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Monday, May 13, 2024
Ragnar LA1UH's Wonderful Museums in Norway
Sunday, April 28, 2024
A Soviet Tube in Cuba: The "Little Spider"
I hope readers have picked up on the discussion of the Islander DSB rig out of Cuba. We had a bit of a breakthrough on this recently. I've been writing about it on the blog:
https://soldersmoke.blogspot.com/2024/04/re-building-islander-dsbcw-rig-in-cuba.html
Thursday, November 30, 2023
AA9IL's Sputnik Tube, Altoids Tin Transmitter
Saturday, November 25, 2023
Some Short-Wave Listener QSL Cards
Sunday, April 9, 2023
Arnie Coro CO2KK (SK) Provides More Info on the Islander DSB rig
Peter Parker VK3YE found this message from Arnie CO2KK in the Wayback Machine. We continue to look for more information on the Jaguey solid state DSB rig.
Arnie wrote:
Several years ago an amateur in central Cuba was approached by some of his young friends to help them build their first rig. CO7PR, Pedro, a telecommunications technician for the phone company, had a vast experience both with vacuum tubes and solid state circuits, plus that special gift of designing and building with whatever is available. After a few days, Pedro came out with the "Islander" prototype, a low parts count, easy to build single band transceiver!
Here is the circuit description of that little radio that has provided many cuban young and old, newcomers to our hobby, with their first rig... and the challenge to improve it.
RECEIVER:
It is a direct conversion, YES, a DC receiver made with vacuum tubes. The very thought of having those tube filaments fed from the AC power supply and at the same time having 80 or 90 dB of amplification made me shudder when I first talked to Pedro on the very popular here 40 meter band! You are LOCO Pedro, I told my good friend... CRAZY, those poor kids are going to hear 50 percent 120 hZ hum when they tune across the 7 megahertz band.
Yes Arnie, you are right, it has a little background hum, but by using a small loudspeaker and small coupling capacitors... it's tolerable! The receiver shares, in its original version, the same antenna input as the transmitter output stage, a PI network, but we soon learned to add a separate LC tuned circuit first and latter a bandpass double tuned input filter...PLUS a signal attenuator... a very primitive but effective attenuator... just a 10 k potentiometer!
For an RF amplifier stage the Islander uses a russian pentode, which is the equivalent of the popular TV IF amplifiers of the 50's... looks like a 6CB6, for those of you that fixed TV sets 40 years ago or so.
The 6 "little spider" five, as everyone knows that tube here,has a lot of gain, and it can be kept rather stable by a judicious choice of screen and cathode resistor values.. Noisy pentagrid converter follows!
The 6A2P... a russian 6BE6, was the first tube type used in the Islanders, later some people tried the ECH81 triode-hexode and found it works better.
The circuit of the 6A2P-6BE6 is quite straighforward... a... you guessed right... PRODUCT DETECTOR... fed from the vacuum tube VFO... and providing its audio output to the two stage audio amplifier.
Audio amplifier is made with a triode-pentode tube of which plenty are locally available from defunct TV's... the ECL82 and the 6F4P and 6F5P of east european and russian manufacture respectively provide a lot of gain.
So... that's your receiver.. quite straightforward, works on 160, 80 and 40 meters by just changing the input filter and the VFO injection, it does NOT provide very good selectivity at all, but during the daytime, when the 40 meter band is used for local and regional contacts, it puts those new hams ON THE AIR!
VFO... the big problem amigos!
CO7PR worked very hard to try to make a stable vacuum tube VFO... and he almost made it..
YES, ISLANDERS drift, some not too much, others are not so good, depending on who built the rig, and how close they followed Pedro's advice at first, and Arnie's CO2KK later (as yours truly became quite involved in the project, as soon as I found that it was THE way of getting all those guys ON THE AIR!)
VFO is made with ONE of the 6 "little spider" 5 pentodes... By the way, I am sure you will like to know why the tube is locally known like that... the ZHE letter of the Cyrillic alphabet is something difficult to pronounce to a cuban - or any other non slavic for the matter - and it resembles like a little spider on the tube's carton and... that's why it is not a 6 "ZHE" 5 but a 6 "little spider" five!!!
The VFO cleverly works at one half the operating frequency... and then it DOUBLES frequency at the plate circuit... output is via a link to the pentagrid or hexode mixer depending on which type you use.
BUT... the VFO also has a second output to the transmitting chain.. Well that's the receiver... OH YES... the VFO is fed from a VR tube, a gaseous discharge voltage regulator similar to a VR-150 or VR-105... CO7PR advises to use the VR105, but when building the Islander, special in the countryside, that's a very hard part to find, as old TV sets don't use VR tubes! So people use whichever VR they can find. ZENERS? They are only available locally for 6 to 24 volts, so they can't be used with this rig.
ISLANDER DSB AND CW transmitter circuit:
From the VFO plate circuit, you pick up 7 mHz energy (usually you must wait at least half an hour for that said 7 mHz energy to be stable enough in frequency) and feed two diodes (ex-video detectors from russian TV type D20) acting as what I like to call BALANCED AND UNBALANCED modulator!
When used for DSB, it is certainly a DSB generator... but when you want to work CW, it must be UNBALANCED.something easy to achieve with just a resistor from the +12 volts line and a switch!
The balanced modulator receives its audio from a carbon microphone capsule salvaged from an old telephone, and conveniently connected to same +12 volts with some additional filtering via biggest possible electrolytic + small ceramic dogbone from TV set IF amplifier as RF bypass... no dogbone capacitor there... strange howls on Islander audio as RF leaks into balanced modulator you know.
So dogbone ceramic capacitor is a must! No, disk ceramics are not locally available, so people must use the next best choice... dogbone ceramics in the 100 pf to 5000 pf range, usually rated at 300 volts or so... (that 300 volt rating we learned the hard way, but more about that later.)
The original version of CO7PR's Islander ran with the carbon microphone, no MIC LEVEL control option, as he really wanted to keep things simple... later versions have audio preamps of various designs, and some even have a sort of primitive compressor.. From the balanced modulator the DSB (plus a little carrier leak that is always there) drives the rig's one or two transistor low level RF amplifier, which is made using whatever NPN silicon transistor is available, usually KT315's salvaged from TV's too. the KT315 is sort of a russian version of the 2N2222, so you understand why we use it here!
RF voltage reaches then the grid of an ex-video output amplifier vacuum tube, and there you are... about 2 to 5 watts of either DSB or CW on 40 meters and a new cuban amateur ON THE AIR!
Before I forget... keying... a little chirpy always because of so many interactions between simple circuits, sometimes not too well shielded, first time builder etc.
BUT... ISLANDER is ON THE AIR providing that young kid from the local junior high school or that doctor that always wanted to be a ham, or maybe the fresh out of school electronic technician, with the fascination of their first ever rig. YES, they drift, and some drift badly, when the frequency determining capacitors in the VFO are not too good... (most of the time), as I said they are a little chirpy. and the receiver's selectivity makes working 40 meters at night almost impossible (although some wizards do make nightime contacts at the low end of 7 mHz) BUT. YES, they are ON THE AIR.
Today there are a few Islanders still on the air, and some are even still built brand new (with many of CO7PR's and CO2KK's mods), but the trend is for all solid state rigs centered around CO5GV's and CO2JA's prototype the "JAGUEY," a design that draws a lot from Wes Hayward's Solid State Design for the Radio Amateur, and as of late, with lots of ideas coming from SPRAT, the G-QRP club magazine and QRPp from NORCAL, the Norther California QRP club!!!
In a future posting I will describe the "Jaguey," too.
-------------
More info on the Cuban DSB and AM rigs can be found here:
https://soldersmoke.blogspot.com/2023/04/more-info-on-cuban-jaguey-solid-state.html
https://soldersmoke.blogspot.com/2023/03/homebrew-am-from-cuba.html
https://soldersmoke.blogspot.com/2023/03/more-cuban-homebrew-from-80s-and-90s.html
https://soldersmoke.blogspot.com/2023/03/schematics-for-cuban-islander-double.html
https://soldersmoke.blogspot.com/2023/03/the-islander-homebrew-dsb-rig-from-cuba.html
https://soldersmoke.blogspot.com/2023/03/needed-more-info-on-cuban-islander-or.html
Monday, August 8, 2022
Polyakov (RA3AAE) Direct Conversion Receiver: 40 meter DC RX with VFO at 3.5 - 3.6 MHz (with video)
I've been reading about Polyakov (or "sub-harmonic") Detectors for a long time:
https://soldersmoke.blogspot.com/search/label/Polyakov--Vladimir
But until now, I never built one. Recently, Dean KK4DAS and the Vienna Wireless Makers group have been building a Direct Conversion receiver. Their receiver uses an Si5351 as the VFO, but of course Dean and I have decided to try to do things the hard way by building non-digital VFOs. At first we just came to the conclusion that my earlier Ceramic Resonator VFO wasn't much good (it drifted too much). This led us into standard Colpitts and Armstrong VFOs, and the fascinating world of temperature compensation. Then I remembered the Polyakov circuit -- this would allow us to use a 3.5 MHz VFO on the 7 MHz band. Lower frequency VFOs are easier to stabilize, so I started building my first Polyakov receiver. You can see the results (on 40 meters) in the video above.
I started working with a circuit from SPRAT 110 (Spring 2002). Rudi Burse DK2RS built a Polyakov receiver for 80 and 40 that he called the Lauser Plus. (Lauser means "young rascal" or "imp" in German.) For the AF amplifier, I just attached one of those cheap LM386 boards that you can get on the internet. With it, I sometimes use some old Iphone headphones, or an amplified computer speaker.
Sunday, October 31, 2021
Buy a Real Sputnik Satellite! Let's Put Sputnik Back in Orbit!
Here's the description:
---------------
Laboratory Test Model of "Sputnik 1 EMC/EMI", 1957
1:1 scale test model of the satellite "Sputnik-1", serial no. "0K6-1/004/1957", with built-in transmitter (including modern 12-volt power supply), polished stainless-steel sphere, consisting of two threaded hemispheres of approx. 23 in. diameter with two pairs of antennae of 95 in. and 105 in. at an angle of 35 degrees to the axis, on stand with O-ring, stand approx. 59 in. high, stand and model together approx. 79 in. high, accompanied by a Tesla Maj 620A radio receiver, manufactured in Prague c. 1956, restored working condition, including replacement of the silver-zinc battery with a modern alternative and a new metal casing for the electronic transmitter. Note: Built at the Experimental Design Bureau-1 (OK?-1/OKB-1) factory, also known as S.P. Korolev Rocket and Space Corporation Energia, Koroljow, Soviet Union, in 1957, shortly before the launch of Sputnik-1. - An impressive artefact from the dawn of the space age, of which few models are known. - Provenance: From the collection of Dr. Frank Malina, USA/CSSR.
Start Price: EUR 85.000
Here's my suggestion: Musk or Bezos or Branson should buy this thing, fix it up a bit, and put it back in orbit. So we can listen to it again. I know a version of this was done back in 1997. But I think we should do it again, this time with the actual test model.
Here are the earlier SolderSmoke blog posts about Sputnik and Sputnik-related projects:
https://soldersmoke.blogspot.com/search?q=Sputnik
Steve Silverman sent the auction posting to me. Thanks Steve.
It just so happens that earlier in the week I was out at the Air and Space Museum facility near Dulles Airport, where I saw this flight backup of the Vanguard satellite:
Tuesday, February 9, 2021
Meet Your New Soviet Neighbor -- With Hallicrafters
Saturday, September 5, 2020
Taming Glitches in a Soyuz Space Clock (Plus -- Inside a Logic Chip and How Crystals Work)
Thanks to Bob KD4EBM for sending this.
There is so much good info in this video: They crack open a logic chip and look at the internal construction (it is entirely understandable by mortal minds). They use cool test gear to troubleshoot the clock from a Soyuz spacecraft. They explain very clearly the series and parallel resonances of quartz crystals, then display these resonances on a very nice spectrum analyzer.
The creator of the video is CuriousMarc. He has many other interesting projects:
https://www.youtube.com/c/CuriousMarc/featured
https://www.curiousmarc.com/
Friday, June 5, 2020
Sunday, August 13, 2017
Audio Clips from N2CQR/HI8 Contacts with MIR Space Station (now in mp3)
http://www.gadgeteer.us/CLIPS.HTM
Sunday, April 16, 2017
Micro-Shocks (and QRP Power?) from Nearby High Voltage Lines (video)
I spotted this on Hack-A-Day. It caught my attention because many time, while riding my bike along the Washington and Old Dominion bike path, I have felt electrical shocks from the handlebars.
Now, before you all conclude that OM Bill is losing it and start suggesting that I wear an aluminum foil hat, realize that the bike path is directly under some seriously high voltage power lines. And that esteemed UK newspaper "The Daily Mail" confirms that these shocks are, as the kids say, a thing.
http://www.dailymail.co.uk/news/article-2655190/Cyclist-told-grab-metal-bike-time-rides-overhead-power-line-gives-ELECTRIC-SHOCK.html
So think these Russian dudes are onto something. How long will it be before the QRP community starts exploiting this power source? (Please be careful about where you put the antenna!)
Tuesday, March 21, 2017
FB IBEW HB DC CW de UAE: A65DC's International Homebrew Rig
Good evening!
Wednesday, August 31, 2016
A Signal for SETI? HD 164595
Saturday, February 27, 2016
Sputnik Replica Transmitter, an "Error" in the Sputnik Schematic, and Why 20.005 MHz?
Sunday, October 11, 2015
The Amazing History of the Gibson Girl Rescue Radio
Thursday, April 16, 2015
One more on Gagarin
Bill, Pete,
In keeping with historical events, I have enclosed a few snap-shots from the 1961 Pittsburgh Press dated Wednesday, April 12, 1961.
Yes, a few of us recall that very day. I had filed this newspaper in my Scrap Book back then. It was a bitter sweet thing, to read for most, as we hoped the U.S. to be first but none-the-less, we smiled anyway because, it proved a person could go into space and return. (Flight Breaks Barrier to Space Travel). I was very enthusiastic about Rockets, Travel and current events. I built my own capsule in the rafters of my parents home and spent all day up there in the tiny confines as I launched my own secret adventures into Outer-Space.
Hope you enjoy the photos. I can provide a better set of copies if you are interested.
73's
Harv - WA3EIB
Idaho Falls, ID
Harv: I converted a small closet into what I saw as an excellent simulator of the Apollo 11 Command Module. Bill
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
Cosmonautics Day Follow-up
Very cool Mark (and I think the bird pictures are just as cool!)
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