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Wednesday, June 30, 2021

10 Pole Crystal Filter Passband as Seen in Antuino and NanoVNA

I continue to work on the "Mythbuster" rig,  but I am taking it slow, trying to learn something from each stage.  I'm especially trying to master the used of the great test gear that has arrived in my shack in recent years:  The Antuino, the NanoVNA, and the TinySA.  

Above you can see the passband of the 10 pole crystal filter as measured across the 50 ohm terminations on the filter.  I use simple FT37-43 transformers to match the filter impedance down to 50 ohms.  I used the Antuino first -- it scanned the passband and held the image on its screen.  I then disconnected the Antuino and connected the NanoVNA.  So in this shot you can see the passband on both devices.  

You will notice that the Antuino says there is a 20db insertion loss.  That's only because in the Antuino 20db is really 0 db loss.  I think the NanoVNA gives a more accurate insertion loss reading -- about 3-5 db.  The cool thing is how similar the shapes of the passband are.  

Tuesday, June 29, 2021

Jack NG2E's Pebble Crusher

 Check out NG2E's Pebble Crusher homebrew transmitter.  Doug DeMaw would be enormously pleased.   

Jack will no-doubt have this 250 mW rig on the some peak along the Shenandoah Valley, handing out QSOs to SOTA fans.   

Jack's blog page has a really nice video on this project: 


Saturday, June 26, 2021

SolderSmoke Podcast #231 -- Travel, SST, Mythbusting, Filters, TIAS, NanoVNAs, DC RX in SPRAT, Drake A Line, Spillsbury, STICKERS! Mailbag

SolderSmoke # 231 is available: 

Annual Field Day Special Edition

Travelogue:   To the Dominican Republic! 
New dog -- Meet Guapo (see below). 

A great Father's Day for Pete and Bill.  I got a TinySA. 
Pete got some cool chick magnet glasses (see below).  
Watch out Newbury Park! 

Bill's Activity

SST Transceiver. Took it to Dominican Republic.
Made only one contact, but QRP-QRP. 
Not a lot of CW activity, and not a lot around 14.060. 
A lot more FT8 visible on the NA5B WebSDR.
That might be better for this kind of operation.  
I might try SST CW out today from the backyard. Field Day!

Fired up my 20 meter DSB NE602 rigs.  Made two contacts.  
Still trying to fully understand the NE602 Gilbert Cell.  Lots of mystery in there. 

Building "The MythBuster."  75/20 with sideband inversion.  

10 pole 5.2 MHz filter.  Used Dishal and AADE. 
Used NanoVNA to see the passband. 
G3UUR for crystal parameters.
Cohn Constant K topology. 

Also used NanoVNA to check input and output impedance on the TIA amps I will use around the filter. 

Pete's activity: 

Article on DC receiver in SPRAT. FB response. 50 receivers under construction.   

Work on Drake A Line.  

Jim Spillsbury. 


The N5JHH IBEW SolderSmoke stickers (see above and below).  How we will use them. 

Tom (Junkbox receiver)
N0ZIB (Curse you, SolderSmoke!) 

Thursday, June 24, 2021

Radio Netherlands -- Bonaire Relay Station

Thanks to Rogier KJ6ETL, PA1ZZ for sharing this video with us (that's Rogier on the Vespa). 

I wonder what they did with the towers and the transmitters?  


Friday, June 18, 2021

Jean Shepherd on CW, and Strange Propagation -- QRP!

From 1965.  Great CW stories from Shep.  QRP!  Shep running 2 watts on 20 CW, working DX. 

He discusses shortwave listening,  and predicted that CW shortwave listening would become more popular (sorry about that Shep). 

It was real hoot to hear the 1965 public service ad from NYC Mayor John Lindsey. 

The Kazoo CW was a bit hard to copy OM. 

Thursday, June 17, 2021

The Stubborn Myth about USB and LSB

It  has been repeated so often and for so long that many of us have come to believe it.  I myself believed it for a while.   Like many myths, it has a ring of truth to it.  And it is a simple, convenient explanation for a complex question: 

Why do ham single sideband operators use LSB below 10 MHz, but USB above 10 MHz? 

Here is the standard (but WRONG) answer: 

In the early days of SSB, hams discovered that with a 9 MHz SSB generator and a VFO running around 5.2 MHz, they could easily reach both 75 meters and 20 meters (True). And because of sideband inversion, a 9 MHz LSB signal would emerge from the mixer as an LSB signal (True), while the 20 meter signal would emerge -- because of sideband inversion -- as a USB signal (FALSE!)  That sideband inversion for the 20 meter signal explains, they claim,  the LSB/USB convention we use to this day. 

Why this explanation is wrong: 

There is a very simple rule to determine if sideband inversion is taking place:  If you are subtracting the signal with the modulation FROM the signal without the modulation (the LO or VFO) you will have sideband inversion.  If not, you will NOT have sideband inversion.

So, you just have to ask yourself:   For either 20 or 75 are we SUBTRACTNG the Modulated signal (9 MHz) from the unmodulated signal (5.2 MHz)? 

For 75 meters we have:   9 MHz - 5.2 MHz =  3.8 MHz    NO.  We are not subtracting the modulated signal from the unmodulated signal.  There will NOT be sideband inversion. 

For 20 meters we have 9 MHz + 5.2 MHz = 14.2 MHz.     NO.  No subtraction here.  No sideband inversion.   

So it is just arithmetically impossible for there to be the kind of happy, easy, and convenient  USB/LSB situation described so persistently by the myth. 


We discussed this several times on the podcast and in the blog: 



This myth shows up all over the place: 

We see the myth here: 


Here the web site owner warns that this is "highly controversial."  Really?  Arithmetic? 


The myth is very old.   Here is a clip from a 1966 issue of "73" magazine: 


Finally, to my disappointment, I found the myth being circulated by the ARRL, in the 2002 ARRL Handbook page 12.3: 

The fact that the Handbook attributed this to a desire to "reduce circuit complexity" by not including a sideband switch should have set off alarms.  We are talking about hams who built their own SSB rigs, usually phasing rigs.  A sideband switch would not have added significant circuit complexity. I think they could have handled it. 

It is interesting that earlier ARRL Handbooks do not repeat this myth.  I found no sign of it in Handbooks from 1947, 1959, 1963, 1973, and 1980.  And I found no sign of it in several editions of that great ARRL book "Single Sideband for the Radio Amateur." 

For my next homebrew rig, I will build a rig that DOES do what the myth promises.  I will have the SSB generator running on 5.2 MHz USB.  The VFO (out of an old FT-101) will be running around 9 MHz.  So for 75 meters we WILL be subtracting the signal with the modulation from the signal without the modulation:   9 MHz - 5.2 MHz = 3.8 MHz.   There will be inversion.  This 75 meter signal will be LSB.   For 20 we will just add the 5.2 MHz USB signal to the 9 MHz  VFO.  There will be no inversion.  We will have a USB signal on 20.   I'm thinking of calling this new rig "The Legend." Or perhaps, "The Mythbuster." 

Tuesday, June 15, 2021

Hi Def 360 Degree Panorama from the Mars Perseverance Rover

Put this on full screen view and set for max Hi Def presentation. 

You can stop the video around the 1:10 mark, but then still use your mouse to pan around for a full look at the area (without the annoying labels that appear at the beginning).  

Monday, June 14, 2021

M0NTV's Latest FB SSB Transceiver

Wow, Nick has a really wonderful rig and has made this great video to explain it. 

Elements that I really liked: 

-- The simple mic and compression.   Very nice. 
-- Termination Insensitive Amps.  TIAs Rule! 
-- Grey Altoid-like boxes. 
-- Diplexers!  Yes! 
-- Doug DeMaw S-meter. 
-- No AGC.  
-- Pentium CPU cooling fan. 
-- References to EI9GQ (I must get his book!) 
-- Al Fresco!   Good luck with boxing it up Nick. 

Santo Domingo Shack on 12th Floor Balcony -- SST QRP CW

June 2021.  We were in Santo Domingo, Dominican Republic.  At this point we were in a 12th floor apartment in the center of the city.  I would take my SST 20 meter CW transceiver and EFHW antenna out on the balcony.  I made no contacts from this location, but one of  my CQs was picked up by K9TM on the Reverse Beacon Network (see below).  All the other RBN spots were the result of calls from the eastern tip of the island. (Click on the RBN image for a clearer view.)


Saturday, June 12, 2021

Good News! The Termination Event May Be Coming Soon! Solar Cycle 25 Could Rival Cycle 19!

Wow.  Cycle 25 might be as good or better than Cycle 19.  Pete cut his radio teeth on Cycle 19.  I was born during that cycle.  Let's hope these scientists are right!  See chart below. 

Thanks to Thomas over at SWLing Post for alerting us to this important news.   

Thursday, June 10, 2021

Tom's Receiver -- A 20 Meter Superhet Built From the Junkbox

Wow, this is really an amazing project.  It is so good that I'd like to believe that it is really "all our fault," but the credit obviously goes to Tom, the very intrepid builder.  In a more just world, Tom would be given a ham radio license solely on the basis of this project.  Great work Tom.  We look forward to more Solder Defined Radios from your workbench.   

Dear Bill and Pete,

I stumbled across your podcast a few years ago. I had no interest in
amateur radio, I was just looking for an electronics podcast that
actually discussed electronics (naming no names here, obviously).
Well, the inevitable happened, and some of your enthusiasm rubbed off
on me. I now find myself humbly enclosing a photograph of my first
homebrew receiver for 20m.

The project was one of those "spontaneous construction" affairs,
triggered mainly by breaking up an old satellite receiver (I've
honestly no idea what it was for) which yielded up several SBL1s and a
10.7MHz crystal filter - these form the key elements of the new
receiver. It's a full SDR (solder defined radio) of a conventional
single-conversion superhet arrangement. The chief abnormality is that,
because the IF filter is as wide as the proverbial barn door, I only
use "one edge" - the other half of the passband being provided after
conversion to baseband. Of course, that only works if there are no
massively strong stations in the 6kHz above where you're listening,
but it seems to be ok most of the time. It does give me the advantage
of being able to adjust the lowpass point of the AF signal by
adjusting the BFO, which is nice.

You'll notice there's a lot of "digital nonsense" in the picture, for
what's supposed to be an analogue radio. This "supervises" the two
VCOs: There is an FPGA which implements a pair of frequency meters and
an STM8 microcontroller which is in charge of adjusting the control
voltages to keep the VCOs where they should be. It's all slightly
roundabout because I wasn't clever enough to design a PLL which would
give the required resolution (and I wanted to do something "more RF"
than throw down a DDS chip). 
This gives me stability as well as fancy bells and whistles, like
numeric readout, tuning info via RS232, automatic scanning and
frequency presets. I've used a (cheap) industrial/automation style
encoder for the tuning control, which gives a lovely analogue-like

Despite my best efforts (and a lot of ferrite in strategic places) I
wasn't able to keep all the digital spurs out of the receiver. So I
devised a dirty hack by way of a button which will shift the MCU an
DAC clocks to a different frequency. I can't remove the spurs, but now
I can hide them!

So far I've played with a "long" wire and a little shielded loop for
antennas - I'm in a first floor flat with a lot of noise locally, and
my plan is to get a loop up in the loft space (so the next project
might be a rotator!). I fancy maybe seeing if I've space for an
inverted V, too.

You'll notice that I've not attempted a transmitter. That, of course,
is because I'm not yet a licenced ham! However, I'm intending to put
that right sometime later in the year. Then - who knows - I might make
a contact!

Thanks for reading (although really it's the least you could do given
that this *is* all your fault) and I hope you've enjoyed hearing about
all the trouble your little podcast has got me into.

Keep up the good work gentlemen,
73 from South-West England.

PS. I also have a copy of Bill's book, which I've very much enjoyed.

Wednesday, June 9, 2021

Pete's Drakes

Pete Juliano N6QW has on his blog two very nice videos about the Drake A-line.  

As long-standing fanatical fan of the Drake 2-B, I was struck by the similarities between the 2-B and the R4 seen in Pete's video:  

-- The S-meter is the same. 
-- The passband tuning control and indeed the visible internal circuitry for the passband tuning seem to be the same.  
-- Drake even used the same "hook" for selectivity selection.   

The transceive feature with the T4 seems very nice.  

Pete's first video is above.   Pete's second video, showing his first contacts with the newly acquired A-line, can be seen here: 

Thanks Pete! 

Monday, June 7, 2021

Dino's Test Gear -- KL0S at FDIM 2021

Great test gear advice from Dino KL0S.  Thanks to Dino and to QRPARCI!  


Sunday, June 6, 2021

VK3HN on Scratch Building (Video)

Lots of wisdom and good info in Paul Taylor's presentation.

Paul's comment on the impact of abundant LiPo power in the field -- we no longer have to scrimp and optimize power consumption -- was very interesting.   

And thanks for the nice mentions of the SolderSmoke podcast. 

Thanks Paul!


Friday, June 4, 2021

To Mars in 1964 -- Building the Camera and Radio Systems

This is a really excellent video showing how JPL engineers and technicians designed, built and tested the first video camera system sent to Mars. 

-- It was essentially a Slow Scan TV system built around a Vidicon tube. 
-- Data was sent back in digital form. 
-- The first Digital-Analog conversion was done using COLORED CHALK!
-- The method used to protect the Vidicon tube from vibration was derived from the packing material used to mail the tube to JPL from Texas. 
-- During testing, JPL had all the circuitry spread out in what we would call "Al Fresco" style. 

Thanks to Dan Maloney at Hack-A-Day for alerting us to this.  Dan has an excellent article about the mission here: 

Thursday, June 3, 2021

Remastered! The Secret Life of Radio -- With Updated Comments from Tim Hunkin

Thanks to Stephen 2E0FXZ for alerting us to this important video. 
We first posted about the original many years ago.  We were delighted to learn that they have remastered the video and added 10 minutes of retrospective commentary from Tim Hunkin.  

Here are some of my reactions after watching the updated version:
-- The Marconi videos were amazing.   I actually met Elettra at a diplomatic reception in Rome.  
-- I was pleased to learn that Marconi was trying to "call up" Mars.  FB OM. 
-- My son Billy and I sat in that same Royal Institution auditorium where, 100 years before, Oliver Lodge had demonstrated spark gap technology. 
-- Tim's comment on the connection to supernatural beliefs was right on the mark.  We found out that the house we lived in in London was a center for occult beliefs and practices. 
-- Those square lantern batteries brought back fond childhood memories. My first power supplies.
-- The Rexophone -- used by Rex. 
-- Very cool of Tim to homebrew a coherer.  Extra credit for that.
-- One of the capacitors looks familiar.  EF Johnson? 
-- I agree with Tim -- crystal radios are a must-build for true radio hams.  And do it with galena and a cats whisker. 
-- Finally, the RCA ad introduces a term we might want to surreptitiously enter into the Enhanced SSB lexicon:  That "Golden Throat" sound.   

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column