig it is important that the crystal filter face the same impedance in both directions.  Simpler bidirectional amps are impedance "transparent" in that their input impedance depends on what is on the output (and vice versa).  The circuit that Wes and Bob developed solved this problem:  these amps always look like 50 ohms.  That's very useful.  When I was building my earlier BITX rigs, Farhan suggested that I try the termination insensitive amp circuits.  On my latest project I followed his suggestion.  At the same time, Pete was building a new BITX, also using the TIA amps. 

Pete wrote to Wes and Bob and asked if anyone had followed through on their 2009 article by building a rig using this circuit.  Wes said that he was unaware of any TIA rigs.  It turned out that Tom Hall up in New York City had built one (video below). So I guess Pete's rig is TIA 2 and mine is TIA 3!  (But I was thinking, because of Pete's Italian ancestry, shouldn't we call his rig a Zia?)
Please let us know if you know of any other TIAS (or ZIAS!) out there.

Here is Tom Hall's very FB TIA:



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BITX DIGI-TIA Build Update #7: On The Air!

 

With lots of encouragement from Pete, I finally got the BITX DIGI-TIA on the air.  The first contacts were made yesterday. I have it on 40 meter SSB.  The finicky denizens of that audio-conscious band seemed to like the sound of the rig.   I was almost reluctant to tell them it is homebrew (no need to stir up trouble!)

 

The plug in filter arrangement seems to work very well.  This will allow me to put this rig on many other bands.  All I have to do is build some additional filter boards and upload modified versions of the software.  There is even space to make a plug-on socket for the crystal filter (the 9 MHz IF would not be cool for 17 meters).  

 

I'm really pleased with the RF power chain (the original BITX chain).  This time I built it all in a straight line along the back of the transceiver with lots of attention to shielding and grounding.  There were no instability problems.  The amplifiers did not try to be oscillators.  I was shocked!

 

I did have to reduce the gain of the three termination insensitive transmit amplifiers. Using the chart in the 2009 Wes Hayward/Bob Kopski article,  with just a few resistors you can set the gain.   I had built them with 19.4 db gain each.  This turned out to be too much -- the slightest amount of audio into the SBL-1 was driving the amplifiers to peak output.  So yesterday I changed all three amps to 15 db (I think that was what Farhan had in the original BITX).  It only took me about 15 minutes and it seemed to take care of the problem.  I am getting 7 or 8 watts out of the IRF-510.

 

T/R switching is very smooth and quiet using just two small 12V relays.

 

Thanks to Pete for the mil-pad boards and the encouragement (especially on the use of the Si5351).  Thanks to Farhan for the BITX architecture. Thanks to Steve Smith for the Yaesu filter.  Thanks to Wes and Bob for the TIA circuit.  Thanks to Thomas in Norway for the Si5351 software.  And Thanks to Allison for all the good advice.



 

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Moonbounce, Meteors and French Radar in Scotland

David GM4JJJ was the fellow who sent us the video of early Scottish moonbounce ops.  This morning he sent me a tale of woe involving some transverters and several BASTA! moments.  I will spare you all the painful details, but I really liked this paragraph about David's use of sigs from a French space surveillance radar:  

... While the transverter for 144 MHz was being tested out into my new homebuilt antenna I tried receiving the French space surveillance GRAVES RADAR on 143.050 MHz. It is easily detected here in Scotland via meteor scatter. It is also so strong that passing space hardware like the ISS reflect the RADAR and can also be detected, showing up on FFT displays with their rapid Doppler shift.  GRAVES is also easily detected by moonbounce, I could see it and hear it on my single 10 element yagi pointed at the horizon without a preamp. Even when the moon was at 15 degrees elevation here, and even higher in France the signal was strong enough to be picked up in one of the lobes of my antenna. You can actually see what the vertical pattern of the antenna looks like as the moon rises through the peaks and nulls of the antenna in conjunction with the constructive and destructive interference patterns caused by ground reflections and the direct path to the moon.

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Rigs vs. Radios: A Real RIG in a Real SHACK

Earlier this year Pete and I were talking about the use of the word "rig."  For me this is a hallowed term that captures much of the essence of ham radio.  Sadly, in modern parlance "rig" seems to be increasingly substituted by word "radio." If you are wondering what the difference is, well, I think this video presents a good example of a rig. 

There was a nice exchange of e-mails on QRP-L about this video: 

Jun 2 at 9:54 PM

Hi Bill.
I've operated a breadboard rig just to watch the electrons move thru the circuits but never worked such a kluged station yet.
73 de Ed, K1RID
(formerly KC1BBC)

 On Jun 2, 2015, at 21:30, Bill Cromwell wrote:
 Hi Ed,
I worked some lashups like Mike's. I still do. Once upon a time I "temporarily" taped a T-R relay under a shelf and used it temporarily enough months for it to come untaped and fall in the middle of a QSO! I finished the QSO anyway. I don't tape relays to the bottom of shelves any more but the top of the shelf is fair game. No relay ever fell *up*. I've worked Mike on the air. We have some of the same views.
  73,
  Bill  KU8H

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Mike Caughran (KL7R) Web Site

The links recently went bad, but fortunately Jim W8NSA saved the old site (most of it).  Thanks Jim.

http://www.commcenter-8.net/kl7r/


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BITX DIGI-TIA Build Update #6: Boxing it up!

 

Basic Basswood Box (From Michael's or Amazon)

 

Space cut out for Si5351 board and for AF Gain and Mic jack

 

Copper flashing placed (from Home Depot)

 

Amplifier Chain placed along the back

 

 

Note Plug-In Low Pass Filter

 

Starting to look Rig-ish

 

The View from Above

 

Still to do:

 

Socketry along the back (Antenna, 12V, external amp T/R control, Speaker, MAYBE:  IF connection).

 

 

Relay wiring (I'm trying to do this with just 2 DPDT relays: one for Low Pass Filter switching and External Amp T/R control,  and one for 12V T/R switching, and Bandpass Filter switching.

 

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BITX DIGI-TIA Update #5: Amplifiers Built and Tested

I have the RF amplifier stages done, and I worked a bit on the shielding.  This circuit board will be along the back, turned around, with the copper-clad shields between the amps and the rest of the rig.  In the picture you can see the small inter-stage shields, and one that put between input and output on the final.  All this in the probably vain hope of avoiding the Agony of Oscillation.   We'll see.  So far so good.  I get about 8 watts out of the IRF510 on 40 meters.  53db total gain for the three stages.  Of course, all this will likely change once the rest of the rig, the LP filter and an actual antenna are added.

 

As for the mic amp problems I mentioned last time, well,  I discovered on earlier BITX projects that one of the resistors in the base circuit needs to be changed from 10K to 39K.  It is kind of a long story (maybe for the podcast) but essentially I had to discover this AGAIN.  More details here:

http://soldersmoke.blogspot.com/2013/10/bitx-build-update-15-necessary-mic-amp.html 

 

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BITX DIGI-TIA Update #4

 

Lots of progress over the long weekend.  Along the back you can see the three stages of the RF amplifier chain:  2N3904, 2N2218A, IRF510. I intend to add inter-stage shielding, and one long shield between the chain and the rest of the rig.   Front and center is the Si5351 board (code by LA3PNA).  Mic amp (which gave me a lot of trouble!) is to the right of the Si5351.   AF (RX) amp is to the left (2N3904 and LM386).  The big board in the center has the three Termination Insensitive Amplifiers (thanks Wes and Bob), the 9 MHz filter (thanks Steve Smith!) and the two SBL-1 mixers (thanks to Pete Juliano for the "mil-pad " boards).  And thanks to Farhan for the overall BITX concept and the TIA suggestion.  

 

In the upper right you will see where the plug-in low-pass filter will plug in (a better picture appears below).   I will use a similar plug-in for the band-pass filter.   Combined with the BFO/VFO flexibility of the Si5351, this plug in feature should allow me to cover many bands with this rig.    

 

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Sage Advice on Homebrewing from WA3EIB

Bill, Pete,
 
Thanks for the sage advice.
 
You are absolutely right, I should stick to the plan and finish the project before tromping off in a different direction.
Anytime I've ever changed designs before I have completed a task, usually results in something far less than expected.
 
The real joy is completing a project and looking back at what was accomplished.
 
My own personal goals for the Minima Transceiver Construction include...
 
1. Build it from SCRATCH - Manhattan Style.
2. Start with modular construction - so that each circuit can be tested, troubleshot and modified in the future.
3. SMA connectors and coax to every stage so, I can divide and conquer the function of all modules.
4. Document the entire journey so I can actually see where my learning's took me.
5. Provide myself, a basic building block for future transceiver construction and designs.
6. Improve my skills, techniques and knowledge through my mistakes and understandings. 
7. Learn to SLOW DOWN, study, plan and write, in my own words, what the circuit(s) do and how they function.
8. Be a mentor to others and share what I have learned.
9. Be more of an Amateur Radio Experimenter and less of a Ham Radio Operator.
10. Continue to dream and design.
 
Each day should be NEW and EXCITING. There should be a thrill in every step of the way, even in the midst of failures.
 
Thank you both for taking the time to respond.
Thanks for the encouragement and sharing what happens on your own bench.
 
73's
 
Harv -=WA3EIB=-

---------------------

More inspiration from Harv here:
http://soldersmoke.blogspot.com/2012/09/an-ode-to-old-time-radio-by-wa3eib.html

And here:

http://soldersmoke.blogspot.com/search?q=WA3EIB

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Frank Harris and the Nobel Prize for Sideband

A lot of wisdom and good info in this chapter (and in the whole book);

http://www.qrparci.org/wa0itp/chap15.pdf

http://www.wa0itp.com/crystalsetsssb.html

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National RF

 

Pete and I both spotted the ads in QST for this company and their little HF receiver.  In the finest tradition of Tuna Tins and Herring Aids, that receiver is in a SPAM can.   FB. 

 

http://nationalrf.com/75_NS-3.htm

 

I visited the company's web site this morning.  Lots of great stuff!   They are based in San Diego.  Who are the radio wizards behind this effort? 

  

http://nationalrf.com/products.htm

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BITX DIGI-TIA Build Update #3 Video of Receiver in Operation

A few things I forgot to mention in the video:

That USB port on the front panel has already come in handy.  I needed to switch the tuning increment from 1 kHz to 100 Hz.   I just went into the Arduino program, removed one zero, and then re-uploaded the code.  

I also put to use the sideband inversion rule-of-thumb:  My IF is at 9 MHz.  I want to receive signals in the 7.2 MHz range, and I want the VFO running ABOVE the IF frequency.  So obviously the VFO will be running at around 16.2 MHz.  So, rule-of-thumb time:  Will I be subtracting the frequency with modulation from the frequency without modulation?  Yes I will!  So, there will be sideband inversion.  This tells me where to position my BFO frequency.   The signals on 40 start out as Lower Sideband.  But as explained above, by the time they get to the filter they will be inverted and will be upper sideband signals.  So I need to put the BFO slightly BELOW the filter passband so that I can tune the signals in such a way as the sidebands fit into the filter passband and have the proper frequency relationship to the BFO to allow for demodulation. I put it at 8.9986 MHz.  With the Si5351, changes to the BFO and VFO frequencies are very easy.

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Pete Juliano, N6QW, Inducted into the QRP Hall of Fame

Reliable sources in Dayton, Ohio and in the United Kingdom report that Pete Juliano, N6QW, has been inducted into the

QRP Hall of Fame. 

Wow, that's great news! 

Richly deserved! 

Congratulations Pete!

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SolderSmoke Podcast 176: Knack-Related Conditions: Termination Insensitivity, Sideband Inversion, Dongle Modification, Area 5351 Conspiracy Disorder

SolderSmoke Podcast #176 is available! (And it is GOOD!)

http://soldersmoke.com/soldersmoke176.mp3

16 May 2015

Bench Update:
Pete releases some magic (amplifier) smoke
Pete's new termination-insensitive transceiver makes first contact
Bill goes Yaesu (well, just a filter)
Juliano Mill-Pad boards
Termination Insensitivity is not a personality disorder!
Flip those Bilat Boards!  Pete's cool technique for bilat building
Bill's project notebook and stage testing
Installing the W6JFR EMRFD SBL-1 Bal-Mod Mod

AREA 5351:  Myths, Urban Legends, and Conspiracy Theories about the Si5351

A Rule of Thumb for Sideband Inversion

Dongle Madness and the Dangers of Dongle Modification
What is a dongle?
24 Mhz to 1.7 GHz right out of the box
Modification for 0-29 MHz
Tapping the IF of a Drake 2-B
Getting another one for VHF-UHF
Dongling Meteors, Satellites and Airplanes

SPRAT cover AD9850 in 1988!  Three cheers for SPRAT (and QQ and QST).

Elecraft's new Rig

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BITX DIGI-TIA Build Update #2 Installing and Testing Yaesu SSB Filter

Termination Insensitivity.  It sounds like some sort of psychological problem, but it is not!

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BITX DIGI-TIA Build Update #1 Building the First 2 TIA Amplifiers

I started building the new transceiver today.   I am tentatively calling it the BITX DIGI-TIA.  Digi because it will have at its heart an Si5351 for BFO and VFO signal generation, and TIA because it will use Termination Insensitive Amplifiers (TIAs).  These TIA amps are designed to present a 50 ohm impedance not matter what impedance you connect to the other end.  This is a very useful feature when you are trying to get a certain impedance for a crystal filter in a bidirectional rig -- you want the same termination impedances in  both directions.

 

I built the "top" halves of two of the TIAs, using CNC-cut boards given to me by Pete Juliano.  Thanks Pete!  I like the boards, and I no longer have a thick coating of dried SuperGlue on my fingers.

 

Both amps seem to be performing  very well. Some numbers:

 

Current draw at 12 V (no signal) 30 ma.

 

Gain at 9 MHz (no load):  Amp 1:  27.2 db    Amp 2: 26.5 db.

 

I then took a 110 ohm load and put it across the output of Amp 1.  Gain dropped to 23.9 db (as you'd expect).  BUT HERE'S THE GOOD PART:  The input voltage from my homebrew sig generator stayed exactly the same.    Termination insensitivity. 

 

More on these amps (with a link to Wes's article) here:

 

http://soldersmoke.blogspot.com/2015/04/termination-insensitive-bitx-amps.html 

 

Next  I'll put the 9 MHz filter between these amps and measure the shape of the filter passband.

 



 

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IF Selection -- Which Filter for the New Rig?

With some prodding from Pete Juliano, I am moving forward on my next transceiver.  Same wood box enclosure (with copper flashing), but this time I am greatly relaxing some of the radical fundamentalist restrictions:  Chips will be allowed. VFOs and VXOs will be replaced by an Si5351. Filters will not have to be homebrew.  Pete has been putting his CNC machine to use and making me some nice boards with isolation pads already milled in.  Oh, the luxury!

I am going to use the Termination Insensitive Amplifiers designed by Wes Hayward and Bob Kopski back in 2009.  These are especially useful in bilateral type transceivers because they allow you to nail down the termination impedances on the crystal filter IN BOTH DIRECTIONS.   That's is important if you want the same filter shape on both transmit and receive.

But now, with the trauma of my unfortunate IF selection on the BITX 20/40 (now just 20, sniff...) in mind,  what filter should I use on this rig?  The three main candidates appear above.   The 9 MHz Yaesu filter was given to me some time ago by Steve "Snort Rosin" Smith.   The Heath filter (3.395 MHz) and the larger silver one (2.215 MHz) were given to me by Armand Hamel. (Thanks Guys!)

My main band of interest for this rig is 40.   But if possible, I'd like to be able to use it on 15 and 12 meters,  and maybe even 20 and 17,  hopefully without having to change filters. 

 So what say the gurus?  Which one should I use?   Or should I put two of them in there, with provisions that would make it easy for me to move from one to the other? 

Right now my inclination is to go with the 9 MHz filter, perhaps with the 3.395 MHz filter also available.


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Sideband Inversion

Joel Hallas, W1ZR, (aka "The Doctor") has an especially good column in QST this month.   He takes on a topic that has confused (and re-confused!) many of us: sideband inversion.  Simply put, if you have a single sideband signal, and you put it through a mixer, depending on the frequencies involved and on whether you take the sum or the difference product of the mixer,  the sideband may or may not get INVERTED!   You could start out with an UPPER sideband signal coming out of your sideband generator, then, after you mix it with your VFO (or Si5351!) you end up with a LOWER sideband signal.  This can be quite an unpleasant surprise.

Joel gives us a good rule for remembering when this will happen: 

"Sideband reversal occurs in mixing only  if the signal with the modulation is subtracted from the signal that isn't modulated."   

Words to live by my friends.  Words to live by.     

The confusion on this topic often arises in discussions of the old scheme of using a 5 MHz, 9 MHz filter/VFO combination to generate LSB on 75 meters and USB on 20 meters.  This is very convenient, but you need to remember Joel's rule to get this scheme right!  If you start out with a sideband generator putting out UPPER sideband at 5 MHz. and mix it with a VFO running at 8.5 -- 9.5 MHz,  for 20 meters you will take the SUM of the two frequencies.  So no sideband inversion.  You will be happily on 20 meter USB (the mode used on that band).   For 75 meters you will be SUBTRACTING the SIGNAL WITH THE MODULATION (5 MHz) from the SIGNAL WITHOUT THE MODULATION (8.5-9.5 MHz).  So, following Joel's rule you WILL get sideband inversion.  Here you will be on 75 meter LOWER sideband (the mode used on that band). 

It is easy to get confused on this.  I got confused when Steve Smith sent me a 9 MHz filter out of an old Yaesu.  I had visions of using the old 9 MHz 5 MHz scheme.  But no.... With a 9 MHz sideband generator, you can get on both 75 and 20 with a VFO running at 5 to 5.5 MHz, but you won't get the nice sideband inversion situation described above because with neither band will you be subtracting the signal with modulation (9 MHz) FROM the signal without modulation (5-5.5 MHz).

It was very nice that Joel admitted to falling victim to this kind of confusion himself in a column he wrote years ago. 

Thanks Joel!  


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Drake Dongle Derring-Do -- 2B goes SDR (video)

Here I take my Drake 2B  -- arguably the quintessential Hardware Defined Radio -- and connect its first Intermediate Frequency circuitry to an RTL-SDR Dongle, allowing me to digitally process, filter, and display (panoramically!) the signals being inhaled by the ancient receiver.  Another cool tech twist:   To get at the 455 kHz IF signal I use the "Q-Multiplier" jack on the back of the receiver.  This connector was put there to allow for the use of a selectivity enhancing regenerative stage.  So I'm using that connector for a similar purpose, but using technology that wasn't even being dreamed about when that Drake 2-B was being designed in 1961.  


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VK2YAC's Yard-long, In-The-Yard, Bidirectional, Backyard Si5351 Rig

Alf, VK2YAC, wrote to Pete thanking him for the inspiration provided by the LBS project that Pete and Ben launched via QRP Quarterly.   Alf has obviously taken to heart Pete's recommendation re using a BIG breadboard.  

On his web page Alf writes: "Build your homebrew station and join the revolution, it's lots of fun!"   We're with you Alf! 
Alf has more great pictures of his BBR-40 rig and short descriptions of the sub-circuits he has used.  Note Si5351 with Arduino Pro-Mini for BFO and VFO.

http://qsl.net/vk2yac/Page2.html 


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

Born to Solder: Harv's Knack Story

From Harv, WA3EIB:

I'm an avid follower of Soldersmoke and builder of sorts.  I began as a ham operator in 1965.
My parents claim I was born with my hands wrapped around a soldering iron.
 
As you may have noticed, the Michigan Mighty Mite has become a popular rage thanks to Bill and Pete and the Soldersmoke gang. They have encouraged a great number of individuals to study, build and learn. The basics of a simple one transistor transmitter can be a key element to creating, inventing and pushing the brain to greater understanding.
 
When I was first licensed I was encouraged by a fellow ham. This wise man, was way more senior than myself and out of kindness, he sat me down in front of his workbench and grilled me on the key components and reasons for adding a Low Pass Filter in radio transmission. Following the lecture, he pulled the parts for the filter from his cabinet and said, "Now build it!"
 
Fifty years later, that same nurturing education is still with me and our hobby. When I was in New England in the 1970's & 80s, I became friends with Ted Gent, G3ODG. He was a good friend and a real inspiration to art of build. We have long since lost contact with each other however, Ted helped me along as I ventured into solid-state homebrew receivers. 
 
I have enclosed a  photo of a similar one valve oscillator that I built when I was 15. So much thrill is derived when your hands construct a useful element of your radio shack.
 
 
73's
Keep building, keep enjoying!
 
Harv -=WA3EIB=-
Idaho Falls, Idaho  USA

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Greg W's Australia-Finland Mighty Mite (VIDEO)

Greg is a VK6 Australian ham living permanently in Finland.   He has been a SolderSmoke listener for many years.  Greg sent a nice picture and a video of his VK-OH Mighty Mite.   FB Greg!


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SDR Dongle Modified for HF. Watch it work on 40 meters (VIDEO)

With SPRAT 162 by my side, armed with an FT37-43 trifilar wound transformer, I popped open the RTL-SDR dongle.  I had hopes of being able to solder two tiny wires to the unused input pins (3 and 4) but I quickly realized that I was NOT going to be able to do that -- they are far too small for me to work on.  So I did what Ken Marshall G4IIB did:  I took out the SMT caps going to pins 1 and 2 and soldered two small wires there.  This will limit this dongle to HF only -- if I want VHF/UHF I'll just spend another $13 dollars!  You can see the results in the video above.

 

I used the yellow stuff to hold the wires in place.  It was later removed.

Tony Fishpool did a neater job.  See his work here:
https://dl.dropboxusercontent.com/u/1987387/Even_more_on_using_the_RTL2832U_Dongle.pdf


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