RADIO HABANA CUBA
DXERS UNLIMITED
MID-WEEK EDITION
TUESDAY, AUGUAT 21, 2001
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos radio-aficionados!!!! Welcome to the mid week edition of your favorite listener-oriented radio hobby show. I am Arnie Coro, radio amateur CO2KK, your friend here in Havana and host of this twice-weekly program, entirely, absolutely devoted to our wonderful and fascinating hobby...RADIO... And NOW, here is the menu for today, amigos...
Item one: Extremely low parts count amateur radio transmitter, even simpler than the ONE PLUS ONE rig we described here recently... this one is still simpler and I already have made several CW radiotelegraphy contacst with it...
Item two: The ONE PLUS ONE rig continues to bring in feedback from Dxers Unlimited's fans... Ernie Marquez in Florida sent me an enthusiastic e-mail about his success with the simple ham radio rig, and Ernie is going to add a keyer to it...
Item three: Antenna topics section will deal today with the half square for the two meter band, an antenna that you can homebrew using readily available materials...
Our popular "you have questions and Arnie answers them" section will deal today with the design of new buildings and how architects and engineers are forgetting that people using those buildings do want to listen to the radio!!!
And as always at the end of the show, Arnie Coro's Dxers Unlimited's HF propagation update and forecast will provide you with short wave radio's must up to date information in an easy to understand way, so that you can enjoy radio a lot more...
Margarita Delgado is my sound engineer and producer, we are working here today at RHC studio number 7... stay tuned for more radio hobby related information after this short musical interval...
The ONE PLUS ONE, the amateur radio transmitter built using just one integrated circuit and one NPN power output transistor has proven to be quite a success among Dxers Unlimited's fans that are also amateur radio operators... The straightforward design can be implemented using the very easy to assemble dead bug type of construction, that is by just gluing the integrated circuit and transistor upside down, with the legs up, to a piece of copper foil printed circuit board. The pc board acts as a ground plane to which you solder the parts that connect to ground, and wiring is extremely simple, not requiring artwork or the messy chemicals needed for the production of homebrew printed circuit boards.
My prototype ONE PLUS ONE serial 003, is now operating on the 30 meter ham band, thanks to a friend that gave me a nice quart crystal that resonates very near to the lower edge of 30 meters... The 30 meter version of the ONE PLUS ONE, keys very well, and is providing about 3 watts output into my wideband antenna... So far I have made just a few contacts with stations in the United States and Canada, no Europeans or Asian stations yet, but the reports received tell me that as soon as HF propagation conditions get better, the little rig is going to bring in some nice transatlantic DX too.
NOW, let me tell you what happened last Sunday... a friend visited me, and saw the ONE PLUS ONE, I had to give him a 7400 IC removed from an old computer card, and a few more parts to complete the kit of components for his ONE PLUS ONE. He went home and Monday evening, he was on the phone asking me to tune around 7050 kiloHertz because his ONE PLUS ONE was already on the air... We had a nice two-way CW QSO using ONE PLUS ONES at both ends, and then he asked if I could design a circuit that could beat the ONE PLUS ONE, that is, using fewer electronic components.
Well Orlando, I told him, I think it can be done... and late Monday evening I had the one transistor, 2 resistors, 1 fixed and 1 variable capacitor rig on the air on the 40 meter band...
YES amigos, you heard it right, just one transistor, two carbon resistors, one disk ceramic capacitor, a variable capacitor from an old radio, plus a quart crystal and a homebrew coil.... The rig was wired dead bug style on a small piece of PC board,and powered from my workbench power supply... I used a transistor that was removed, that is recycled, from a dead computer disk drive, and the coil form was a discarded 35 mm film container... plastic of course.... I wound 20 turns of no.20 enamelled wire, with a tap at 7 turns for the transistor and then wound a 4 turn link...
When connected to the CO2KK broadband antenna, via the antenna tuner, the little rig moved the power meter needle to around 1.5 watts, and sure enough, a Cuban station heard my CQ and came back to me during this first test... So, now you know that with still fewer parts one can make a useable ham radio transmitter.... It won't be a record breaker, and you won't win a DX contest with it, but, its so easy to build and to operate that I am sure many of you will like to have the circuit diagram and building instructions for the ONE ONLY rig, a one power output transistor rig that so far I have tested on 160, 80, 40 and 30 meters... and of course I will send you the complete set of data for winding your coils for those 4 bands...
Send your request for the ONE ONLY single transistor amateur radio transmitter to arnie@radiohc.org and don't forget to include a signal report and comments about the show, as well as any suggestions or new ideas you may want to include in our program...
If not yet in cyberspace,send your request via AIRMAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba....
The name of the station is Radio Havana Cuba, the name of the show is Dxers Unlimited, and yes, you are invited to stay with us for Dxers Unlimited's antenna topics section.... The now popular among Dxers HALF SQUARE vertical wire antenna can be easily adapted for the 2 meter amateur band. The 2 meter HALF SQUARE is very easy to homebrew, and among its significant advantages is the fact that if you go exactly by the measurements provided by us, you won't need a VHF standing wave ratio meter to adjust it... Of the more than twenty HALF SQUARE two meter band antennas built here by radio amateurs, none has required absolutely any adjustment... when we have checked them later using professional measuring equipment, they all came up with a very low standing wave ratio...
The two meter band HALF SQUARE is fed using 50 ohm coaxial cable and an easily built coaxial choke balun to decouple the antenna from the coaxial downlead... The two vertical elements of the antenna are 56 centimeters long each, and the horizontal wire that connects them is 94 centimeters long... The center of the coaxial cable connects to the base of one of the two vertical elements, and the braid or shield of the coaxial cable connects to the horizontal wire that goes to the base of the other vertical antenna. I have used plywood as the support for the antenna, but it is better to use PVC pipe, because it will last longer.
The plywood support version of the HALF SQUARE for two meters was the first prototype and we had to use it during one of last year's hurricane, when our Radio Club was asked to provide communications at a location where the sea wall usually is jumped by huge waves and that part of the city floods in a very short period of time...
As always, with all Dxers Unlimited's radio hobby projects, complete, detailed building instructions are freely available, and you can be sure that each and every circuit and antenna mentioned here was fully tested before it was made available to our worldwide audience... As a very good friend and long time listener of our show likes to say, you can't go wrong with Arnie's radio hobby projects and if you have any doubts, just sending an e-mail to arnie@radiohc.org or an AIRMAIL postcard to Arnie Coro, Radio Havana Cuba, Havana, Cuba, will bring back a very fast reply clearing up your possible doubts...
The HALF SQUARE two meter band antenna, a very easy to homebrew 5 dB gain antenna for your handie-talkie is made using no 10 or no 8 copper wire, a length of PVC pipe and a length of 50 ohm coaxial cable with its connector soldered at one end... Want to learn more about one of the lowest cost and easier to build 2 meter band vertical antennas... just send an e-mail to arnie@radiohc.org or an AIRMAIL postcard to Arnie Coro, Radio Havana Cuba, Havana, Cuba...
Yes amigos! Architects and engineers should learn more about radio and TV reception problems that people are having in recently built buildings. According to our good friend in Atlanta Maryanne Kehoe, the newer office buildings do provide a lot of facilities but radio reception inside them is almost impossible, and the same holds for TV sets. The problem with AM reception can be traced to the use of so called energy-saving fluorescent lamps, each of them a wideband pulse transmitter that wipes out reception over a wide band of frequencies... Short wave receivers, even when located close to the big picture windows are also victims of the many electronic gadgets that form part of the newer buildings, like thermostats, elevator controls, alarm systems, fire warning systems etc..
And don't think that office buildings are the only ones where radio reception is becoming next to impossible -- modern hotels and apartment buildings also have similar problems, as more and more people own home computer systems that use switched mode power supplies, capable of distorting the power line wave beyond recognition, not to mention the terrible spikes generated by the high current devices controlled using state of the art semiconductors....
Not too long ago, a well known Cuban architect was telling me about the so called "intelligent buildings" and I asked him a question that left him scratching his head. My question was if among the virtues of the "intelligent building" was wiping out their users' possibilities of receiving radio and TV signals....
And now amigos, as always, at the end of the show, here is Arnie Coro's Dxers Unlimited's propagation update and forecast... Solar flux still moving slowly, solar activity was low during the weekend and will stay at that level during the next several days... The slow transition to the equinoctial season is now in progress, and you will soon notice that the higher frequency bands will start to behave a lot better as we approach the autumn equinox...
Best bands for daytime listening continue to be 19, 16 and 13 meters, with 13 meters showing a marked improvement during the past several days... For radio amateurs, 20, 17 and 15 meters are the best bands to operate, with 20 meters providing nice DX even late in the evening... Solar flux was very near 160 units on Tuesday, and the A index was 8....
See you at the weekend edition of the show and look for CO2KK with the ONE PLUS ONE CW rig very near to 7040 kiloHertz during my local evening hours, from 0200 to 0400 UTC. Maybe we will soon have a nice two way QSO on 40 meters with the little homebrew wonder rig!
Arnie Coro CO2KK
Havana, Cuba
August 21, 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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