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Showing posts sorted by relevance for query CO2KK. Sort by date Show all posts
Showing posts sorted by relevance for query CO2KK. Sort by date Show all posts

Monday, January 9, 2023

Arnie Coro CO2KK -- Homebrew Hero -- Silent Key

I was sorry to read this morning of the passing of Homebrew Hero Arnie Coro CO2KK.  As we see in one of the obits, Arnie got his start in radio at age 12, with the gift from his father of a chunk of galena, a coil, and some headphones. 

Here are some of the SolderSmoke posts about Arnie:  


He will be missed. 

Thursday, February 18, 2010


I was getting ready to write a quick blog entry on Arnie Coro's latest contribution to ham radio (his idea to revive the old 40 meter novice band) when it occurred to me that Arnie's long track record of providing good ideas, technical advice, and inspiration definitely puts him in the HOMEBREW HERO category. Thanks Arnie!

Below you can find the transcript of Arnie's latest edition of Radio Habana Cuba's "DXers Unlimited." There is a good discussion of current solar conditions (improving!) and of Arnie's 40 meter CW initiative.

Arnie's work at RHC is archived and available on the net. It is a real Caribbean treasure trove for us: http://www.dxers-unlimited.dxer.info/

Here is Arnie's blog: http://dxersunlimited.blogspot.com/

From "DXers Unlimited" 16-17 Feb 2010:
Hi amigos radioaficionados around the world now enjoying the ongoing
upsurge in solar activity that has brought to us DX signals as
strong as we had not heard them since 2005 !!! Yes my friends,
finally, after waiting, and waiting, and waiting, we are seeing a
nice comeback of the sunspots... As a matter of fact, only two days
of 2010 had gone by with a totally blank Sun. The all important R
number from the very much respected Catania, Sicily reference solar
observatory was 39 yesterday... and two other sunspot groups are
just about to turn into view...
As a result of the sustained increase in sunspot count, we are
seeing the 15 meters or 21 megaHertz amateur band opening up every
day... I will tell you more about amateur radio Dxing later , here
at th emid week edition of Dxers Unlimited... The daily solar flux
is very near 90, and forecasters were looking at a lower flux during
the next three days, but this may change dramatically and in just a
few hours, if the new solar sunspots regions that are rotating into
Earth's view show high activity.
Item two: The amateur radio hobby is alive and in good health... ham
operators are enjoying the hobby and finding new ways of
improving their communications skills... Here is a recent example,
by carefully studying the behavior of activity on the 40 meters
band, I was able to find out that the band
segment from 7105 to 7125 kiloHertz was seeing very little use here
in ITU Region II, that is the Americas. So I launched the idea to
start using that segment by low power stations, on several of the
popular ham radio Internet mailing lists. In just a couple days , CW
activity , mostly by low power or qRP stations on that segment
roughly 20 kiloHertz segment has increased dramatically... For many
operators, finding such a nice and clear , interference free
segment, has meant having the opportunity of making many more two
way contacts.... and not only exchanging reports, but also , thanks
to less interference, we have carried out some really nice ragchews,
and just notice that I have just said WE, because I am , of course,
one of the happy radio amateurs operating on CW between 7105 and
7125 kiloHertz.
There are no digital stations using that segment... as they are now
present between 7030 and 7040 kiloHertz, the two frequencies were
QRP , or low power operators, are used to gather, and where for the
past year or so, it has become extremely difficult at times to make
even a single two way CW contact.
I am not saying that QRP operators should abandon the two favorite
watering holes, 7030 and 7040, what I have told the QRP , GLOWBUGS
and Regenerative receivers Internet list members, is that the
segment between 7105 and 7125 is in a much better shape regarding
QRM... yes there is a let less interference from other
communications modes...so chances to make nice contacts increase in
a very significant way.
Si amigos , Yes my friends , Oui mes amis...amateur radio operators
around the world are now enjoying the upsurge in solar activity, and
with it, we all must look around the bands and find ways to make
better use of them... After all, many other users of the radio
spectrum are always monitoring the ham bands, just to have data
available to substantiate their requests for more spectrum space....
In other words, if we, amateur radio operators are able to be more
time on the air, and the bands sound like a beehive of activity,
chances that those spectrum hungry users will just go elsewhere !!!

The complete script of the program , devoted to the promotion and
development of our radio hobby in general and amateur radio in
particular, can be read at:
later this Tuesday, after the program goes on the air

Comments , suggestions and ideas on how to help promote
amateur radio are welcome at my e-mail address
inforhc at enet dot cu

72 and DX
Arnie Coro

Tuesday, June 7, 2011

Searching for the Sputnik Schematic

Mike, AA1TJ, has launched (!) yet another intriguing project. See below. In an effort to come up with the actual Sputnik schematic, I have thrown down the geek gauntlet to our fellow nerds at sci.space.history:

Greetings Space Historians!
We are a group of radio amateurs and we probably rival you in our
technical geeky-ness. We are now involved in an effort to re-create
and put on the airwaves replicas of the 20 MHz transmitters used in
Sputnik 1. (We will use the amateur radio 21 MHz band).
We are trying to find a schematic diagram for the transmitter. Can
you help us? Thanks.


Arnie, CO2KK, told me last night that as a 15 year-old boy he'd made
it into the newspaper by picking up Sputnik's signal on his Hammarland
Super-Pro receiver.

Don Mitchell - a physicist now retired from the Bell Labs - also wrote
last evening to ask if I knew of a schematic diagram for the two
transmitters used on Sputnik-1. Mr. Mitchell maintains an informative
web site on the topic of Sputnik. Here, for example, is the link to
his page on the first of the series of "Travellers" to be lofted into
orbit in late 1957 into 1958.


To the best of my knowledge the schematic for what may be the most
famous QRPp transmitter has never been published. It's a shame,
particularly as it would have been great fun to build an approximate
replica for use on the ham bands

However, I woke up this morning wondering why should we allow the lack
of an original schematic to stop us when there's plenty of descriptive
evidence available? "Spaceflight Magazine," for example, published a
wonderful article on the 50th anniversary of Sputnik. The story was
pieced together from original documents over a period of 20 years. You
may read the article here


"The two D-200 type radio transmitters operated on frequencies of
20.005 and 40.003 megacycles at wavelengths of 15 and 7.5 m. These
transmitters (which obviously used vacuum tubes) each had a power
intake of 1 watt and provided the famous “beep-beep-beep” sound to
Sputnik. The signals on both the frequencies were spurts lasting 0.2
to 0.6 seconds, and carried information on the pressure and
temperature inside the satellite; one set would transmit during the
“pauses” of the other."

"Despite objections from just about everyone, Gringauz insisted that
PS-1 carry a high frequency transmitter (the 20.005 MHz transmitter
operating in the decameter waveband) in addition to the VHF
transmitter (which had been commonly used on Soviet ballistic
missiles). ...In the end, Gringauz won over his opponents, partly
because everyone agreed that a high frequency
transmitter would ensure that the radio transmissions would be heard
around the world. The transmitter hardware was built by one
of Gringauz’ youngest engineers, Vyacheslav Lappo..."

>From other sources we know the transmitter used vacuum tubes rather
than transistors. This site mentions that when the received signal
was quite strong, the presence of a back-wave while the other
transmitter was keyed could be noted.


The RF oscillator, at a minimum, must have been free-running. So,
we're talking a vacuum tube crystal-controlled oscillator and a PA
having an input power of 1 watt. They may have used a PA driver stage,
or perhaps a frequency multiplier stage. If they did use a multiplier
then it must have been allowed to free-run as well. But given the
battery drain considerations, I would have done my best to reduce the
number of vacuum tube heaters, or filaments to a minimum. As such, I
think there's a fairly good chance this was a simple, MOPA design
(oscillator-> PA).

I found what might be a photograph of the transmitter on page 26 of
the December 1957 issue of the Soviet "Radio Magazine." Perhaps our
Russian speaking group members can confirm this and provide us with
other clues appearing in the article text? The magazine can be
downloaded at


Click-on ''Radio'',1957,N12.[djv].zip. The "zipped" December issue
appears in DJVU format. Don't miss the nice Sputnik cover art.

This re-post talks about the center-fed Vee dipole used (the 15m
transmitter used the 5.8meter dipole) among other things.


Getting to get the point, this morning I woke up thinking about how
plentiful vintage Russian military tubes are these days. Remember how
inexpensive US military surplus used to be? That's how it is right now
with Russian components (and the characteristics of some of these
tubes are simply amazing). All I can say is get 'em while they're hot,
as it surely won't last forever.

It also came to me that Expanded Spectrum Systems sells an HC49
crystal cut for 21060kHz for two and a half-bucks each.

Finally, I remarked to myself that propagation-wise, 15m may well be
open for business come the 54th anniversary of the launch of Sputnik-1
next October the 4th.

You've probably guessed by now what I'm going to propose. We have
plenty of time to throw together a simple 15m CW vacuum-tube
transmitter having an input power of 1w or less. We could use any
tubes that we like but I'm going to build mine using 1950's vintage
ex-Soviet devices. I plan to power mine with one or two of those
ubiquitous 12V sealed-lead-acid batteries. I'll VXO my crystal and
I'll let it free-run during transmit; both for historical reasons and
to improve the signal quality.

Perhaps some of the antenna gurus here would lend a hand by modeling
and testing something akin to the original 70 degree Vee dipole? Would
this be a practical antenna?

I propose that beginning on "Sputnik Day" we launch our 1 watt Sputnik
clones on 15m CW. Instead of calling CQ, our call could be along the
lines of "Beep_Beep_Beep_Beep_Beep_Beep de AA1TJ". In other words, six
letter E's followed by our call sign. Given that I can barely organize
the socks in my underwear drawer, perhaps someone skilled at
organizing events would take up the cause?

One more thing. Poking around on Google last night, I was struck by
how many people remarked that the experience of Sputnik had changed
their lives. Some decided to become engineers, scientists or amateur
radio operators. I didn't know it at the time, but Sputnik changed the
way that I was educated. Not only did this little QRPp transmitter
make a tremendous impact on the world, but radio amateurs were front
and center. It seems appropriate that we should commemorate this
extraordinary day in the history of QRPp.


(they were seeing the orbiting booster stage rather than the satellite)

Sputnik Mania...the complete film in two parts (warning...contains
some political "button-pushing")
Greetings Space Historians!
We are a group of radio amateurs and we probably rival you in our
technical geeky-ness. We are now involved in an effort to re-create
and put on the airwaves replicas of the 20 MHz transmitters used in
Sputnik 1. (We will use the amateur radio 21 MHz band).
We are trying to find a schematic diagram for the transmitter. Can
you help us? Thanks.


If I happen to learn more about the original transmitter I'll be sure
and post it on my blog or web site. I found particularly interesting
the fact that WWV interrupted some of their 20MHz transmissions in
order to accommodate Sputnik's signal; a gentlemanly thing to do

As for the possibility of an event along these line, any comments or
discussion is most welcome. I plan to make a start on my little
Sputnik sender upon my return from vacation in July.
Greetings Space Historians!
We are a group of radio amateurs and we probably rival you in our
technical geeky-ness. We are now involved in an effort to re-create
and put on the airwaves replicas of the 20 MHz transmitters used in
Sputnik 1. (We will use the amateur radio 21 MHz band).
We are trying to find a schematic diagram for the transmitter. Can
you help us? Thanks.

Ha...I just received several fairly good-quality color photos of the
original Sputnik transmitters! At first glance it looks as though they
used two subminiature pencil tubes! The quartz crystal looks very
similar to our HC-18/u package. The RF portion is very simple in
appearance. In fact, it reminds me of something you'd find in a 1950's
ARRL Mobile Radio Manual! ;o)

The fellow who sent these apparently has a contact with one of the
original Sputnik (non-electronic) hardware designers; who is said to
be "still very much alive." My contact is going to make an inquiry
with his Russian contact about the transmitter.

Very cool...

Mike, AA1TJ

Wednesday, September 17, 2008

Cool Cuban Hack

Arnie posted this on QRP-L. I thought it was a pretty ingenious way to work around
an unavailable part. FB Arnie!

My TS820 non QRP, but capable of QRP operation transceiver. ... has a similar type of female 9 pin socket to connect or not connect the external VFO. I needed a plug when not using the external VFO, and it was made using a Russian 6H2P dual triode that had a bad filament... I very carefully broke down the glass using nichrome wire at red hot temperature and then a thermal shock. The glass bulb broke nicely in a rounded even circle !!! Then I proceeded to remove the soldered connections to the two triodes... removed them , and soldered the wires required for the jumpers as specified by TS 820 manual... After checking that all was OK, then I poured Araldite epoxy to fill the glass ... It worked very well, and the only cost was the small amount of valuable epoxy ( not easy to find locally, and extremely useful for repair jobs and pasting the islands of the Manhattan style homebrew printed-nonprinted circuits !!! 73 and DX Arnie Coro CO2KK

Tuesday, September 16, 2014

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
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

Monday, May 2, 2016

Hallicrafters S38-E Saved! it is not a "Pig with Lipstick." It Sounds Good! (Video) (And Radio Moscow recordings)

You guys know how it is:  You get tired of struggling with an old piece of gear.  You put it aside, thinking that you might never work on it again.  But it sits there in the corner, sort of looking at you.  A few days or weeks or years pass and you think, hey, I'll take one more quick look at this thing to see if I can get it going.

That's what happened to me this weekend with the Hallicrafters S38-E.  I hooked up the isolation transformer and put a fuse in the primary. I checked the wiring of my rewound antenna coil primary and found that I had connected it wrong.  Duh.   I then found that the antenna tuned circuit tracks fairly well with the tuned circuits in the local oscillator. 

I hooked it up to my 40 meter dipole and fired it up.  As evening rolled around the shortwave bands started to perk up.  The Chinese Broadcast stations were there, as was that fire and brimstone preacher Brother so-and-so.   But then I tuned into Radio Havana Cuba and the guy was talking about homebrew shortwave antennas.  Could it be?  Yes indeed.  It was Arnie Coro CO2KK.  The Radio Gods had spoken!  They clearly had wanted me to get this old rig going.

I still have a few things to do:  I need to fix the front panel light.   I want to put in a three-wire (with ground) AC cord.   Perhaps a real BFO (the original circuit seems to run out of steam with strong SSB signals).  And I need to spruce up the alignment on the 1.7-5 Mc and 13-30 Mc bands.

I think Pete and I may have been too harsh on this old receiver (calling it a pig with lipstick and all that).   It is clearly not a great communications receiver, but it is nice for casual shortwave listening. 

And here is a bonus treat for you guys: Remember Radio Moscow in the bad old days?  Yesterday I found a site with good recordings of some of their 1965 broadcasts.  This is  just what you would have heard coming out of an S38-E in 1965:

Wednesday, August 20, 2008


This image (by Michael Weasner) is very similar to what we see when we look at Jupiter through our six inch reflector telescope. Billy and I were up on the roof last night, looking at Jupiter and the moons. Sky and Telescope magazine publishes a nice chart showing how the moons will be configured each evening. Arnie Coro, CO2KK, in the most recent edition of Radio Havana Cuba's "DXers Unlimited" program mentions how easy it is to receive radio signals from Jupiter. I haven't tried that yet, but as a Knack victim, I feel the urge to do so.

We also watched OUR moon rise over Rome, and saw a satellite pass overhead. Saw some neat double-stars, and I taught Billy about averted vision.
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