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


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

FCC to Ban Direct Conversion Receivers

From the FCC News Line:  

The Federal Communications Commission announced today that it will soon ban a wide range of communications equipment due to interference that this equipment is causing to Starlink communications satellites in Low Earth Orbit (LEO).  The banned equipment includes a range of legacy analog-type circuitry that, according to the Commission, has "lost relevance" and constitutes "an archaic electromagnetic nuisance."  Under the proposed Commission action, banned equipment will include all regenerative, super-regenerative, and direct conversion receivers.  

The interference potential of regenerative receivers has been known since the 1920s.  Direct Conversion receivers were thought to be less prone to Problematic Spurious Emission (PSE),  but in recent months  LEO satellites have experienced serious interference from terrestrial sources.  

An FCC official was nearly apoplectic when speaking about the devices that are causing this interference:  "They have no shielding.  They are built on wooden boards, and are made with superglue!  Heck, the main tuning device is -- get this -- a screw! A screw!  To think that something like that could threaten an entire LEO satellite system.  This is really unacceptable."  The official said that two persons in Northern Virginia had encouraged the construction of these "terrorist devices."  The FCC is working with the FBI and the Department of Homeland Security to bring these people to justice. 

The vast majority of the interference is believed to come from home-made ("homebrew")  direct conversion receivers.  These devices employ simple oscillators in the 7 MHz range.  The 85th harmonic of these oscillators falls in the middle of the UHF frequencies used by the satellite system.  The interference appears when the satellites are over areas known to be used by ham radio direct conversion enthusiasts.  There have been communications issues near Melbourne  Australia, the North Island of New Zealand,  Bali Indonesia, all across the U.S. (especially in the area of Nashua, NH), Canada, the UK,  Holland,  and Sweden. Recently there have been reports of interference from Argentina. 

A satellite company CEO of has been briefed on the matter, and promised to use his influence in the U.S. government to "squash this problem like a bug."  The spokesperson for a major ham radio organization in the United States reassured members: "Don't worry, commercial SDR transceivers will not be affected by this ban." 

What Homebrew Looks Like (And W9BRD comment on the High School receiver project)

Clikc on the picture for a clearer view of this fantastic image

Dave Newkirk is the son of Rod Newkirk, the guy who wrote the inspirational "How's DX?" column for QST for so many years.  Dave is obviously a very prolific and proficient homebrewer himself.  I really appreciate his comment on the High School receiver project.  Thanks Dave. 

Dave wrote on QRZ.com: 

Rummaging around the net for such phrases as "TJ receiver" or variations that include AA1TJ and receiver returns no solid hits, but by following clues I found a/the article with schematic at https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver. That's a well-thought-out design that'll provide fun, fun, fun.

I think I have something like 8 homemade receivers available at the moment at W9BRD, tube-based and solid-state, regenerative and superhet. all told covering 160 through 17 meters (if I include my tube-based and solid-state converters), and about the same number of homemade transmitters. With some exceptions for particular on-air celebrations and events, commonly my entire station lineup is homemade from stem to stern, so to speak.

I've been building radio gear since 1968. Here's some recent fun:

Zed thread covering the development of a converter-plus-regenerative-tuner combo that I came to call the "Super 3-in-9":

https://forums.qrz.com/index.php?th...ceiver-using-one-9-pin-miniature-tube.897249/

Zed thread covering construction of my version of a coffee-can-based receiver/converter combo my father used for 15ish years as his main station receiver after beginning its construction in 1951ish "on a kitchen table in Hartford" while working at ARRL HQ:

https://forums.qrz.com/index.php?th...building-a-160-meter-coffee-can-regen.938709/

To which discussion our own @N2EY kindly posted the mid-1960s "How's DX?" lead in which Dad laid out his station design/configuration/construction philosophy ( https://forums.qrz.com/index.php?th...0-meter-coffee-can-regen.938709/#post-7021505 ).

To us, commercial/mil/pro gear has been and always will be various shades of inspiring to fabulous, but only with homemade gear are we home.

A little Night Radio Romance at W9BRD, featuring the BRD-160CC 160-m regenerative receiver and converter (transmitter and antenna tuner not shown). 

Jim, WB5UDE's Knack Story

Hi Bill! ...

Of all the Amateur Radio related podcasts I've sampled, SolderSmoke has

been my favorite.  The reason is because of the passion you (and Mike,

too, in the beginning) bring to us each and every episode.  I've been

passionate about radio since I was 10 years old, and electronics in

general since I was about 8.  Many of the other podcasts seem to lack

this quality, or worse, try to have a "how to do things in Amateur Radio

the right way" focus.  I suppose their thinking is that hams listen to

podcasts to learn, so they assume their job is to tell someone how to

get started doing this or that.  However, the result often comes off

being preachy-- that there is a Right Way to do things, and that it's

important to do things that way, so they'll work out best.  That's not

what Amateur Radio is about!  Amateur Radio is about doing something

because you're passionate about it.  Even where your own passions are

concerned (e.g. individual analog components, no chips!) you acknowledge

that the other approaches are equally valid, and that we should all

do what we enjoy.  You're not shy about branching off into your other

technological passions, about space, RC aircraft, etc., which as you

rightly observe, so many of us have in common.

We share a passion for learning and understanding about radio/electronics.

Where we differ is in the depth of understanding we crave.  Actually,

I have experienced enough of that desire for total understanding to know

exactly what you're talking about, but I'm usually content without it.

I realized back when I was a teenager that some things would click for me

right away, and some others, I'd always struggle with.  I made peace with

that very early.  Still, I have wondered more than I could find ultimately

adequate explanations for about things like, OK...exactly what ARE these

radio waves?  More often, though, I am content to gain a sufficient depth

of understanding that I feel comfortable knowing how I might achieve a

particular thing.  I have great sympathy for your struggle with "holes" in

transistor theory.  That actually clicked for me, but not immediately--I

had to chew on it just a bit, but then it did gel.  If that "?" floating

over my head had refused to disappear, I might have found that a little

frustrating.  But to me, the really frustrating thing is that books so

often begin by talking about electrons and holes and depletion zones and

so forth.  I have found that a much simpler explanation is sufficient

for my tastes--I'm content to understand that there are N-doped and

P-doped sections, and that this allows the silicon to control current

in a certain way.  Knowing how we arrange the electronics around a

transistor to get it to behave in its own useful way in a circuit is

really all I've ever cared to know.  And furthermore!... I'd rather

have the whole presentation be top-down...I'd rather start with what a

transmitter and receiver are, and what their stages are, and what kind of

circuits go into those stages, then eventually, down to what components

make up those circuits.  It's all a natural progression, for me, of, "OK,

I understand that--now, how exactly does that part work?  Give me more

details, please."  The whole thing of just learn all these fundamentals,

and we promise we'll eventually tie them together into something useful

doesn't work well for me as a way to learn.  Worse than that, it doesn't

thrill me to the core the way gaining a gradually deeper and deeper

understanding does, as I drill down into more and more detail about

things I've caught an interest in, and remain content with a shallower,

surface knowledge of things I just want to know well enough to use,

when I need them.  So, I don't have the same burning desire to get down

to the bottom foundation in first principles all around that you do,

but I do love to learn, and understand.

I got my start in electronics when I was eight years old, and read a

book my parents had bought me about electricity.  I suddenly realized

that things like flashlights and motors didn't have to be a strange

mystery, but were things I could understand, and even try for myself.

I began reading everything I could find at school about electricity.

Meanwhile, over the next couple of years, I began appreciating music.

Reproducing music was something very special that electronics could do.

Even more special, radio electronics could bring you this music from

far away.  That whole combination, bringing communication from far away,

including things I found enjoyable, and doing it with this wonderful

magic of electricity, which it was possible to actually understand, was

(and still is to this day) quite thrilling.

When I was ten years old, I realized that, lo and behold, it would

actually be feasible for the amount of money my parents would be able

to spend for a Christmas present, to buy a pair of toy walkie- talkies.

I set a new level of obnoxiousness leaving the catalog open to the

page with the walkie-talkies, and finally, just flat out telling them

that's what I wanted.  I then exceeded that level of obnoxiousness when,

I'm ashamed to say, I absolutely chewed them out when they didn't take

the hint.  Instead, I got a tape recorder.  I actually enjoyed that, too,

but continued to campaign for the walkie-talkies, and when I still wanted

them a year later, my parents decided I meant it, and bought them for me.

(My dad knew a thing or two about radio himself, and my mother later

told me that my dad had been concerned that the walkie-talkies would be

fragile, would perform poorly, would chew up batteries like you couldn't

imagine, and would have a very disappointingly limited range.  He was

right about all those things, but it turned out I was right, too--in spite

of all that, I loved those walkie-talkies as much as I'd known I would.)

Meanwhile, I got a 100-in-1 electronics set for my birthday.  My parents

had wanted to find one that was about individual components, but all

they could find was one that was based on projects using a pre-built

audio amplifier, radio receiver, speakers, and battery holders.  Its only

component-based aspect was an apparent afterthought, an AM BCB transmitter

built on a cardboard circuit board.  This was really a bit too "appliancy"

for me--I would rather have been learning how to make components work--but

I still learned a lot from that.  I also bought an AM clock radio for

less than a dollar at a garage sale.  It didn't work very well, but this

was really good, because I learned that I could make it work much better

by wrapping a few turns of wire around its built-in loop antenna, and

attach that to various antennas I got to experiment with.  Months later,

I found a very nice tube-type AM/FM Zenith table radio at another garage

sale, and bought it for $5.  That radio went home with me strapped to

the back of my bicycle, then went on the bookshelf on the headboard of

my bed.  I learned to work its knobs backwards, reaching behind my head.

I listened to AM radio stations from all over the US until all hours of

the night, and my addiction to radio grew even deeper roots.

Then, when I was 13, I found a Zenith Transoceanic portable at a

garage sale, for $15.  I raced my bicycle home as fast as I could.

(This radio was a little too big for the bicycle.)  I got my mother to

drive me back there (urging her to hurry!  before someone else bought it),

and brought that one home....  then spent that whole evening driving my

parents nuts by running into the room where they were every few minutes,

excitedly exclaiming something like, "and NOW I'm getting a station from

GERMANY!" and then running back to see what I could get next.  Of course,

I had even more fun with it after I put a decent outdoor antenna up.

When I was 16, I finally met an Amateur Radio operator.  I'd read an

ARRL book about becoming a ham, and building one's own station, but the

books were a little expensive, and I wasn't sure how to go about it all.

Pat Barge, WB5OEB, about one year older than me, had earned his license

about a year before, and was eager to pass along the favor of showing

the ropes.  I got to listen as he operated his station, and he told

me which books would give me the specific knowledge I'd need to pass

the tests.  I was 17 when I got my first license.

While I was learning what I'd need to get my first license, I got my

next great receiver--this time, an RAL-7 regenerative receiver.  You and

I very much see regenerative receivers differently, but then, I had

the pleasure of learning on the best regenerative receiver ever made.

Back in those early days, I'd sometimes hear the opinion that the RAL-7

was not merely the best regenerative receiver ever, but the best receiver

ever, period.  I think all those old-timers have died off, though.

I've enjoyed building a bit over the years, too.  I haven't found nearly

as much time for it in my adult years, so I think to this day, about

half of my building was done as a teenager.  I haven't done anything

impressive, but I have made contacts using things I've built myself, and

what a thrill that is!  I've built more than a dozen projects (but fewer

than two dozen).  The most fun I've had was several years ago, following

the advice of a post to the Glowbugs list, I began experimenting with

crystal radios, then slowly began to ramp the circuits up, adding tube

amplifiers, tuned circuits, etc.  My favorite successful project was

a SWL converter to feed a car radio.  I built a doubly balanced diode

ring mixer and a crystal oscillator.  I used a 3-gang air variable

as the foundation for a 3-stage front end filter.  I had an 8.x MHz

crystal that put signals from (depending on where I tuned that 3-gang

air variable) either the 49 m or 31 m shortwave broadcast bands in the

tunable IF provided by the AM car radio, which fed a nice 3-way speaker

from a stereo, for the most beautiful sounding SWL listening of my life.

Like all my projects at that phase, it never left the breadboard stage,

but it stayed on the breadboard for a long time, while I paused in my

building to enjoy listening for a while.

I serve as one of the net control stations for a local two meter FM net

that meets weekly to discuss technical topics.  We got our start back

before most folks had Internet access, and served a very useful role as

the place where hams who had a problem to solve or wanted to ask how to

get started in a new phase of Amateur Radio could come and get answers to

their questions and ideas about how to do things.  In these days where

it's easier to Google for answers, we've morphed into more of a general

discussion session among a small, dedicated group, but it's still a lot

of fun.  It gives me a chance to do what I enjoy the most consistently

in Amateur Radio, which is to understand, talk about and explain things.

In fact, that's often all I find time for.  Other than the weekly net,

I sometimes go a long time without actually getting on the air.

When I do get on the air on HF, it's almost always CW.  I've always

struggled with Morse, which has never come easy to me, but I enjoy it.

Every time I return to HF after having been away for a while, I think,

"This time, I'm going to do some SSB" but every time I actually sit down,

I think, "But tonight, I'm going to do CW."  I can't explain why I like

it better, but it just seems to me to be a particularly special part of

the magic of radio.

Before closing, I'd like to finish by responding to something you

mentioned in episode 162.  You told about a member of the audience at a

talk you gave, who was asking about how much time it had taken you to

build a particular radio, seeming to suggest there was a price to pay

by investing all that time.  I love to explain to people that there is

a whole different economics to Amateur Radio.  In my professional life

in IT, I'm always promoting the idea that we should deploy and install

systems so that we will expect them to work trouble free throughout

their anticipated lifespan.  People balk at the expense of doing it

that way, but it's my job to remind them that the cost of having it

fail, in lost productivity, is far greater than the expense of doing

it right in the first place, not to mention the fact that coming along

later and remediating an inadequate deployment usually costs more than

it cost to do it wrong the first time, let alone the incremental cost of

doing it right.  Similar ideas prevail with radio.  We see professional

radio installations where many thousands of dollars are spent doing

things that we hams rarely even consider.  For many of us [raises hand]

we must do Amateur Radio out of a meager budget for entertainment,

or not at all.  But even more importantly, if we enjoy doing these

things, then the time spent laboring at our projects--transmitters,

receivers, antennas, etc.--is not a liability at all; it is an asset!

If assembling a kit, or planning and building some unique project, or

putting up a different antenna every six months, is something we truly

enjoy--even LOVE doing--then that time spent is no hardship at all.

Thanks, Bill, for the time and effort you put into providing us with

an episode of SolderSmoke from time to time.  All my life, I'd wished

for TV and radio shows about Amateur Radio, and now, they're finally at

my fingertips.  Your gift to the hobby is deeply appreciated.

73,

Jim  WB5UDE

Super-Regeneration is Super-Strange

Farhan VU2ESE is largely responsible for this.  He has recently been talking about VHF.  (More about this in due course.).  This started me thinking about my failed effort in London to get on 2 meter AM.   My plan was to use the transmit portion of this HW-30 (above) with a 2-to-10 downconverter and my trusty Drake 2-B for receive.  

Tony G4WIF also bears some responsibility:  When I expressed interest in Farhan's VHF work, Tony sent me two articles from SPRAT.  Both of them were about super-regenerative receivers.  

Farhan's comments caused me to pull the HW-30 out of storage.  I started poking around the transmitter.  But then I noticed something:  On receive, the AF amplifier was obviously working.  Then, when I tuned through the 2 meter band, the rest of the receiver seemed to be working too.  I fired up the HP-8640B sig gen on 2 meters and turned on the AM modulation.  Indeed, the old receiver was inhaling!  

This launched me into an effort to understand how super-regenerative receivers work.  There are a lot of really weak explanations out there. You get the distinct impression that the person explaining the circuit does not understand it himself.  This makes explaining it very difficult.  I am not the only one to notice this phenomenon:  Mike WU2D commented on this in one of his excellent super-regen videos.  This one:  

https://www.youtube.com/watch?v=QOhNPLT8R10

Mike very kindly said the operation of this circuit seems like "magic."  I was thinking more in terms of Voodoo.  

Howard Armstrong discovered super-regeneration years after he invented plain old regeneration.  The new discovery came around 1921.

It looks like VHF guru Frank Jones had very early misgivings about super-regeneration.  In his 1934 classic 5 Meter Radio Telephony, Jones seems unenthusiastic about the circuit and about our ability to understand it:  "To explain, simply, exactly how this form of detection takes place is not a simple matter, but some of its characteristics are easy to visualize."  In this book, Jones goes on to predict that super-regens will be superseded (!) by superhets.  Indeed, in his 1961 book VHF for the Radio Amateur there are no super-regen circuits; all the receive systems are down-converters to HF receivers. 

Still, with that HW-30 hissing away right next to me, I feel I need to understand how the super-regen works.  I'm not there yet, but I'm trying.  Here are some good resources: 

A good article from Wireless World 1946:  

http://www.r-type.org/articles/art-285.htm  

A student's write up of his effort to understand: 

https://folio.brighton.ac.uk/artefact/file/download.php?file=597679&view=111191

But the best so far (for me) is from Frederick Terman (one of the founders of Silicon Valley) in  his 1943 classic Radio Engineer's Handbook.  Click on the images for a clearer view. 

I will definitely try to get the HW-30's 5 watt AM transmitter going.  I am not so sure I'll do anything with the receiver.  I think this is a matter of picking your battles and "finding joy."   I didn't find joy in FT-8, so I stopped working with it.  Same with my HA-600A, DX-40 Novice rig.  Same with CW in general.  And the same with SDR.  I suspect that super-regen receivers may also fall into this category.  I mean, let's face it, if you are not fond of ordinary regens, is there any real chance that you will like SUPER-regens?  Even Frank Jones seems to have disliked them.  And there is a reason Howard Armstrong moved on to superhets -- they are better! But still, that receiver is hissing away at me...  Stay tuned. 

Haunted by the Gong (Ooooo that's Awesome!) Donald's Knack Story

Bill:

 

First off thanks for the wonderful podcast. I only just discovered it and I have loaded as far back as I can go on my Phone. I have been listening to it every waking moment. Though I fear that even at one or 2 a month no amount of commuting, dishwashing or bathroom cleaning will allow me to catch up with you. 

  I so identify with your idea of the Knack. I was forever taking things apart, my mom had to remove anything that could be used as a tool from her home for my first few years as even at age 2 I was into clocks, cabinets and basically anything that wasn't nailed down. Until your podcast I hadn't even heard of the International Geophysical Year, but discovered I missed it by only 3 months being born in March of 59. I do think though that those of us that were even a little knackish were encouraged on our way by the Space program. 

  Even though I grew up in Canada, I was riveted to the TV for every space launch, touch down or space walk. Many of my first memories are watching grainy broadcasts from Gemini and then on to Apollo. Even now I stayed up to watch the Mars rover land those few years ago. 

  Radio was always a special interest for me from the First Short wave radio I got from my grand father. I remember discovering WWV, BBC VOA and the Netherlands english language programming. This of course launched me into a frenzy of stringing wires higher and higher much to the chagrin of my parents. My poor dad that was an arts major didn't know what to think of me. 

  I'd always wanted to get in to ham radio but the code requirement held me back. My dyslexia kicked me really bad. I had the little tapes from radio shack and I'd work and work but got no where. So i resolved myself to just shortwave listening. 

  I was laughing when you talked about your relationship with Regenerative Radios as one of the first radio projects I built was the "Science Fair Globe Parol Regenerative Radio" From radio shack. Here is a link to the thing http://www.ohio.edu/people/postr/bapix/rsglobep.htm I still have it at my mom's house. The last time I put batteries in it it would at least get WWV. Which is no small feet when you realize I built it with one of those Weller Soldering Guns that you could reseal canned goods with. I'm sure if I opened it up now there'd be blobs of solder the size of Cicada's in there.  

  I was just listening to Episode 147 where you were talking about the All American 5 tube radio. I must have tore down 20 of those things as a kid. Your Right they were dangerous as anything you could get. Most of them the chassis was hot if the plug was in wrong and there wasn't like a fuse or any safety equipment in there to stop you from hurting yourself. Yes they were cheep and made so without a transformer, and all the tube heaters in series with the panel bulb for a bit of protection to prevent a surge on power up. But one other feature they had was that when they were originally produced there was still some DC mains power around and they would run if you put in the Plug the right way. My old electronics teacher claimed that you could run them off 3 45 volt batters on the Farm in a pinch. Though 19 40's battery technology I'm not sure if that was a practical solution. Though In High School that's what we had to learn. Learned to tune, debug and repair those puppies. 

  After high School I went into the phone company and later made my way as a lot of us Knackish people in to the computer/software industry. And low and behold after about 30 years they dropped the Code requirement and now living in the States I went out and finally got a license. 

  I just wish I had found your podcast sooner as I would have done things a little differently. However I have managed to do some serious kit building. I have built two TNC's, one for the beaglebone and one for the Pie. I have built one softrock receiver and another Softrock emsamble  RXTX that I'm just trying to figure out how to make work. I also built though it's not really a kit a Kx3 that is my main HF rig. 

  I thought I was really interested in the computer radio connection but wow when I see what you have done with the BITX and the manhattan build I'm thinking I want to build a rig that maybe I can run some JT65 or PSK31 on. I know what you mean about the Phone and SSB but right now stuck in the city of Chicago my antenna space is limited and i'm surrounded by power poles so I have a lot of noise no matter what I do. 

  One thing I need to talk to your buddy Pete as in the left over spare time I have, between work family and radio I'm trying to complete the BSC that I never did during my misspent youth. But I'm stuck at the final project. I need something that needs some code and could be written up as a research paper I keep thinking there has to be a radio project here somewhere. 

  Anyhow that's enough I'm sure you get lots of people with their stories but I thought a little of what I encountered might be interesting. I really appreciate the podcast love all the personal stories combined with the tech talk. Keep up the good work. I'm looking forward to getting current. 

   Donald L. Gover KC9ZMY

P.S. I have woken up twice as of late thinking I heard a Gong followed by "Oooo That's Awesome" Maybe I'm listening a little to much :) 

 

P.P.S  Again catching up on the podcasts though my podcast listening time is a little reduced as I bought your darn book that's very interesting! But I wanted to make sure that I did inform the Knackers Union, whom I believe that Steve Snort Solder Smith is the enforcement officer that I had already constructed my 40m low pass from 4 state QRP. I have provided photographic evidence of it's construction and promise not to QRP on 40M without it. 

 

 

When Your Local Oscillator Could Sink Your Ship!

Thomas KK6AHT is the intrepid radio amateur from France who moved to California and successfully built a Minima as his first homebrew project.  Yesterday we got additional evidence that Thomas definitely has THE KNACK.  It seems that he has been looking through really old radio magazines (clearly a symptom).  He sent us this add from 1942.  Yikes!  Imagine getting your ship sunk because your Local Oscillator is not quite local enough!  

.....................

Hey!

I thought you would get a kick out of this 1942 ad. Sounds like those guys had a some good reasons to fight QRM ... Who knew the important role played by the FCC during the war?

Now tell me: why were the receivers so noisy at the beginning of the war? What did they change? Happy new year to you both! May the gods of radio (and digital) bring you much fun on the air.

73, Thomas  

..............................

Good to hear from you Thomas.  Long time no hear -- I was beginning to fear that you had grown disillusioned with homebrewing and had switched to stamp collecting or something else less frustrating.

As for the ship radios, two things come to mind.  Some of them may still have been using regens at the start of the war.  If so, that was kind of suicidal -- regens radiate!  The detector moves in and out of oscillation (sometimes staying in oscillation) at the receive freq.  The Germans were quite good at detecting and direction-finding these signals, on land and at sea.   So the regens would have to go.

Superhets are not quite as bad, but they too can radiate.  My Bitx spills out a bit of signal at 23 MHz (VFO) and at 5 MHz (BFO).  Without adequate shielding, these sigs could also be detected and triangulated.   Looks like the radio in the picture had lots of shielding. 

We watched a French movie last night:  The French Minister.  A comedy about life in the French Foreign Ministry.   It was kind of fun.

What are you working on?   I am listening to 17 meters using an OLD superhet in which I have replaced the VFO with an Arduino/DDS generator.   Works great but the display is making lots of noise. 

73  Bill 

..................................

Hi Thomas,

Well Thomas, I will dip my toe into some very deep water and attempt an answer for you which also is an important clue about QRP operations.

1. Today we have many many signals co-existing in the radio spectrum. During the war there was much less radio garbage and the military lit up the ether with transmissions very sparingly. But that is on the transmit side. That said the local oscillators (much like you have with the Si-570 on your Minima) used in receivers also produce RF that unless is minimized in some fashion is passed right through to the antenna and can be detected. Regenerative receivers are especially prone to this. Yes some military equipment used regenerative receivers. In fact the famous Paraset had to be constantly moved so it would not be detected.
2. This receiver generated RF into the antenna was addressed by companies like Scott by shielding everything. That receiver in the photo probably weighed about a 100 pounds or more. Much attention was paid to RF bypassing and grounding. The cheap table top radios were RF generators par excellence.
3. There was another approach developed in WWII to solve that problem and forms the basis of what makes work that little device sitting in your pocket. The odd part it was invented by a famous movie star. Look up Heddy Lamar in wikipedia. She and a co-inventor came up with the concept of frequency hopping and spread spectrum technology. By jumping frequencies it would be hard to pinpoint a transmitting station. That concept forms the backbone of our cellphone system
4. Now the QRP part – if the RF output from a receiver local oscillator (milliwatts) can be detected from afar – then it follows QRP works!

Have fun. 

Pete

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

Book Review: "Man of High Fidelity: Edwin Howard Armstrong" (Free Download)

Dave W2DAB sent me this wonderful book.  He picked up a copy at a recent Columbia University lecture on E. Howard Armstrong.  Written by the notable science writer Lawrence Lessing, the book was first published in 1956.  The paperback copy that Dave sent me came out in 1969; while 50 years old, my copy is in remarkably good shape. 

I really liked the book.  The author captures the technical achievements of  Armstrong, while also describing vividly the world in which Armstrong lived.  Being from the area, I especially liked Lessing's description of New York City and the Hudson Valley in the early years of the 20th century. This was the world of my grandparents; Lessing's book helped me understand it better. 

For the radio amateur, I think the most gripping part of the book is the way Lessing describes  the excitement of early radio.  Armstrong was a true enthusiast for the new technology, and he was -- even as a teenager -- at the cutting edge.  He was constantly striving to improve the technology, especially the receivers.  Like us, he often became obsessed with his radio work, often forgoing sleep and missing family meals as he toiled away in his workshop. Lessing tells us of Armstrong's astonishment and joy, when, upon inventing the regenerative receiver, he was suddenly able to clearly receive signals from distant stations that previously had been barely discernible.  Realize that when he was doing that, he was the only person on the planet who was doing it.  He was the inventor. He was the first. 

Lessing gives us a lot of great information about Armstrong's work as an officer in the U.S. Army Signal Corps in Paris during World War I.  We learn more about how his desire to be able to detect noise from the electrical systems of enemy airplanes led him to the invention of our beloved superhet receivers.   But my favorite Armstrong in WWI story involves his visit to the radio shack of the ship that was carrying him to the war.   In the radio shack he found a conventional station.  But he asked the operator if he happened to have one of the then new audion tubes.  On the spot, Armstrong took the tube and rigged up a regenerative receiver.  He and the ship's radioman then delighted in hearing stations that had never before been audible.   Amazing.     

I was less interested in the sad tale of Armstrong's legal patent battles, so I kind of skimmed through that.  I'm also not much of an FM guy, so I'll save those portions of the book for a later date.  

I think this is an important book about a significant part of radio history.  It is well written.  It gets almost all of the technical details right (but sorry Mr. Lessing,  radio waves are not composed of electrons).  The book deserves a place on the shelf of all radio history libraries.   If you can't get a print copy, an online version can be downloaded here: 

 https://archive.org/details/in.ernet.dli.2015.189098

Thanks again to Dave W2DAB.   

G.W. Pierce and the AA1TJ GiGi

Mike, AA1TJ, continues to provide the global solder-melting fraternity with large doses of QRP/homebrew inspiration. And, as usual, his latest series of messages to QRP-L contain interesting references to the radio pioneers who laid the ground work for his low power exploits. This time, it was G.W. Pierce.
-------------------------------------------------------
From AA1TJ on March 8, 2010:

Fellers,

It was an exciting QRPp afternoon here on 20m. It started off well
with a ten minute contact with G3MJX. Tony was running 5w to a dipole.
I'm still using the breadboard, two-tube, 250mW (Gigi) station that I
wrote about last week.

KB0PCI in Minneapolis was my next contact. Wayne was using 5w to an
indoor loop. I thought that was pretty cool.

Things seemed to be going so well that I felt the urge to further
reduce my output power. Dropping back to 56mW, I soon snagged Jack,
W7CNL. He's out in Boise with 5w and a five-element Yagi. It was a
great contact with 579/539 reports.

After we signed I resumed calling CQ. Sometime later I heard my call
coming back at me; always a happy moment when you're running QRPp. But
wait...he's signing DH1BBO...Holy Toledo!

With a pounding heart I sent off a 559 report. Olaf came back with a
529 for me, and get this...he says he's running 300mW to a windom! The
first round was an easy copy for both of us, but thing got a little
rougher after that. Still, we were able to hold it together through
the finals for a complete QSO.

Again, my transmitter circuitry is right out of 1928; a
crystal-controlled, push-pull oscillator using a single, 3A5 (a
twin-triode introduced by RCA in 1942). The receiver uses a second
3A5. The first triode forms a crystal-controlled autodyne converter.
The second stage is a standard regenerative detector driving the
headphones directly. My antenna is an end-fed wire at 35'.

Anyway, it was one of those QSO's that I dream about; QRPp on both
ends from start to finish, wire antennas at both stations and an
ultra-simple rig from the days of yore. It was Olaf's first QRPp DX
contact ever, and 57mW now stands as my lowest USA-to-Europe contact
power (230mW was my previous best).

As for working a 300mW German station with a receiver made from a
twin-triode; I think it's a testament to what these little
regenerative detectors are capable of. I was awestruck at the age of
12 or 13; having built my first genny. I love 'em no less some forty
years later as they truly are a beautiful technology.

73/72,
Mike, AA1TJ


From AA1TJ on March 3, 2010:
Bill,

Gigi worked AA7VW (running 5w to a Moxon) in Oregon today with 250mW.

I've been reading a bit of history here in preparation for my
presentation at MassCon next week. For example, I've traced the
crystal-controlled, push-pull transmitter (used in Gigi) as far back
as 1928. Cady and Pierce did their ground-breaking work on quartz
crystal-controlled oscillators in 1923, so it didn't take long for
hams to jump on this one. BTW, Professor George Washington Pierce
("G.W." to his friends) was a real character!

I send my best wishes to you and the family, Bill. The sap has just
started flowing here this week. It's Maple sugaring time in Vermont
again. Spring can't be far away now.

73/72,
Mike, AA1TJ

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

Here is a bio on Pierce: http://profiles.incredible-people.com/george-washington-pierce/

This all makes me want to reconsider my opposition to regens... Maybe they are NOT possessed.

Mike WU2D's Video on the SimpleX Super Receiver -- Part II

 Another FB video from Mike WU2D.   

But you know,  I too find myself kind of opposed to front panel on-off switches.  I power my rigs with small DC supplies.  I just turn on the supply when I want to use one of the rigs.  I don't have or need a switch on the front panel of the rig.  

I especially liked Mike's use of the gate dip meter and, of course, the Q meter.  FB OM. 

I must say I have a preference for the first version, but only because I dislike the regenerative circuit in the second version.  I do like the newer-style coils -- I have one in the BFO of the Mate for the Mighty Midget receiver.   

Thanks Mike for the sideband inversion factoid in Part 1!   The Hallas Rule -- words to live by. 

One word of caution.  I used 6U8s on my Mate for the Mighty Midget receiver.  I had good results, but WA9WFA had a lot of trouble.  We eventually concluded that the 6U8s didn't age well.  And they were quite long in the tooth.  We found (from the tube guys) that 6EA8s aged better and were a good and easy sub for the venerable (perhaps TOO venerable) 6U8s.  I switched tubes in my rig and it did seem to work better.  BTW, this is the receiver that I use to listen to the Old Military Radio Net on Saturday mornings.  

Here is the story of our switch from 6U8s to 6EA8s: 

https://soldersmoke.blogspot.com/2022/02/6ea8s-in-mate-for-mighty-midget-and.html

AA1TJ's Nifty Fifties Pixie

Once again great things are happening in the underground lab of Michael, AA1TJ. Michael has temporarily put aside his work on Iron Pyrite-based receivers, and is now working the world with 50's era point contact transistors. I can feel the enthusiasm, even all the way over here in Rome. I particularly liked Michael's description of the QSO in which the other guy heard his backwave. Backwave is the very small signal that is sometimes put out when the key of simple transmitter is up. For example, the oscillator on my old VXO-controlled 6 watter (from "QRP Classics") ran all the time -- I just keyed the amplifiers. Sometimes guys would report hearing some of the RF from the oscillator even when the key was up. (By the way, the term backwave reminds me of a word used sometime by Billy and Maria: backwash. As in, "No Maria, you can't have a sip of my soda -- you always leave backwash!")

In his e-mails, Michael mentions that the physics of the point contact devices are a bit of a mystery for him. I recall that the book "Crystal Fire" by Riordan and Hoddeson had some pretty good info on how these early transistors worked.

Here are some excerpts from Michael's e-mails on this project:

I haven't had time to document this pyrite/tunnel diode receiver on account of a phone call that I had two weeks ago from Jack Ward at the Transistor Musuem. Jack approached me with an idea to recreate the first ham radio contacts using transistors. Of course, the point-contact transistors involved are now pretty rare items. No problem for a fellow with a transistor museum though!

Jack kindly sent me a couple of Western Electric, 2N110 "relics." I had some initial trouble with "squegging," and I wasn't able to produce oscillation above 380kHz. To read a recent tale of one fellow's trouble trying to tame the 2N110, please see

http://homepages.nildram.co.uk/~wylie/GEC/radio/article.htm

I especially liked where he wrote, "I did seriously consider giving up at this stage and taking up heavy drinking." ;o)

However, I located an old textbook that discussed circuit design theory using point-contact transistors (the physics of these devices are still clouded in mystery). What I learned made all the difference. A few more hours at the bench and I had an 80m transmitter putting out 10mW.

The story gets better though, Ned. A circuit briefly described in another old book really caught my attention. It was pretty much the same circuit as was used by George Rose, K2AH, in his first transistor QSO. Only, a circuit (designed by G3IEE) showed a pair of headphones in dotted lines, next to the collector resistor. The text merely said

"As indicated, the circuit also functions as an oscillating detector type of receivere for local continuous wave operations whith head phones plugged into the collector circuit instead of resistor R3. Good reception and break-in operation were obtained."

That got my blood moving! Positive results came right away on the bench. The received signals were every bit as strong as with my Reggie and the Cub Scout heterodyne (what I started calling, "Chester," after the name of the mine where the pyrite was found).

I had my first QSO last week using Jack's point-contact transistor (made in 1956) in the transceiver designed by G3EII (in 1954). Jim, W1PID, was my first contact. Since then I've made over a dozen QSO's with five different stations.

FYI, I'll paste a message below that I sent to Jack Ward this weekend. One thing I forgot to add is that W1VZR copied my 10mW signal on his Cake Pan regenerative receiver over in Maine last week. Aside from my three QSO's with VE3DJX at a distance of 319 miles, the other notable results to-date were hearing both W1DFU and W1PID - in the course of separate QSOs - when they dropped down to an output power of 100mW.

Again, I haven't had a chance to post much on my web site, but I do have the current schematic up, and you can see both K2AH and G3IEE's circuits in scans from the old transistor book. G3IEE's circuit is shown in Figure 16.2 in the second jpeg image.

http://mjrainey.googlepages.com/projecttransistorqsoii

One more thing, Ned. I hooked up this past week with G3JNB. Victor was one of the fellows (he was only 21 at the time) working with Tony, G3IEE, back in 1954 to make the first-ever, UK ham radio QSOs using transistors. Victor has already posted an envelope containing copies of his log, the QSL card from G3IEE and the original, 1954, Wireless World article describing their results. In the course of our Skype video call last week, Victor held up to the camera the RAF telegraph key that he used for his QSO with Tony. Pretty neat, eh?

I've got to get back to work here. Congratulations on getting your Reggie up and running, Ned. I look forward to seeing the photos and I'd surely like to hear about any contacts you make with it. Speaking of which, I have some photos of Jim, W1FMR's beautifully constructed Reggie that I've been meaning to post on my web page. Once I get around to it would you mind if I include one of your photos as well?

Best wishes,

Mike, AA1TJ

Hi Jack,

Yes, I had great fun with our little 2N110's this past week. Of of now, I've had well over a dozen radio contacts with five different stations. I used 10mW of output power to make these contacts. The distances shown are all "as the crow flies."

W1PID, Sanbornton, NH, 67miles; lowest power used on his end 100mW
VE3DJX, Smith Falls, Onatario, 319 miles; 10watts on his end
W1DFU, Wallingford, VT, 42 miles; his lowest power was 100mW
W1VZR, Limerick, ME, 100 miles; 40w

Pete, the last fellow listed, heard the 2N110 while it was running as a "beacon" with a continuously looped Morse code message. Having received my call-sign he located my email address and shot off a reception report. I saw his message pop up on my computer and quickly looked up his telephone number. He was still at his radio when he picked up the phone. I found him pretty excited as my signal strength had sharply risen in the last few minutes. He asked if there was a problem with my keying circuit as he could still hear a faint tone on my frequency when my transmitter should have been silent. "Ha!" sez I, "You're hearing a 100 microwatt back-wave radiation!" The distance separating us divided by the 100uW power is equivalent to 1 million miles per watt; a very impressive figure!

One more station answered my CQ this past week from near Hartford, CT. However, I can't recall his call sign and I'm currently at work but my logbook is at home. My output power was up to 17mW during that contact; on account of a temporary change that I made to the circuit. However, pushing the transistor to that power level reduced the quality of the keying, and so I returned to 10mW following that contact (earlier, I'd reported that my output power was 12mW, but a more careful measurement indicated that I was only putting out 10mW).

You might have noticed that I've posted the schematic to my web site. However, I expect the circuit will change over the next week, or so, as I still want to tinker with the keying circuit. By all reports my signal is good but it has just a touch of keying "chirp." Chirp is what hams call a variation in the received signal tone when the telegraph key is first depressed. Again, I expect to have that sorted out before long.

Yes, it was a real pleasure talking with Victor, G3JNB. FYI, I'll send you copies of all the documents that he provides. He said that he's including some original data sheets for point contact transistors that he's held on to these past 55 years. I'll keep copies and send the originals to you.

I asked Victor if he'd like me to build a duplicate radio for him using the second 2N110 that you sent me. I think he was thrilled to hear my offer. Don't you think it would wonderful if he, of all people, managed to make a contact using a reproduction of the point-contact transmitter that he and Tony, G3IEE, used in those pioneering days?

The order of business next week is to finalize the circuit design and begin building two identical circuits into permanent radios. Of course, I'll take time off, now and then, to try and make more contacts. I'm already astonished that it was possible to span a distance of 319 miles (not once, but thrice!) using your ancient transistor relic.

Acting on your suggestion, I looked up the other fellows mentioned in K2AH's article. It turns out that Tommy Thomas, W2UK, was quite a radio pioneer on VHF.

http://www.infoage.org/html/p-43W2uk.html

Unfortunately, I've learned that he passed away not so long ago. The call signs of the other two fellows are not currently in the FCC database (I suspect because they are gone as well). A quick search on the Internet turned up nothing on them.

Victor, G3JNB, remarked that he believes that he is the only one left of his original group of transistor enthusiasts. Doubtless, one reason is that he was only 21 years-old at the time of the experiments with G3IEE.

Victor reports that Tony, G3IEE, worked as an engineer for Mullard. I guess that explains where his transistors came from. Victor used a standard vacuum tube transmitter for his first contact with Tony, but sometime later he built his own one-transistor transmitter following Tony's design. Victor says that he used it to make one or two contacts across town before he put it on the shelf. Again, I'll be very interested to see the photocopy of his station log from that period.

One more thing, Jack. I'm fortunate to count George, G3RJV as a pal-o-mine. George is a recently retired Anglican vicar, but he also founded the GQRP; what began as a society of UK amateurs interested in low power operation. Since then, it has become something of an international institution. I had a message of congratulations this week from George; saying that he's keeping a watchful eye on our project. In return, I inquired if George might be able to put me in contact with folk that might help shed light on what was going on at that time (transistor-wise) in the rest of "Hamdom". That is, I'd like to assemble a folder on the topic of "first transistor QRP QSOs" for Japan, Western and Eastern Europe, Australia, etc.. I'll keep you apprised of any news.

That's all from here, Jack. Once again, I'd like to express my thanks to you for including me in your project. It's already been great fun and a real pleasure to meet some wonderful people.

Kind regards,
Mike, AA1TJ

Technical Manual 11-455 -- Radio Fundamentals -- July 17, 1941

This is an illuminating little book.  It was published by the U.S. War Department on July 17, 1941, less than five months before Pearl Harbor.   Far from being dated, this book contains a lot of  great explanations of -- as the title indicates -- the fundamentals of radio.   I turned to it this morning for a little refresher on the physics of regenerative feedback.  

You can get your own paper copy here:  

https://www.amazon.com/Technical-Manual-Radio-Fundamentals-11-455/dp/B000HI6306

Or here: 

https://www.ebay.com/itm/War-Department-TM-11-455-Radio-Fundamentals-WWII-1941-/141763081079

Or you can read a slightly more recent edition (1944!) online (free) here: 

https://archive.org/details/Tm11-455/mode/2up

Please let me know if you find this book useful.