Dxers Unlimited for Sunday 10 June 2018

Radio Havana Cuba

Dxers Unlimited weekend edition for Sunday 10 June 2018 By  Arnie Coro radio amateur CO2KK

Hola amigos radioaficionados all around the world and orbiting planet Earth aboard the International Space Station where the crew members continue to enjoy sending back to Earth slow scan television signals on the 145.800 frequency with excellent results… Yes amigos radio amateurs are in space and having a good time during the short periods when they can take a break from the demanding duties aboard the very complex space ship… I am Arnaldo, Arnie, Coro radio amateur CO2KK , your host here at the weekend edition of Dxers Unlimited, the one and only radio hobby show that receives and answers all your questions related to the wonderful way you and I enjoy our free time… playing with our radios and their many accesories. Now here is item two: The summer sporadic E layer season, of the northern hemisphere is now in progress… I am now insisting on the short term forecast for the 2018 sporadic E season. I did send a quick reply to a listener that wanted to know what was the forecast for this year’s E skip season… Here is what I wrote to amigo Richard , in Florida, USA– quote:

Amigo Richard ;

Here is my forecast… expect above average 6 meters Sporadic E summer season for 2018… There  seems to be an evergrowing criteria among 6 meters band Dxers that sees a clear inverse correlation between periods of very low solar activity and the ocurrence of sporadic E events. Will be looking for you with my 6 meters QRP Five Watts and my simple sloping dipole antenna… Yes I have worked many 6 meters stations using a 55 inches whip antenna  with one ground radial 57 inches horizontal ground radial !!! Now I will compile all the observations about the spring and summer 2018 sporadic E season and we will find out if my forecast was accurate or not…with results available by September of this year of minimum solar activity. During the year 2016  several good transatlantic band openings on six meters band were enjoyed by operators all along the East Coast of Canada and the USA and they were able to make many nice contacts using typical stations running not more than one hundred watts on single side band and a three four or five elements YAGI… Caribbean stations also enjoyed the openings to Europe and to North America too. For TV Dxers in the USA this season brought the possibility of picking up many Mexican , Central American and Cuban analog TV stations that are still on the air using the NTSC-M 525 lines resolution transmission standard now in the process of being phased out in favor of digital TV over the air broadcasts—

Item three: … Your attention please homebrewers that can read circuit diagrams, identify electronic parts and know how to solder… for those of you … It is perfectly possible to build a very simple amateur radio CW radiotelegraphy transmitter with a minimum of parts, and yet achieve reliable results… It does need very careful construction to make the home brew self oscillating Hartley rig stable enough to be able to use it on the amateur bands. Results so far show that on the 160, 80 and 40 meters bands, using just ten, yes, just ten parts, the rig built around a single vacuum tube may be used on the air with excellent results… Now let me tell you that when I sent the original schematic of the Hartley single vacuum tube power oscillator to a friend of mine that is a senior telecommunications enginner at Havana’s famous CUJAE technical university,  he came back immediately to tell me not to dare put that transmitter on the air…. because he said it will drift badly and produce an awful keying CW note… Then, my reply went back with an mp3 file of the sound of the Hartley power oscillator on the air…. a nice clean , stable signal free of frequency drift or keying chirp… Courtesy of my long time  Italian friend Cristiano Greggio who has spent a lot of time experimenting with simple vacuum tubes receiving and transmitting equipment that are producing really amazing results… More about low cost amateur homebrew equipment coming up in a few seconds when the weekend edition of Dxers Unlimited continues after a short break I am Arnie Coro, radio amateur CO2KK in La Habana, Cuba

Yes amigos you are listening to Radio Havana Cuba and here is more about low cost , simple equipment for enjoying the radio hobby without having to apply for bankrupcy…. There is no doubt that professional radio receivers designed and built by the German firm Rohde and Schwartz are among the best in the world.  Then you may want to know that a very simple REGENERODYNE  home built vacuum tube receiver is matching and even exceeding the sensitivity of one of the classic Rhode and Schwartz HF radios…
Amazing as it may sound, it is fully documented with many actual comparative tests using the same antenna switched between the two radios… This information also comes from amigo Christiano Greggio of Italy… he tells us that using an ECH81 or ECH83 triode heptode tube frequency conversion stage, feeding another identical tube used as regenerative detector and first audio amplifier stage, when operating on the 40 meters amateur band, reception is very good, making possible to detect very weak signals that are buried into the front end noise of the professional receiver… My version of that radio built using Russian vacuum tubes is now in the works with the added feature of a front end dual tuned bandpass input filter and a single pentode radio frequency amplifier stage just to compensate for the signal lost in the filter… And my audio module will also contemplate the use of two audio filters… I have now almost all the parts needed for the project,  and ready to start testing each component one by one before the parts entry into the assembly line … something that I always do before starting to place the parts into circuit boards or chassis point to point wiring, in order to avoid the problems associated with using a defective part on a new radio…. Believe me, testing each and every part before assembly is a really sound practice…  Also follow my advice and never start the building process before you have at hand all the parts required for the project…I have two projects left at a standstill years ago when a missing part was never found…

And now talking about simple receivers and transmitters let me add that my favorite band for them to operate is 40 meters, because during the daytime it provides very nice local and semi’local coverage and at night it changes into a wonderful band for making DX contacts…40 meters will continue to be a very reliable band for night time Dxing for the next two years amigos…. that is why installing a nice seven megaHertz antenna is also a worthwhile project, especially if you can add to it wire elements for the 30 and 20 meters bands too….

Now  a short form prediction of the solar flux levels for the near term , it will stand at near rock botttom values not to exceed 75 units for the next week or so…The sun continues to show no sunspots for the past several days and solar cycle 24 continues its slow downward trend amigos ! Send your signal reports and comments to inforhc at enet dot cu or via air mail to Arnie Coro Radio Havana Cuba , Havana Cuba… See you all at the middle of the week edition of Dxers Unlimited just after our half hour news bulletin …


About W2JC

W2JC ... formerly W2BVE (WN2BVE in 1955!)
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