Wednesday, January 25, 2017

DXers Unlimited - January 22 edition

Radio Havana Cuba
Dxers Unlimited's weekend edition for Sunday 22 January 2017
By Arnie Coro/CO2KK

Hola amigos radioaficionados all around the world.. I am Arnaldo, Arnie,  Coro your host here at the weekend edition of Dxers Unlimited, the one  and only radio hobby program covering almost all of the 91 different  ways we can enjoy playing with our radios and accessories...

First news item... the Sun making a come back of sorts, after stalling  for about 10 days at the beginning of 2017... Sunspots are back in sight and the daily 10.7 centimeters solar radiation flux has moved up to around 85 units...  Correspondingly the next few days will see better propagation conditions on the short wave bands, especially between 10 a 21 megaHertz...

Item two.... good news coming from the European Broadcasting Union...
They are announcing a New dot radio Internet Domain The EBU is launching a new Top Level Domain (TLD) name -dot .radio - aimed at the radio community including Radio Amateurs. The launch is planned for September 2017 and the EBU says this which will progressively change the way people are reaching internet resources linked to radio.

These categories will be accepted for the use of a dot .radio domain:
• Radio Amateurs
• Radio broadcasting stations
• Unions of Broadcasters
• Internet radios
• Radio professionals (journalists, radio hosts, DJs, …)
• Radio-related companies selling radio goods and services
Item three: More and more radio amateurs around the world are learning standard electronic workshop procedures, like soldering , measuring  circuit parameters, reading circuit diagrams , also learning how to  visually identify electronic components, and all that new knowledge opens the way to start building the new generation of user friendly  radio kits... Yes I am very pleased to say that several of the most recently advertised via Internet amateur radio transceivers kits intended to be assembled at home using simple hand tools and standard measuring equipment like the now classic digital multimeters have proven  to be very reliable after proper assembly.

One recent example is the Bayou Jumper solid state QRP transmitter receiver rig, that was derived from the World War II Paraset rig used by paratroopers launched behind enemy lines and by freedom fighters in countries occupied by the Nazis to communicate vital information.  The twenty first century version uses all solid state components for the regenerative detector receiver and the power transistors transmitters...

Limiting the coverage to a narrow segment of the 40 meters band has proven to be a very wise decision, because it has helped to create more activity on the 40 meters band segment between 7100 and 7125 kHz.. Of course that this little rig is a CW only transmitter...  and it is able to receive also single side band voice signals as well as digital modes. Among the bright ideas brought forward by the radio club that is promoting this kit of parts we must include the use of coils that are part of the printed circuit board supplied with the kit of parts. Coil winding to exact specifications has proven to be a long time  problem for home builders. The Bayou Jumper, spelled B A Y O U  J U M P E R uses a single easy to wind toroid coil for the receiver...

The Bayou Jumper Transceiver was designed by two American radio amateurs Jim Giammanco N5 IB and David Cripe N M Zero S---- Here are now some
Specifications and Design Features of this very interesting amateur radio 40 meters band transmitter and receiver set General
     N5IB: Original prototype development, receiver development, PCB and
panel layouts, part sourcing.
     NMØS: Transmitter design, PCB, panel, parts sourcing, assembly manual.
     RXTX Design: Separate receiver and transmitter, built in RIT..
     T/R Switching: Hand switched with a chicken head knob, just as in the old days.
     Single Bander: 40M as supplied.
     Toroids: Only one toroid to wind in the receiver, and none in the transmitter. Only ONE for the whole rig!
     NO SMT: All parts are through hole, there are NO surface mount
devices in the kit.
     Current Requirements: Receiver 20ma, Transmitter 750ma
Enclosure: Beautiful silk screened panel and commercial wooden box,
for a very retro look. Dim. L x W x H, 7.75" x 5.5" x 3.25"

Here is more about how volunteer groups around the world are promoting the home assembly of ham radio equipment by designing rigs that can be successfully completed thanks to the use of high quality electronic components , extremely well designed and made printed circuit boards as well as excellent step by step instruction manuals.

The Bayou Jumper solves many of the problems found in previous attempts of making kits by addressing the most frequent failures of those projects, like for example the need to wind several toroidal ring inductances using very fine wires, a task that is quite a challenge for the older radio amateurs and also to younger less experienced home builders.

Now I am going to share with you the specifications of the performance achieved by the Bayou Jumper kit. Amazing as some them may seem to be, they were all fully verified with advanced electronic test instruments.
     Tuning and Regeneration: Grounded front panel, and insulated shafts
on the controls, so hand effect detuning is minimized.
     Sensitivity: -120 dB (approx S1). Well below the typical rural band
noise level of approx. -100dB (approx. S4).
     Tuning Range: Tuning range approximately 120 to 150 kHz.
     One Knob tuning: No bandset/band spread needed.
     Varactor Tuning: Varactor tuning employing readily available
Schottky diodes as varactor diodes.
     RF Gain: Optional RF attenuator control, useful when employing
full-scale antennas.
     Audio: Plenty of headphone audio, and will drive a small speaker.
     NS-40: Integrated into the PCB is Dave's famous NS-40 Class E
More info here:
     Crystal Controlled: The rig has a socket for the old-style FT243 crystals, plus 7030 and 7122 kHz crystals and included crystal adapters. If you have old 7MHz Novice crystals, you can use them with this rig!
     Output Power: Solid 5 Watts.
     No Toroids: No toroids to wind, all inductors are etched on the pc board.
     Keying Options: Straight key built into the front panel, just like the original Paraset! Also includes a 1/8" jack so you can use it with your favorite mechanical key, or an electronic keyer with an interface, such as one of these.
     Spotting: You can activate the crystal oscillator at low power to allow zero beating the receiver to the transmit frequency.
     Final Amp: Cool running robust MOSFET.
     Spectral Purity: All harmonics and spurious emissions are 50dB or more below the carrier.
Using a half wave 40 meters band dipole antenna fed via a one o one balun with 50 ohms coaxial cable, my 5 Watts output QRP transceiver provides good two way contacts under normal propagation conditions. My daytime coverage reaches all over the Cuban archipelago, and at night I can work all over the Americas, Europe, Western Africa. Under very good propagation conditions early pre sunrise propagation of 40 meters makes possible DX contacts with Japan, Australia, New Zealand and many Pacific Islands nations--- Now at the end of the show... a short form HF bands propagation update::. Conditions have improved and will continue to improve due a slight but noticeable increase in solar activity... see you all at the middle of the week edition of Dxers Unlimited next Tuesday and Wednesday UTC days  just after the half hour newscast here
at Radio Havana Cuba.
(Arnie Coro/R Havana)