Needed: More Info on the Cuban Islander or Jaguey DSB Transceivers

CO6CBF: "I began operating on the HF bands using homebrewed radios. Mainly on CW running just 10 Watts. My very first phone transmitter was a controlled carrier AM modulator for the 160m band using tubes and components salvaged from an old TV set."

My good friend Dean KK4DAS has built a DSB rig for 10 meters and is working a lot of DX with it.  Peter Marks in Australia has also jumped into the DSB game.  A few of the students we are working with at the local high school may get their General Class licenses and convert their Direct Conversion receivers to Double Sideband transceivers. 

All of this has caused me to reminisce about the famous Cuban Double Sideband rigs. Homebrew Hero Arnie Coro CO2KK used to talk about these rigs on his "DXers Unlimited" program on Radio Havana Cuba.   But Arnie recently passed away, and with him I think a lot of the background info on the Cuban DSB rigs has also disappeared. I find very little about these rigs on the internet -- I have not been able find a single picture.  The Radio Havana Cuba archive of Arnie's shows has disappeared.  

Back in February I talked to Yulian CO6YI on 20 meters about the Cuban DSB rigs.  He said he had a lot of background info on them, and said he would try to send it to me.  I hope he is able to do this. 

The results of my initial Googling appear below.  There has to be more out there. I'm thinking that there must be a lot of background info on the Islander and Jaguey rigs sitting on the hard drives of radio amateurs.   It is time to give this info wider circulation.  Please send me any info you have on these rigs.  Of particular interest would be schematic diagrams and photos of the rigs.  

 

https://www.paara.org/newsletter/2000/graph200007.pdf

The Super Islander Mark VI: https://docplayer.net/24137256-Radio-havana-cuba-dxers-unlimited-s-weekend-edition-for-sunday-sunday-9-august-2015-by-arnie-coro-radio-amateur-co2kk.html

Date: Mon, 22 Mar 2004 17:48:59 -0500
From: "Prof. Arnaldo Coro Antich" 

Subject: Re: GB> 6EH7 vs. 6EJ7 as RF Amplifier

 Dear amigo Chris:
You are absolutely right !
EF184 is the best pentode for RF amplifier duty...
But, let me ask you something... have you thought
about the ECC88 and the even better ECC189 dual
triodes that were designed for TV tuner work, and
that incidentally were also about the last vacuum tubes
ever designed from ""scratch"" until Phillips and other
European manufacturers stopped from making
receiving type vacuum tubes.
The ECC189 is simply wonderful for a front end !!!
I am sure that you are aware of our limitations here at
my QTH regarding the possibility of obtaining solid
state modern devices... so we still make ""new"" ham radio rigs using mostly
vacuum tubes...
We even still make a version of "" The Islander"" a DSB transceiver with
direct conversion vacuum tube receiver...
Tube lineup is
EF184 RF amp
ECH81 product detector
ECH81 triode section not used
ECL82 triode audio preamp
ECL82 pentode audio output
6AH6  VFO ( Russian equivalent 6*5P )
Audio filter provided by good working brain of
operator !!!
Keep up the good work amigo !!!
73 and DX
YOur friend in Havana
Arnie Coro

CO2KK

http://ibiblio.org/modena/GLOWBUGSpiobaire/glowbugs.piobaire.weekly.html

Today’s first question came from a long time listener in India. Rajiv 
tells me that at this moment he is not able to pick up our station on 
the shortwave bands, and he rightly assumes that this is because of the 
very low solar activity… but Rajiv who lives in the garden city of 
India, Bangalore, the home of the nation’s electronic and other high 
tech industries, is able to read the scripts of the program that are 
made available to several short wave listeners clubs e-mail distribution 
lists. Rajiv tells me that he wants to obtain the electronic files of 
the Super Islander amateur radio transceiver to compare the circuit 
diagrams and design philosophy with a similar project that is becoming 
very popular among Indian radio amateurs.
Ok amigo Rajiv… I have already sent you all the files including some 
nice digital photos of the first prototype of the Super Islander, that 
as you will see, has two final amplifier options , one built using NPN 
RF power transistors, and the other one using two vacuum tubes that are 
very easy to find here in Cuba from recycled TV sets. The Super Islander 
is a single band transceiver that can be built for the 160, 80 or 40 
meter bands. Here in Cuba amigo Rajiv, the most popular amateur band 
nowadays is two meters, using the FM narrowband mode, and the second 
most popular band among Cuban radio amateurs is 40 meters, that’s why 
most of the Super Islanders are built for operating between 7.000 and 
7.150 kiloHertz.  The double sideband signal generated by the Super 
Islander simple circuit is very stable, and very few if any radio 
amateurs that contact stations using the Super Islander are able to 
detect that it is a double side band and not a single side band signal 
what they are hearing. One of the most outstanding features of the Super 
Islander single band amateur radio transceiver is that it is modular, so 
those who want to build it, are able to build and test each module as a 
single project, and after all the modules are fully tested, then they 
are easily wired together . The parts count, that is the number of 
components required to build a Super Islander was kept intentionally as 
low as possible, both to simplify its construction and to increase the 
reliability. I hope that amigo Rajiv in Bangolore , India will be able 
to make good use of the Super Islander’s files, and maybe even go ahead 
and build one , as the parts required are almost universally available, 
because that was one of the design requirements that I set when starting 
the  Super Islander project more than fifteen years ago….You can learn 
more about this simple amateur band transceiver by sending a request for 
the Super Islander files to arnie@xxxxxx … I will send it as a dot zip 
file and you will be able to see circuit diagrams, photos and full 
descriptions of the different modules of this nice little rig, that has 
proven itself under the most difficult circumstances, like handling 
emergency communications links during tropical storms.

http://www.hard-core-dx.com/hard-core-dx/2007/msg02587.html

https://studylibfr.com/doc/10070052/nmrevue-012008

Beginners generally build one of two radios; the vacuum tube Islander or the solid state Jaguey. The Islander is a DSB/CW Cuban design using a very clever low parts count circuit and a direct conversion receiver. The Jaguey, named for the Jaguey Grande Radio Club in Matanzas province, is a generic design, with a DC receiver, DSB and CW, using solid-state components. Many of its ideas are from Wes Hayward's W7ZOI's Solid State Design for the Radio Amateur. The lack of mechanical filters or quartz crystals to homebrew SSB filters made Cuban designers CO5GV, CO2JA and CO2KK choose a DSB and CW rig. Fitted with good quality capacitors for the VFO, it works quite well from a 12-volt car battery in hurricane emergencies.
https://web.archive.org/web/20140917014137/http://www.worldradiomagazine.com/old_wro/articles/features/cuba.html

Re-building the Islander DSB/CW Tube Rig in Cuba

The VFO Board

The "motherboard" for an Islander

Islander boards recently obtained in Cuba by CO7WT

Pavel CO7WT is making great progress in re-building an Islander DSB rig, the same kind of rig that got him started in ham radio, and that was so popular in Cuba years ago.  Here are some background blog posts on this rig:  https://soldersmoke.blogspot.com/search?q=Islander  In essence, the Islander was the earlier tube DSB/CW rig; the Jaguey was a later, solid-state DSB/CW rig. 

When they get this Islander going, hams outside Cuba should definitely try to work this re-creation of an important rig. 

Thanks Pavel for all the information.  I will share with the group info that Pavel sent about temperature stabilization techniques used on this rig.  

Pavel CO7WT writes: 

Great news, today I received the package from my colleague in zone 6.

Two original islander motherboards and one from the vfo!

I'm doing a search among old technical friends in the city and in the country to see if I can put together at least a transceiver motherboard.

Audio triode-pentode is easy, as is tx pentode and audio double triode.

The difficult ones would be the 6cb6 and 6bz6 of the receiver... At least according to what I have polled among my local friends...

Tomorrow some friends are going to start looking for bases and valves that can be used to build a trx islander.

All out of pure nostalgia. I intend to make it qrp, that is, up to the output pentode, which there is between 3-5W of power, that is enough for me.

I am looking for alternatives for small sources, perhaps I will use switching for the filaments and we will see what I can get for the 180-250v of the plates.

Earlier: 

CO7WT here, built a pair of the Islander back in the time, the most scary part was the power supply.

The 600V is 300ish V from the transformed DOUBLED stright from the transformer and if you look closely on the diagram the doubling capacitor need to be of good quality otherwise it will explode in the spot.

As you can imagine, using scrapped parts means that very often this capacitor explodes, even after a few months of duty, that was a common problem.

We used to use 47uF/800v from Germany that was almost easy to obtain, but exploded like fireworks a given day.

Later I learned that if you put a resistor of about 1k 5W in series and work it for a while like this [no real voltage at the end] it will behave in the future and this trick saved many, a trick that was shared with Coro CO2KK and he found the explanation on the taming/training of the dielectric after storage/inactivity will prevent it from exploding.

I think he made mention this on a DXers Unlimited program...

The Super Islander Mark IV -- A Cuban DSB Transceiver Made From CFL Lightbulb Parts

Trevor Woods also sent us this report from Arnie Coro.  It is not clear to me what difference (if any) there is between the Super Islander Mark IV and the Jaguey Five (described yesterday).  But the bit about using parts from old CFL bulbs is interesting.  This was something championed by Michael Rainey AA1TJ several years ago.  See: https://soldersmoke.blogspot.com/2009/01/soldersmoke-98.html  

and:

https://www.qsotoday.com/transcripts/aa1tj

April 2010:

Today, I will be answering a question sent by listener Bruno from Croatia... Bruno picks up our English language programs via Internet, but he is now also listening on short wave too. He sent a nice e-mail message asking me about the latest version of the Super Islander amateur radio transceiver, because he wants to build one.

Well amigo Bruno, the Super Islander Mark IV is now on the air, and results are very encouraging considering that it is a 40 meters band transceiver built using recycled electronic components.

The Mark IV uses a totally different approach to the receiver design, and it adds two solid state audio filters.

Amazing as this may sound, some of the electronic components used to make the Super Islander Mark IV transceiver came from the circuit boards of broken or damaged Compact Fluorescent Light Bulbs... and that means that there is virtually an endless supply of those parts.

Here is now amigo Bruno, and amigos listening to the program at this moment, a brief description of the Super Islander's Mark IV receiver module.

It starts with a simple resistive signal attenuator that feeds a dual tuned bandpass input filter.

The filter has a limited bandwidth , chosen so as to limit response to out of band signals... The filter is followed by a cascode transistor radio frequency amplifier stage, that feeds a broadband four diodes product detector.

Low level audio from the product detector goes to the audio filtering and amplifying module, made with discrete transistors, of which several of them are also recycled from the Compact Fluorescent Light Bulbs circuit boards...

This version of the Super Islander, the Mark IV , is radically different from any previous ones, as we have now switched over to a totally low cost solid state design , that can be easily reproduced because it uses very common electronic components and straightforward , easy to adjust circuits.

In our upcoming mid week edition I will describe the VFO, or variable frequency oscillator and the transmitter module of this unique low cost amateur radio transceiver, the Super Islander Mark IV... about the lowest possible cost transceiver that will make possible regular two way ham radio contacts on the 40 meters band using either voice or radiotelegraphy modes.

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

The Islander -- A Homebrew DSB Rig from Cuba

 

This article, the pictures, and the comments are all so cool. They really capture the spirit of homebrew. Obviously we still need more information on  the Islander and the Jaguey.  If you have it, please send it to me and I will disseminate it via this blog. 

From: https://www.frcuba.cu/filiales-grupos/villa-clara/contra-el-olvido.html  with translation by Google.  

I've been in touch by e-mail with Jose Campos CO6EC (the guy in the picture above).   He sent me this partial schematic of the Islander (we still need the VFO circuit and the RF amplifier) .  Thanks Jose! 

Published: 06 August 2018

Views: 2274

Comments: 6

Remembering

By José de Jesús Enríquez Campos (CO6EC)

Next 2019 will be the 30th anniversary of the first convention of radio amateurs in the province of Villa Clara, in Campismo de Ganuza, municipality of Corralillo, on the North coast, about 100 kilometers from Santa Clara, the provincial capital.

This convention was held on a national basis and colleagues from all the country's provinces participated at that time. We did not reach a thousand members throughout the national territory and most of the radio amateurs worked in the 40-meter Band in Amplitude Modulation Then the Lateral Side Band (SSB) was the privilege of a few and the 2 meters was something rare, which did not yet exist in our environment.

At that meeting, a project for a Tube Transceiver was presented, quite simple, with just six vacuum tubes and a BF310 transistor. It was possible to work in HF in Double Sideband, achieving a greater efficiency than the transmission in Modulated Amplitude (AM). This project became known as the Islander.

In only two printed plates, one for the VFO and another for the TX and RX part, which by the way were printed for distribution, in a company in Villa Clara, due to their easy construction and acquisition of the components (almost all of them came out of a Krin-218 TV), a large number of such equipment were manufactured by radio amateurs from all over the country. Like everything made at home, it always comes up with a little problem that later is necessary with tinkering, correcting it.

I remember listening to an old radio amateur from Havana (whose callsign I don't remember) in a pleasant QSO with another colleague, who jokingly said, "... some "Bugs" have now appeared in the band, called Islander, which is worse than the invasion of the Vikings…”, which gives an idea of ​​how many were built at that time, when if you wanted to make radio, you had to manufacture it, something unusual in these times.

As soon as we saw the project we decided to build it, because at that time we had an AM “transmitter” with modulation by “Carrier control” with four tubes, a 12AX7 preamplifier; an ECL82, as a modulator, with cathode output to the final tube Screen grid, a 6DQ6 and a 6BH6 as VFO; and to receive, an old Russian receiver from World War II.
 
 We got involved in the construction and improvements of the project and we managed, with some changes, to improve its performance and quality, because among the modifications to the original, we added: 

 -A switch, with which you could change the transmission mode to DSB -CW-AM.
-A "Pi" Filter at the input of the RX, which considerably improved its quality.
-An automatic volume control, because since it did not have AGC (Automatic Gain Control), when someone nearby came on, it would break your speaker.
-A filter for the microphone input, which improved the quality of the modulation.
-A final power stage, with a 6146B, with 750 V on the board, for about 70 W of  output, taking advantage of the 6P15P as Driver.
-The chassis was built from scratch using aluminum trays that were sold at the hardware store for “four pesos” each and that were special for making cabinets for these purposes.

After the construction was completed in one afternoon, with Reinaldo Martínez Domínguez (CO6UK), from Manicaragua, the balanced modulator was adjusted, since the good transmission of this type of equipment depends on the relationship between the amount of RF and audio that are mixed At that stage, it took us a long time to adjust, until Reinaldo with his expert ear told me, “leave it there, don't touch it, it's 99% complete”.

There were many international contacts that I was able to make with this very simple equipment, with very good reports, many of them with Europe, the American continent, that was very normal, since the propagation conditions in those years had nothing to do with the today, you could do half the world in AM, with about 100 W.
 
Many colleagues at that time asked me what equipment I was using.  When I told them it was an Islander, they asked me to send them the plans of the improvements made, they were many modified plans, mimeographed.
 
Perhaps the youngest do not know what that was and the photos taken by colleague Joel (CO6JC) that helped to illustrate the distribution of the components in the chassis, were sent to radio amateurs from the different provinces, in the interest of contributing modestly to migrate from AM to the Double Side Band, today it is a rarity to listen to someone on AM, there are already few who appear in Double Side Band, which shows that we have developed in these almost 30 years, despite the difficulties, which We went from just under a thousand to about 8,000 throughout the country today.

From time to time, a colleague in the 40 meter Band, from another province, has told me that he still keeps the plans and photos that were sent to him at that time, or as "Kike" (CO6GO) that he still has a Islander as a relic.

Ours passed away a long time ago and part of its components went to other projects, thanks to Joel (CO6JC) there is a graphic record of it, and that at that time I had hair, which I have lost in these bustles.
 
With this brief comment, we only want the new generations to know what radio amateurs were like in those days and the older ones to remember it.

Nothing, to remember is to live again.

Here he left you some images.

• (co6ec) Jose de Jesus Enriquez Campos

  Monday, 06 August 2018 19:30

  The first Image was the prototype presented at the Ganuza meeting, the rest of the photos were the ones we built with the improvements, and the photos and plans were sent to many colleagues, the colleagues who went to that meeting will remember, well, they still have to there are many left, because that was almost 30 years ago,
  greetings CO6EC

• (co8zz) Raul Verdecie

  Monday, August 06, 2018 23:12

  Magnificent photographs!!!... They seem to have been taken today with some digital "super camera"!!!
  Really, from what I can see now, the CO6EC Islander was the perfect example... mine (my first radio and built by me) was also made like this, with the plates that the FRC sold and it was good, but very ugly ...HI... The AGC worked wonderfully as it came, I don't know if Jose's improvements were later! With it I made my first hundred or so entities only in 40 meters / CW (between 7,100 and 7,150) when it was CL8ZZ. I gave it away so that someone would have their license and now I regret not having kept it... I would have liked to show it now to those who regret not having a radio!!!

• (co8zz) Raul Verdecie

  Monday, August 06, 2018 23:43

  Ah, I can never forget those headphones!!!... my external hearing aids (read ears) are much smaller today thanks to them, they exerted tons of force on the operators' skulls!!!

• (cm6vml) Vidal

  Tuesday, August 07, 2018 23:40

  Very good article, I hope that one day, with a good teacher, I can build my own team, congratulations Jose, regards Vidal.

• (co7wt) Pavel Milanes (CO7WT)

  Wednesday, August 08, 2018 09:52

  Sure...
  
  My first radio and with which I got my CL7WT license back in the 90's an ISLANDER, like that in capital letters.
  
  I remember that the CL only had a small 40m segment (like now) and that it was full of broadcasts as soon as the afternoon fell, it was an odyssey to speak on the radio... you had to find a "little hole" between the Broadcastings where it wouldn't bother you " a lot" to be able to talk.
  
  I remember that the old CO7OC (he is no longer a radio amateur) and CL7HU (now AC7HU) helped me build it with a board I bought at the radio club. I took almost all the valves from the deceased KRIM 218, then I found a store in Camagüey that sold idle things from the workshops...
  
  Turns out they had such a large inventory of "idle" tubes that they couldn't put it on the counter...they let me through to the warehouse...huge...stack of tubes, if I remember correctly I ended up with Chinese or Japanese tubes that they were more sensitive in the receiver... the driver went from a 6P14P to a more robust 6P9, by the end that was a humble 6P44 it became two 6P7s that were a Russian version of the RCA 607 if I remember correctly... in the end it had like 80W.
  
  It goes without saying that when I said on the radio that there were valves in that place "they flew"....
  
  The VFO was the one from the Jagüey, not the original from the Islander, I never knew about the AGC modifications.
  
  I would like if someone has the plans with the modifications to send them to me, just for nostalgia...
  
  My email pavelmc@gmail.com
  

• (co2jc) Carlos Alberto Santamaría González

  Monday, August 13, 2018 00:21

  Brother, your article is very good, because of the nostalgia and also because it talks about what we radio amateurs like: tinkering. I didn't have an Islander because what I started with in 2000 was a Polosa to which two colleagues helped me adapt it with VFO for 40 and 80 m. But I talked a lot with colleagues who did it with an Islander or a Jagüey and participated in the Rueda del Behique that I started in the 80 m. Others in the Hurricane Wheel that started a little later and were heard well. As you well say, the propagation at that time had nothing to do with what it is now, but it was very good to listen to the colleagues who came out with the equipment they had built. Thank you once again for your article. CO2JC

Schematics for the Cuban Islander Double Sideband Transceiver (Please Send More Info)

 

Jose CO6EC has been digging up 30 year-old Islander schematics for us.  Thanks Jose.  This one shows a VFO for the Islander.   Note that it runs on 80 meters, but they select the second harmonic at 40 meters.  This was a smart move that surely helped with VFO frequency stability. 

Jose sent this printed circuit board pattern for the VFO.  Obviously they were making many of these rigs. 

Here is the power supply.  Jose reports that the transformer came out of a Soviet Krim 218 TV set.  As a kid, I also pulled a transformer out of an old TV -- I did it to build a power supply for a Heath HW-32A. 

Here is another version of the Islander.  Click on the image for  a better view.  Jose reports that this version was circulating during the time Islanders were being built.  He says this diagram many have been done by Arnie Coro CO2KK (SK), and may have been circulated on the internet. 

Here's the first schematic that Jose sent.  Again, click on the image for a better view. 

I will continue to gather information on the Islander and the Jaguey.  If you have any info please send it to me.  

Here are some earlier posts on these rigs: 

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

Thanks to Jose CO6EC!  

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 

One thing I think is especially interesting:  The Cubans were using parts taken out of old Soviet TV sets.  One of the tubes used in the VFO section of the Islander was known among the Cuban hams as "the little spider." 

Arnie Coro CO2KK explains why: 

"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!!!"

Old Tricks, Lore, and Art -- Freezing and Baking our LC VFOs -- An Example from Cuba

Pavel CO7WT explained why Cuban hams used a process of thermal endurance to improved the frequency stability of their homebrew rigs: 

  --------------------

I'm CO7WT from Cuba, I started my endeavor in ham radio with a islander board.

They (FRC, like ARRL but in Cuba) made a print of a PCB to build the Islander, with component numbers and values, making construction fool proof, I think it was on the 90 or end of the 80...

Mine was built with scraps from an old KRIM 218 Russian B&W TV as Coro's explain, later on I get the 6bz6 and 6be6 tubes for the receiver (this worked better than the Russian parts) the VFO was transistorized, made with Russian components. A friend CO7CO Amaury, explain me a trick: thermal endurance:

For a week put a crust of ice on the VFO board by placing it in a frosty fridge during the night. Put them in the sun by day. This indeed improved stability, this was an old trick.

By thermal endurance I mean improving thermal resistance vs tolerance, meaning that tolerance doesn't vary as much with temperature changes.

 It's crazy, but it worked!!

I remember that my vfo was on 7 MHz, with Russian kt315 as normal Russian transistors and capacitors, nothing 1-5%, 20% at most, it ran several khz in 5-10 min, mounted on a Russian "Formica" board (no PCB) and wired underneath.

After that treatment to the complete board with components and everything, including the variable capacitor; I managed to get it to "only" noticeably in the ear after 30-40 minutes.

To me it was magic!!

Basically, what I'm describing is just "thermal annealing", but Cuban-style and with more extreme limits.

In a refrigerator you could easily reach -10 c and in the sun for a day in Cuba 60-80 celsius at least.

In Cuba in the 1990s-2010s many designs of DSB radios proliferated, both direct conversion and super heterodine (using an intermediate frequency)

At first tubes and then transistors, mostly using salvaged parts, so it was common to find 465/500 kHz (if common Russian) 455 khz and 10.7 Mhz with or without "wide" filters since narrow filters for SSBs were not scarce: they were almost impossible to get.

Not only that, crystals, ifs, PCBs, transistors, etc.

Then, around the 2000s, Russian 500 khz USB filters began to appear (from Polosa, Karat, etc. equipment from companies that deregistered and switched to amateur radio) and that contributed to improving... Even though at 7 MHz 500kc if is very close.

I made many modifications with the years mostly from 1998 to 2004 ish... better filters in front of the first RX stage (same IF described between stages) improved selectivity and out of band rejection, remember we had on that days broadcast as low as 7100 khz

Tx part was a pair of russian 6P7 (eq. RCA 807) in paralell, etc.

The Jagüey and others is one of those evolutions...

 This is something I remember...

73 CO7WT

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This is not as crazy as it sounds.  We can find versions of the same technique in the writings of Roy Lewellan W7EL, Doug DeMaw W1FB, and Wes Hayward W7ZOI.  I found this 2007 message from our friend Farhan VU2ESE: 

I think the word 'annealing' is a bit of a misnomer. the idea is to thermally expand and contract the wiring a few times to relieve any mechanical stresses in the coil. after an extreme swing of tempuratures, the winding will be more settled.
this techniques owes itself to w7EL. I first read about it in his article on the 'Optimized transceiver' pulished in 1992 or so.
but all said and done, it is part of the lore. it needs a rigorous proof.
- farhan

https://groups.io/g/BITX20/topic/copper_wire_annealing/4101565?p=,,,20,0,0,0::recentpostdate/sticky,,,20,1,860,4101565,previd%3D1193595376000000000,nextid%3D1194269624000000000&previd=1193595376000000000&nextid=1194269624000000000

And here is another example of coil boiling: 

https://www.qsl.net/kd7rem/vfo.htm

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I can almost hear it,  all the way from across the continent:  Pete N6QW should, please, stop chuckling.  Obviously these stabilization techniques are not necessary with his beloved Si5351.  Some will see all this as evidence of the barbarity and backwardness of LC VFOs.  But I see it as another example of lore, of art in the science of radio. (Even the FCC regs talk about "Advancing the radio art." ) This is sort of like the rules we follow for LC VFO stability:  keep the frequency low, use NP0 or silver mica caps, use air core inductors, keep lead length short, and pay attention to mechanical stability.  Sure, you don't have to do any of this with an Si5351.  Then again, you don't have to do any of this to achieve stability in an Iphone. But there is NO SOUL in an Iphone, nor in an Si5351.  Give me a Harley, a Colpitts, or a Pierce any day.  But as I try to remember, this is a hobby.  Some people like digital VFOs.  "To each, his own." 

Thanks Pavel.