Using SDR without SDR Hardware -- N2CQR Adjusts Analog BITX20 using Web SDR

I know what you are thinking:  Software Defined radio with the TOTAL elimination of hardware? WHERE IS BILL AND WHAT HAVE THEY DONE WITH HIM?  

Relax my friends.  All is well at SolderSmoke's East Coast HQ.  In fact, just yesterday I was making use of one of the systems described in this video.  Here's how: 

I was on 20 meters with my BITX 20 Hardware Defined (HDR) homebrew transceiver. Everything was going smoothly.  We have some sunspots now, so DX is once again possible.  I heard a loud U.S. station (that will remain anonymous) calling CQ, so I gave him a call.  

The trouble started right after he looked at my QRZ page. You see,  I have pictures of my homebrew rigs there.  These images sometimes trigger hostile reactions, especially from guys who have almost their entire stations INSIDE their computer boxes.  I also admit to occasionally making things worse by pointing out that it is possible to build a BITX20 for about five dollars U.S.   Some guys apparently don't like hearing about this. 

Anyway, the fellow I was talking to proceeded to give me a very blunt and harsh signal report:  "Well, I suppose your signal is strong enough, but your audio is TERRIBLE!"  Interpersonal relations pointer:  This is NOT a good way to alert a fellow ham to possible technical problems in the rig that he has built by hand, from scratch, in his home workshop.  Especially when the person delivering the harsh signal report is using a "rig" that was built by credit card in a robotic factory on the other side of the planet. 

So that QSO ended rather quickly. But I did want to follow-up in the comment about the audio.  And here is where I turned to Web SDR.   Mehmet NA5B has a really nice WEB SDR receive system in Washington DC, just about 8 miles east of me.  Before 20 meters opened, I called up Mehmet's SDR on my computer, tuned it to the frequency of my transceiver and watched the screen as I asked if the frequency was in use.  I then issued a couple of hopeless CQs, again watching the screen.    I could see in NA5B's waterfall that my signal was indeed seriously lacking in low frequency audio. 

Now it was time to turn to hardware.  Rig on the bench, 'scope and sig generators fired up,   I quickly determined that the problem most likely resulted from my placement of the  carrier oscillator frequency in relation to the homebrew USB crystal filter.  I had placed it about 300 Hz too low.  This resulted in a low AF frequency roll off not at the desired 300 HZ, but instead at around 600 Hz.  That would make the audio sound "tinny." So I moved the carrier oscillator up 300 Hz and went back to Mehmet's SDR receiver.  I could see that the lows were now at the right level.  Thanks Mehmet. 

One note about the audio coming out of the many SDR radios on the air:  When you look at the passbands in the Web SDR receivers you can see audio going almost all the way down to the frequency of the suppressed carrier.  With non-SDR rigs  you usually see a gap of around  300 Hz between the carrier freq and the start of the SSB signal.  This is often the result of our filter rigs having IF filter skirts -- you would place the carrier oscillator frequency a bit down the skirt -- this would help with opposite sideband suppression and all you would be losing would be the lows below 300 cycles, which weren't really necessary anyway.  I had placed the carrier oscillator too far down on the skirt.  

Of course, sometimes SDR rigs will also have a gap between the carrier freq an the start of the audio if the operator has set the passband this way, or if the microphone attenuates below 300 Hz.  But you see a lot of signals with audio filling almost the entire passband --some of the "Enhanced SSB" guys are running audio passbands that go as low as 50 Hz.  

Has anyone else noticed this "full passband" effect when looking at the waterfalls?  
Any other tips for using Web SDR for troubleshooting?  

Presence (Absence?) and Direct Conversion Receivers (with wise comments from Farhan)

Hello Bill,

    I was reading an online article by Wes Hayward, W7ZO  from 1968  about the history of direct conversion receivers (http://w7zoi.net/dcrx68a.pdf)  .  It was linked in an email in qrptech.    It recounts how he had first build a dc receiver with a single diode for the detector, and how microphonic it was, and dissatisfying an experience.   This was in the early days of solid state devices, and so they were hard to come by.   He describes meeting another ham engineer at work Dick Bingham, W7WKR who immediately recognized that what he needed was a diode ring mixer.    The story goes on to describe their experiments, and success at this design.   

  They decided to write up the design for QST.   I won't bore you with the details...the article is well worth reading about how Wes mailed the radio and the design to ARRL, and how it ended up in the hands of a new person on their staff there, Doug DeMaw, W1CER (later W1FB.).  Here is an excerpt from the article describing Doug's reaction to the receiver:

"This was the epiphany, the moment when Doug realized that solid-state technology had produce a new way to build a simple receiver. Doug tuned the receiver higher in the band and found some SSB. Again it was like nothing he had ever heard. It was as if the voice came from the same room. Doug used the term presence in his description."

Here I present the earliest use, that I know of, of presence being used to describe a receiver.    I have to say when I read it, I immediately thought of you guys, and decided to share.

Thanks for all you guys do.

   dave    /nt1u

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

Bill replied:

Thanks Dave.   Yea, that's the 1968 article that launched the use of DC receivers.  I had forgotten about DeMaw's early use of "presence." 

Just to cause trouble, perhaps we should start commenting on "absence"  i.e.  "I dunno OM, I think your rig lacks a bit of absence in the mid-range... turn menu item 63b to ELEVEN!"  

:-)

73 Bill 

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

 

Farhan wrote: 

Mon, Aug 3 at 3:22 PM

When I got my license, my friend Anil SM0MFC was living in Hyderabad. He lent me his HW-8.  I stringed up a 40 meter dipole with a lamp cord and worked with it. Somehow, the combination of the lamp cord length and the 40 meter inverted V made it resonate on 20 m as well. The HW-8 had a nominal antenna tuner and I worked pretty good DX.

Till date, it remains the best receiver that I have used for regular contacts. The only trouble it had was the the MC1496 was a nominal detector, it overloaded heavily with shortwave broadcast stations. There was an unnecessary RF amplifier in the front-end that they could have done without.

I made several direct conversion receivers, but never managed to hang on to any. This makes me want to build one, one of these evenings. I even have a KK7B R1 kit. but real men solder on without any PCBs or even circuit diagram!

A 7/14/21 direct conversion radio that puts out 3 watts of power is what my ideal setup would be. I am not too bothered with the images on CW. I just tune them out in my head. Real soon now, at the moment, i am trying to finish a radio that has been in the works for years.  Finally, I am making some headway.

-f

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

Farhan of course is no slouch in the DC receiver area.  Years ago he wrote a wonderful post about building a DC receiver with his cousin for her class project: 

 https://web.archive.org/web/20171109081542/http://www.phonestack.com/farhan/dc40.html

Included in this post was a passage that I included in my book  SolderSmoke -- Global Adventures in Wireless Electonics: 

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

Why build a receiver?

    Why do you want to build it? These are available at the Dubai Duty Free asked Harish, an old friend, when he spotted us struggling over the DC40 one evening. I didn't have an answer to this question and considering the amount of work piled this quarter, it appeared to be a sensible thing to ask.

    I think this question is answered by us all in different ways. My personal answer would be because we human beings are fundamentally tool builders. We have an opposable thumb that allows us to grip the soldering iron.

    For an engineer (by the word ‘engineer', I don't just mean those who have a degree, but anyone who applies technical knowledge to build things) the act of building a receiver is a fundamental proof of her competence and capability. It is much easier to put out 1 watt signal than it is to receive a 1 watt signal.

    A simple definition of a good receiver is that a good receiver consistently, clearly receives only the intended signal, such a definition hides a wide range of requirements. The receiver has to be sensitive enough to pick up the weakest signal imaginable (note: clearly), it has to be selective enough to eliminate other signals (only), it has to be stable enough (consistently).

    For a ham or an engineer, building a usable receiver is a personal landmark. It establishes a personal competency to be able to understand the very fundamental operation of the radio and mastery over it.

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

Bill:  OM Ryan Flowers did a 5 part series on building the DC40.  If you are want to build one, I suggest you use the schematics on Ryan's site.  There was an error in Farhan's original schematic -- Farhan corrected it but some of the incorrect schematics are still floating around the internet.  Here is part one of Ryan's series: 

 https://miscdotgeek.com/building-direct-conversion-receiver-part-1/ 

Farhan's DC40

First Amateur Transatlantic SSB Contact W2TGO--DL4PA September 9, 1949

Mars: Book Review, Martian Propagation, Martian Moons as VHF Repeater Sites

In SolderSmoke #224 I mentioned the Mars Trilogy by Kim Stanley Robinson.   I found a book review in The New Yorker (see below).   In Red Mars they mention that there is no ionospheric propagation on Mars.  W1PJE and K1RID point out that this is incorrect -- there is ionospheric propagation on Mars.  K1RID provides a link to a really detailed NASA study of this question (it includes discussion of the effect on propagation of Martian dust storms -- good to know!). Finally, 2E0CHK suggests placing VHF repeaters on the two moons of Mars.  I found a good article about the overhead passes of these moons.   See below for all.  

AND REMEMBER: THE ELSER-MATHES CUP REMAINS UNCLAIMED! 


Here's a review from The New Yorker: 

https://www.newyorker.com/books/page-turner/our-greatest-political-novelist

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

Hello Pete and Bill,

Listened to your latest SolderSmoke podcast. Enjoyable as always. But you should correct the record: Mars does have an ionosphere!

https://www.google.com/amp/s/www.wired.com/2017/04/mars-ionosphere-cold-lifeless-filled-heavy-metals/amp

The peak daytime electron density ("M2 layer") is low in altitude - perhaps 130+ km, about our E region - and density is like our E region too (5-10x lower than our F region). So for the Mark Watneys carrying their Homebrew rig and inverted V, probably only a few hundred km to the first skip zone. More NVIS flavor than anything else.

Fun to think about. You should go and test it out!

73

Phil W1PJE

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

BTW, this made the rounds in our club last year:

https://descanso.jpl.nasa.gov/propagation/mars/MarsPub020318.pdf

dit dit

73 de Ed, K1RID
Newburyport Electronics & Radio Society
www.K1YRD.org

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

2E0CHKAugust 1, 2020 at 4:04 PM

Hey Bill,
No skip on Mars ?
No ionosphere ?
Every cloud has a silver lining, even if Mars doesn't have any clouds ;)
Mars has two moons.
Could be paradise for Moon Bounce aficionados. No ionosphere or F layer to get in the way. VHF can get around corners after all.

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

Here is an article describing the overhead passes of the two Martian moons: 

https://www.space.com/28403-astronauts-mars-skywatching-phobos-deimos.html#:~:text=So%20an%20observer%20on%20the,and%20set%20in%20the%20west.

How to Sweep, Plot, and Measure Filter Output in LTSpice

The other day Pete N6QW posted a very nice graph of a bandpass filter's passband.  He was using LTSpice.  I realized I had a serious gap in my LTSpice knowledge -- I wasn't sure how to do this.

The charming video from India explains how.  Really useful.

OSCAR 100 Geosynchronous Satellite Video

I guess the title for this post could also be "How the Other Half Lives."  I'm sure at least a few of you will be thinking about building an OSCAR 100 station after watching this video.  But if you are in North or South America (with the exception of the Eastern tip of Brazil), forget about it.  OSCAR 100 is geostationary over the other side of the planet.  And amateurs have no equivalent on this side of the world.  But we can listen in using the Web SDRs. 

A couple of interesting bits from this recording.  You can hear G7BTP's coming back from the satellite with a bit of a delay -- he is obviously monitoring the downlink when he is transmitting.  DL8FBH says that he doesn't have a receive system of his own -- he is using a WEB SDR station (as I was) for the receiver. 

  

Homebrew Resistor Kit -- Drew's Mouser BOM

I put the resistors in parts envelopes and cardboard boxes

Hi Bill,

You mentioned wanting to get a resistor kit.  If you'd like, I can

help you do what I did.

First, I looked at:  https://en.wikipedia.org/wiki/E-series_of_preferred_numbers

Then I noodled about it a bit.  And looked at mouser.

A tiny bit of code put together a copy and paste list of part numbers

that I pasted onto mouser's BOM order form.  And bob's your uncle.

In my case, a particular manufacturer's 1/4 W metal film 100 ppm as

they were 1.9c @ 100 pieces.  I created a copy and paste BOM for E6

over 4 decades plus E3 for a 5th and 1M and 49.9 ohms. Less than $2

per value for 29 values.  Not a bad price for the size of the resistor

kit.  I also figured if the value gap was too large, I could fill it

in with the other half of the E12 series.  (E6 series is every other

E12 series value.)

This could be tweaked.  Perhaps fewer resistors in each value.  Or add

some more special values or whatever.

Mouser was kind enough to cut tape and put each value in a flat

plastic baggy with a label as to what was inside.  Sorted in a file

box, it's a snap to grab a resistor.

Perhaps this is something I should post online to share?  Maybe

someone else already has?

On my todo list is to construct my self a homebrew BOM of capacitors.

If you're interested, I could update this and let you know what Mouser

can do for you.  It may not be your preference, but it is an

interesting option.

Best regards,

Drew

n7da

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

Drew:   Your message caused me to think about what I really need in a resistor kit.  I have been using some other resistor kits, but I end up using ALL of certain values and NONE of others.  Your message made me realize that there is valuable data in those old kit packages.  

I took a look a them this morning.   It seems I use the following values:  4.7, 10, 47, 100, 220, 330, 470, 1k,  2,2k, 3,3k, 4,7k, and 10k.  That's about it.  So maybe I just need to go to mouser and order, 50 of each.  I'm thinking 1/4 or maybe 1/2 watt? 

The packaging you describe sounds great.  How can I get Mouser to do that for me?  

I don't think I need the more sophisticated approach you used, but I'm sure we have listeners who could benefit from it. 

Any further suggestions?  

Thanks again,  

73  Bill 

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

Hi Bill,

Sounds very good.  It turned out to be simple for me to order a
ridiculously well stocked resistor kit, but doing something custom is
actually a great idea.  If you want both 1/4 and 1/2, get both.  (I
figured I could always make a 1/2 W resistor out of 2 1/4 watt
resistors.)

The packaging is just what they do.  No extra charge other than their
regular shipping and handling.

So, I did this in late 2018.  When ordered, two values were
backordered, but they shipped them out a month or 6 weeks later or
something.  Checking now, 660-MF1/4DC1000F (a 1% 100 ohm metal film
1/4 watt), I see it is out of stock with an ETA of June 1st for 10K
they are ordering.  The other P/N that was backordered was
660-MF1/4DC1503F.  Who knew 100 and 150K ohms were extra popular?
150K is in stock right now BTW.  Maybe it's random what they run out
of?

Best thing is you copy and paste your list of P/Ns and quantity for
each and bam Mouser will tell you pricing and if anything is
backordered, etc.  If you don't like what you see, change your list
and try again.

I actually thought about what I wanted, then looked at Mouser to see
what they had and what the pricing was on it.

So, from this particular resistor family, I see the pricing is what it
was a couple of years ago.

if you order 50 pieces of that 150 or 100 ohm resistor, that is:
50*$0.055 = $2.75 for 50 resistors.

If you order 100 pieces of that 150 or 100 ohm resistor, that is:
100*$0.019 = $1.90

IT"S CHEAPER TO ORDER 100!  Well, at least for this resistor family
and for Mouser's price breaks.  You have to look at the price breaks
versus volume.  And of course, understand the minimum you need and the
maximum you can store in your lab.  :-)  Don't be ordering 10,000.
:-)

So, price breaks for these they show:

Qty.    Unit Price
1    $0.23
10    $0.055
100    $0.019
1,000    $0.014
2,000    $0.009
10,000    $0.008
25,000    $0.007

You can see that there's a good break at 10, 100, and 2,000.  The
quantity with a good break really depends, so you would have to look
at different vendor product families to see.  I don't think I looked
very long.  I probably knew I wanted 1/4 W (may have considered 1/8 or
1/2, don't remember).  I also think I knew I wanted metal film.  When
I saw the pricing on these at 100 pc and with 1% tolerance (so I could
double out to E12 series and have it make sense if it turned out to be
useful for me), I stopped shopping.

Here's the full BOM I ordered.  The top part is some extra parts I
wanted and those couple of special resistor values.  The lower part
was generated by just a few lines of python:

-----
G6K-2F-Y-DC12|8
1N4007FFG|100
1N4448|100
2N3904TAR|100
2N3906TAR|100
2643000101|100
2643002402|25
2673002402|25
2661000101|25
1C10X7R104K100B|50
1C10X7R103K100B|50
ECA-1HM101|25
ECA-1HM100|25
TIP29CG|5
TIP30CG|5
1N5355BG|10
PR01000104700JR500|10
PR01000102200JR500|6
MF1/4DC1800F|20
MF1/4DC2400F|20
MF1/4DC36R5F|10
FC2053-440-A|100
MF1/4DC16R5F|20

MF1/4DC10R0F|100
MF1/4DC15R0F|100
MF1/4DC22R0F|100
MF1/4DC33R0F|100
MF1/4DC47R0F|100
MF1/4DC68R0F|100
MF1/4DC1000F|100
MF1/4DC1500F|100
MF1/4DC2200F|100
MF1/4DC3300F|100
MF1/4DC4700F|100
MF1/4DC6800F|100
MF1/4DC1001F|100
MF1/4DC1501F|100
MF1/4DC2201F|100
MF1/4DC3301F|100
MF1/4DC4701F|100
MF1/4DC6801F|100
MF1/4DC1002F|100
MF1/4DC1502F|100
MF1/4DC2202F|100
MF1/4DC3302F|100
MF1/4DC4702F|100
MF1/4DC6802F|100
MF1/4DC1003F|100
MF1/4DC1503F|100
MF1/4DC2203F|100
MF1/4DC3303F|100
MF1/4DC4703F|100
MF1/4DC6803F|100
MF1/4DC49R9F|100
MF1/4DC1004F|100
-----

So, your BOM (4.7, 10, 47, 100, 220, 330, 470, 1k,  2,2k, 3,3k, 4,7k,
and 10k) would be the following.  Added the 4.7 by hand and deleted
the other values by hand.  Qty 100 each.
-----
MF1/4DC4R700F|100
MF1/4DC10R0F|100
MF1/4DC47R0F|100
MF1/4DC1000F|100
MF1/4DC2200F|100
MF1/4DC3300F|100
MF1/4DC4700F|100
MF1/4DC1001F|100
MF1/4DC2201F|100
MF1/4DC3301F|100
MF1/4DC4701F|100
MF1/4DC1002F|100
-----

Mouser.com.  Services & Tools button.  BOM Tool button.  Login (they
want account for the tools.  I can't complain.)  Upload spreadsheet or
copy and paste.  In this case, copy and paste.  In fact, copy right
out of this draft email and into their tool.  Next.  Then they ask me
for a name for the BOM and if I only want RoHS.  (RoHS is up to you.
I picked only RoHS, because I know all these parts are RoHS and it
won't warn me about lead poisoning or anything.)  Process BOM.
Blammo.

I had the 4.7 wrong, but they figure it out.  Ouch.  Pricey.  Maybe
you don't need so many, but $4.6 for 100.  Parallel a couple of 10
ohm, you'll have less parasitic L in your emitter circuit.  Change the
BOM before you click the add all to cart.  No problem.  Or maybe 4.7
is worth the extra money to a high roller such as yourself.  :-)

2 parts are at 0 inventory.  The 100 we knew about.  470 as well with
6K arriving 15June.  Yes, those ETAs are perhaps questionable.  Dunno.
They will ship you what they have and ship the rest later AT NO EXTRA
CHARGE.  :-)

A third part is at 123 pc inventory.  Act now before they are all out!
:-)  220 ohms.  6K due end of June.

The above would be $25.50 plus less than $10 for their cheapest
shipping option.  Not a bad price for a well stocked CUSTOM kit and
it's really easy to do.  And these are good parts with specifications
and tempcos etc. all in the data sheet.  Sure, you don't need it 99%
of the time, but if you wanted it, because you were doing something
fussy, you have it.

You could cut that price down quite a bit if you went carbon or wider
tolerance.  (Who needs 1%?  This is electrical engineering, not
mechanical engineering!)  Or maybe another manufacturer.  It's easy to
browse on Mouser and figure out those other options quickly and what
it may do to help you out.  Of course, when you get to a price of
$0.00, you still have the flat rate cheapest Mouser shipping as the
floor on what price you can achieve.

Mouser will also give you a print and email with price, part number,
description of everything in your custom kit.  And each pouch is
labelled.  Crazy!  :-)

Another crazy thing is with these BOMs is that you can easily share
them with others.

Best regards,

Drew
n7da

SolderSmoke Podcast #224: Mars. Spurs. Bikes. SDR. NanoVNA. Antuino. MAILBAG

SolderSmoke Podcast #224 is available:

http://soldersmoke.com/soldersmoke224.mp3

1 August 2020

--The launch of Perseverance Mars probe with Ingenuity helicopter.

--China’s Tian Wen 1 on its way – radio amateur Daniel Estevez EA4GPZ is listening to it! 

--Sci Fi Books:  Mars Trilogy by Kim Stanley Robinson.  No skip on Mars :-(

--We have some sunspots!  SFI now 72 and the Sunspot number is 23. 

Bill's bench: 

--Conquering Ceramic Spurs in Q-31   Roofing filter -- sort of 

--NE602 for a Q-75 converter – Gilbert Cell. 

--Measuring low power levels out of NE602.  Antuino better than 'scope . 

--NanoVNA   Really cool stuff.  SDR in there. 

--Building a 455 kc LC filter from QF-1 rubble. Using LTSPICE, Elsie... 

--Reviving my bicycle AM radio – The “All Japanese 6”

--Understanding L Network impedance matching. 

--Bill’s new resistor kit from Mouser. Thanks to Drew N7DA. 

SHAMELESS COMMERCE:  PATREON, AMAZON SEARCH.  THANKS

Pete's Bench: 

--Lockdown Special 

--BPF work on SDR Rig

--I U W I H 

Mailbag:

VK3HN Summit Prowler 7

VK2EMU “The Stranger”

SM0P  HB uBITX in Dubai

AE7KI  Worked him in VK from London

ON6UU  EA3GCY’s 4020 rig

KA4KXX A Simpler Mighty Mite

W9KKQ M19 DMR

KD4PBJ Radio Schenectady

W3BBO 12AU7 Regen

KE5HPY Another 12AU7 regen

N5VZH Ne602 Converter

KY3R Wall Art

G4WIF  Spectrum Analyzer in your pocket

W2AEW  Talks to UK Club

KK0S Sent 455 Kc IF cans

KL0S Making 9Mhz filters

VU2ESE  Diving into simple SDR schemes

Dean KK4DAS  Amateur Radio Astronomy

D-Lab Re-Caps a Drake 2-B (Very Economically)

A bit ugly, but it gets you there!   I like it. 

Thanks to John KE5ETX for alerting us to this video. 

A 75 Meter AM Quarantine Converter for the Q-31 Receiver (video)

A while back Fred KC5RT sent me a nice collection of parts, including some 6 MHz crystals.  I had been thinking of making a converter to put ahead of my Q-31 receiver.  When Fred's 6 MHz rocks arrived, I knew that The Radio Gods Had Spoken (TRGHS).  

I found some NE602 chips in the junk box.   I used an Altoid-sized box for the case.  The toroids are from W8DIZ.  I use trimmer caps from KC5RT to resonate the input and output circuits.  

Hooray!  Now I can listen to 75 Meter AM on the Q-31.  I may have to build a transmitter to go with this contraption.  

Thanks again Fred. 

Paul Taylor's Quarantine "Summit Prowler 7" and some Radio Archaeology

Paul Taylor VK3HN has really outdone himself in this video (above) and blog post. He describes coming across a somewhat mysterious homebrew SSB exciter with some cryptic markings on it. Paul eventually figures them out.  We still don't know who the builder VK3WAC was -- can anyone find him in their logbooks? 

As Paul goes through the description of the transceiver he built around the mystery exciter, he mentions a number of hombew heroes including Farhan VU2ESE, Peter DK7IH, Eamon EI9GQ (I have to get his book!), and Don W6JL.  Also,  our beloved SSDRA book plays a prominent role in the story. 

Paul's video is really beautiful -- at one point the camera pans the landscape and we see kangaroos in the field.  It is also refreshing  -- as we suffer in the heat of the northern hemisphere summer -- to see Paul and his friends out on the summits in their winter coats and hats.  

It looks to me as if Paul built this rig during the current emergency, so I will list it as a Quarantine rig.  Every dark cloud has a silver lining, and Paul's rig has added a bit of silver to the dark COVID cloud.  Thanks Paul. 

https://vk3hn.wordpress.com/2020/07/26/something-old-something-new-a-four-band-5w-50w-ssb-cw-transceiver-summit-prowler-7/

Alan Wolke W2AEW on IMD, NanoVNA and more (presentation to UK club)

This video is another reminder of how lucky we are to have Alan Wolke W2AEW as a fellow radio amateur, and as a teacher and mentor. 

In this video, Alan is talking to the Denby Dale Amateur Radio Society in Yorkshire, UK. 

The first part of his talk is about IMD products, the importance of 3rd order products, and the benefits of attenuation. 

The second part of the talk (after a few questions) is a look at the NanoVNA, which Alan cites as the "Toy or Tool of the Year."   

I learned a lot from both portions of the presentation.  I now find myself wanting an H4 model of the NanoVNA (bigger screen).  Or maybe even an F model.   Thanks to Alan, I now know what S21 and S11 means. 

Thank you Alan, and thanks to the Denby Dale ARS.  

73  Bill 
  

ANOTHER 12AU7 REGEN! W3BBO's Quarantine Receiver

Hi Bill,

I was really impressed with Chuck KE5HPY’s 12AU7 Quarantine Regen!  A very nice build and my hat is off to him!  It caught my eye, as I also built a 12AU7 regen during this period, my first “Hollow-State” unit in sometime. 

It would be interesting to find out what other construction projects fellow hams have involved themselves with during this trying time.

Keep melting solder!

73 de Bob W3BBO

  

Radio Schenectady

A while back I posted a picture (see below) of the shortwave dial of an old receiver used by my wife's grandfather.  I noted the odd  presence of 'Schenectady"  among the exotic foreign locations on the dial.  Pete immediately connected the dots by noting that Schenectady was the home of General Electric.  This week Chris Waldrup KD4PBJ sent us a great web site describing the shortwave stations in Schenectady.  Check out the tube that runs 100 kw AM (Big Bertha).  

https://www.radioworld.com/news-and-business/schenectady-shortwave-transmitters-1941

Chris also sent information about BIG AM broadcast band stations: 

In addition to Schenectady being home to  GE it is the city of license to clear channel AM 50 kW WGY 810.  WGY was started by GE so if the radio was GE it was probably a way to promote their station at the time. I heard mention of Rochester too and that would be for 1180 WHAM another 50 kW clear.  Both WGY and WHAM are still there going strong banging out their 50 kW.

And Pete reminded us of KDKA, describing its long-lasting impact on one of his ears:  

Let us not forget KDKA in Pittsburgh at 1020 which I think is no longer clear channel. I used to listen to KDKA on my crystal set when I went to bed at night. My bed had an exposed bed-spring which was my antenna. To this day there is a slight kink in one of my ears where my Brush headphones rested –I am a side sleeper.

KE5HPY's 12AU7 Quarantine Regen -- FB!

Bill and Pete:

Thanks for upping the frequency of your podcasts.  Each one is a welcome note to break-up the COVID monotony.

Following on to Bill’s 31m rx, I am pleased to have a new regen on the air and performing well.  This started as the 12AU7 Hartley circuit found on the web; however, the original circuit needed some further work IMO.  I made a number of modifications – outboard 30 MHz LPF (to remove our local Spanish FM station), inductive antenna link, variable cap for antenna coupling adjustment, up to 24V on the plate, extra by-passing, NE5532 audio section vs LM386 and a switched cap for a lower “band”.  It’s still a starved triode oscillator/audio amp and it has that regen presence.  Best DX is Singapore (BBC) and Madagascar although it’s ideal for easy listening on 19-60m to Romania, Greece, Cuban music, Spain, etc.  As Bill said, there is still plenty worth listening to on a homebrew AM rx.  40, 30 and 20m copy OK, but bandspread is tricky! Adjusting regen is good for +/- 1 kHz, kind of a poor man’s BFO adjustment.   I heard a TI station calling CQ on 20m and called him back on my Icom for a QSO. 

By the way, this rx has some serious vintage mojo – Hammarlund varicap, National coil form, Millen dial and an RCA tube.  The all-star team plays great together! It’s a kick seeing the filament glow while putting RF through recycled parts made decades ago.

73,

Chuck

KE5HPY

A Quarantine Mighty Mite

'Tis a thing of beauty. 

Bill/Pete:

    I just decided here over the COVID period to head back to basics here and build a Michigan Mighty Mite with a Color burst crystal I had here. And wouldn't you know it, it works!  Here's a couple of pictures, it's not pretty at all. Needs to be mounted on something. 

Don KC9ZMY

Knack Story -- Tom WX2J

RTTY Model 15

Hello Bill,

Greetings from a fellow ham in Northern Virginia. I have enjoyed the SolderSmoke podcast for a few years now, and I just heard your recent presentation to the Vienna Wireless Society. We have a lot in common so it is about time I reach out to make your acquaintance.

I was born in NYC and grew up in Northern NJ. I was first licensed in 1969 as a high school student (51 years ago! Goodness!). My novice callsign was WN2JFX, and I progressed from Novice and then to General and Advanced as WB2JFX, and then eventually to Extra (in about 1990 -- while the 20 WPM code requirement still existed). At that point I put in for a 2X1 callsign and received WX2J, which is a nice twist on my original call.

I was fanatically active in my early years in ham radio. My Elmer (George, K2VVI, SK) set me up with a DX-40, and my parents provided a brand new Hallicrafters S-120 (you could copy the whole 40 meter band without changing the frequency!). I think I Worked all States as a Novice and learned that the human brain is the most amazing audio filter on the market. When I made General, George lent me an old Hallicrafters SX-25, and then I was really in good shape. Besides CW, I was also very interested in RTTY. I had my own Model 15 leaking oil in the basement and had a blast watching the magic of that thing printing messages out of thin air. I have always been a home-brewer, and one of the first serious things I built was a two- or three-tube RTTY demodulator from the Handbook. Aluminum chassis, chassis punches, tube sockets -- the whole works. I have no idea what the real inductance was of the inductors that went into the filters but somehow if the signals were strong enough, and on 850 Hz shift, it could actually demodulate signals. I probably still have that thing around here somewhere.

Another local ham bequeathed me his entire collection of 73 magazines - 10+ years starting with the first issue (~1960). I read them from cover to cover so many times I probably have them memorized. I became a real fan of Wayne Green, W2NSD, who was always ornery and controversial but a very interesting guy. I met him at a hamfest many years later and we had a great chat.

In any case I wanted to mention some other things that resonate with me as I listen to your podcast. As a kid growing up in the shadow of NYC in those years, you can bet that the Jean Shepherd broadcast was a regular part of our life. My dad used to listen to it every night -- 10:15 p.m. I believe, on WOR -- and we both used to greatly enjoy his stories of lighting up the fuse panel and nearly blowing up the house as he and his old man were playing with radios, etc. It was a common theme in our house too when my ham radio signal would blast into the TV set or I dangled new antenna wires off the house and out of the trees -- "You're going to blow this house up!" I studied electrical engineering in college and was commissioned in the Air Force upon graduation. I served a 20-year career in the Air Force and stayed somewhat active in ham radio. I was licensed and operated out of Okinawa (KA6TF) and England (G5ERE) during tours of duty in the early 1980s. Always an HF guy, in about 1982, in Japan, I bought myself a new Icom IC-720A, and this is still my primary rig. I was an early adopter of PK-232 and did some extensive building and experimenting with it. Sadly though, in the last 25+ years, my ham radio experience has mostly been vicarious as my work and family obligations have just not left much time for ham radio. I do have a G5RV wire antenna strung up but very rarely jump on the air -- sometimes during contests.

In high school we made a field trip to ARRL HQ in Newington, CT. While there we did all the things people do on such a visit, but one of the high points for me was meeting Doug DeMaw. I can just hear how Shepherd would describe it -- "I turned the corner and there he was! In person! The high priest of homebrewing! Doug DeMaw. In the flesh!" Cue the kazoo. I actually also met Shepherd at a book signing (Wanda Hickey's Night of Golden Memories?). I remember presenting him with a computer-printed banner of his callsign -- K2ORS -- produced by one of the few functioning computer programs I had written in high school. I also heard him on the HF bands one night -- I think he was in Florida -- and actually made contact with him, if barely being able to exchange callsigns can count as a contact.

Well, more than you wanted to know. I just wanted to let you know that I enjoy your podcast and can personally relate to very much of what you say. Although I am steeped in Hardware Defined Radio, I am also a software guy so I expect that my future includes SDR. I hope you and Pete are able to continue the podcast for a long time to come because I need the full HDR-SDR spectrum to be covered -- hi.

73,

Tom Fuhrman, WX2J

Overcoming the Complexity of the Michigan Mighty Mite: Walter's Sunrise Net Special

From Walter KA4KXX
June 21, 2020

Michigan Mighty-Mite:  Why So Complicated?

The April 2020 issue of QRP Quarterly magazine featured an article by Bob Rosier K4OCE which included a schematic for a “Ten Minute Transmitter” by G4RAW (SK), which apparently first appeared in SPRAT 82 in 1996. 
It is even simpler than the Michigan Mighty Mite, so this transmitter can truly be built on a solderless breadboard in about 15 minutes, because a complex coil is not required.  
The only tuning needed was for me to establish the correct value of the output series capacitor. 
This rig allowed me to check-in to the Sunrise Net (see details in blue text on my QRZ page) today on my very first attempt, and landed me a 549 signal report from 250 miles away.
The first photo shows the transmitter connected to a Transmit/Receive Switch mounted in an Altoids box. In the Transmit position the antenna is disconnected from my 1979 Heathkit HR-1680 receiver, which then coincidentally supplies a sidetone at an ideal volume level.  That little black pushbutton which can be seen in the second photo serves as my key, and works just fine for a five-minute daily QNI on the Sunrise Net.
Of course, part of the secret is having a crystal exactly on the Net frequency, and I have a few left, free to whomever in the Eastern U.S. is interested in building one of these simple Sunrise Net Special Transmitters and participating in our Net. 

SSB Transceivers of the 1960s --- Videos by Mike WU2D

I liked both these videos.  Mike WU2D really does a great job.  He covers a LOT of technology and theory in two videos.  Thanks Mike!