The Department of Electronics organized a Special Lecture for B.Sc. Electronics Semester VI Projects on 21st December 2011.
Participants present at the event were:
SJR degree College
M.S.Ramaiah College
Govt. Science College
Jain College
St. Claret College
Basaveshwara College
Sri Ramaprabhu, VU2DEV , the designer of Software Defined Radio Designer explained the synopsis of ISDR by power point presentation and demonstrated the working of the SDRs of 3 different varieties. Sri Sudhindraraja VU3PWT and Sri Vishwas.H.Jassisted Sri Ramaprabhu in the demonstration of SDR sets.
Sri Sudhindraraja VU3PWT, Sri Ramaprabhu VU2DEV, Vishwas H J
Recently the RnD team made a CW Keyer found in an old magazine.
Name: 73 Magazine
Issue Date: September 1999
Link to Magazine: Here
The CW keyer is simple circuit and uses the PIC16F628A. The components used are very less and can be built a very small general purpose board. This keyer works on the RC Clock and does not require an external crystal. The speed can be varied using the 10K Pot.
Below is a snapshot of the magazine showing Mr. Sudhindraraja, VU3PWT working on JOTA-40 Rx. and honorary mention Mr. Rama Prabhu, VU2DEV.
A rough translation (Please keep in mind that Google Translate was used ):
"When I visitedaworkshop, SudhindraVU3PWT and RamaPrabhuVU2DEV,I observedthe construction of atransceiverTRXJOTAintendedto the training centerof the "NIAR"(NationalInstitute of AmateurRadio)VU2NRO.Like thekitsBitXthisTransceiveris available intwo versions:forTRX40JOTA40andJOTA20meters by 20metersTRX."
Good news on the AD9833 DDS work from our R&D Lab.
FLASHBACK: Previously we could load the desired frequency using the PIC16F84A and display it on the Oscilloscope. (Refer to our previous post)
HOT NEWS: Now we can vary the frequency up and down. We have upgraded the Micro-controller to 16F628A as the migration is very simple. So how did we do it??? Refer to the code sample below and its very easy to figure it out. In case of any doubts, you can always leave a comment with your email or you can email us.
Also, suggestions and feedback are most welcome.
Circuit Explanation: We have used RA1 and RA2 as the up and down inputs. PORTB is used to feed the signals to the AD9833. Circuit diagram will be uploaded soon.
We wanted to construct a GR-40 Rx. for the purpose of demo to students. So we thought what best represents students. "EUREKA", why not use the Examination pad which is made out of stiff and tough paper cardboard. Every student uses an exam pad and if he/she wants to built it on an exam pad, they would happily destroy an exam pad for the joy of constructing a GR-40 Rx.
So we put together the GR-40 RX. on the pad with a BNC connector, square speaker (8 ohm and 10 Watt) and control knobs. The Speaker panel which consists of the DC supply posts, Switch, Volume, Tuning knobs and square speaker was mounted on the pad using aluminium rods. This model can be hung on the wall.
Mr. Sudhindraraja, VU3PWT attended the HAM-Fest India 2011 held at Kochi, Kerala on 10th and 11th December 2011. Here is Mr. Sudhindraraja. VU3PWT in-sight of his trip:
"HAMS from all over India and HAMS from other countries attended the HAM Fest India 2011. When I first entered the venue, the front entrance was so welcoming and after entering the reception area I was given a warm welcome and proceeded with my registration.
Mr Allen, VU3AUZ had installed his Midland Electronics exhibitors stall and I was welcome to join him to represent my company. All the products were in display along with our demo models. People were very excited to see the demo model of the GR-40 and were taking pictures along with it.
My responsibility was to explain to the visitors about the current technology of the ISDR and GR-40 Rx. All the HAMS and SWL's were in high praise of the GR-40 Demo model which was the highlight in the stall.
The event was a blast and a very memorable one. HAM FEST INDIA 2011 !!!!!!!!!!
Regards,
Sudhindraraja, VU3PWT"
Entrance of HAM FEST INDIA 2011 venue.
Stage setup
Allen, VU3AUZ holding and explaining the GR-40 Rx demo model
ISDR, GR-40 Rx box and demo model in stalls for display
Allen, VU3AUZ in the display stall
Sudhindraraja, VU3PWT in the display stall with the equipment
HAM Visitors checking out GR-40 Rx demo model
Sudhindraraja, VU3PWT with Rajagopal, VU2RDL
K G Natarajan, VU2KGN along with Sudhindraraja, VU3PWT
K G Natarajan, VU2KGN along with Sureendren, VU2SYT
GR 40 is simple single conversion Super Heterodyne Receiver. A 4-section XTAL ladder filter at 12MHz IF is used to select the band width. The receiver consists for two single side PCB assemblies namely GR 40 Rx. Main Board and VFO.
To cover 40meter band i.e. 7MHz to 7.2MHz, the VFO covers 5 MHz to 4.8 MHz. The VFO is buffered by a two-stage amp with feedback.
Original GR-40 Rx. in the box
The schematic for the GR-40 Rx. is shown below:
The schematic for the GR-40 VFO is shown below:
All the relevant files required to build your own GR-40 can be found below here:
Sudhindraraja, VU3PWT, an Amateur Radio enthusiast and a home-brewer built this table top version of the JOTA Transceiver.
An acrylic sheet was used to built the transmitter and receiver sections. A common MHz VFO was used as local oscillator for both transmitter and receiver. A 7-segment LED frequency counter display, volume control, speaker, MIC jack and tuning knob was mounted on a separate acrylic sheet. For TX. and RX., power and antenna switching was done by a D.P.D.T. relay.
Using this Table top version of the JOTA TRx., an Indonesian HAM was contacted.
Indian Institute of Hams will be conducting practical workshop on SOFTWARE DEFINED RADIO (SDR). It is a 7 Mhz receiver (Amateur Radio Band). Any Indian Institute of Hams member interested to assemble can enroll for this unique workshop. Workshop will be conducted by Mr Ramprabhu , VU2DEV Trustee & Technical Adviser, ofcourse veteran Ham.
Date and Timings
SATURDAY, 5th November 2011 between 1500 hrs – 1900 hrs
SUNDAY, 6th November 2011 between 1000 hrs – 1730 hrs
Note: All workshop materials like soldering iron, lead, required tools will be made available.
Once you assemble, download the software on your desktop and connect the assembled receiver to monitor the HF amateur radio band. Of course, a simple antenna is required.
