Friday, December 30, 2011

Special Lecture at SJR Degree College on 21st December 2011




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.J  assisted Sri Ramaprabhu in the demonstration of SDR sets. 


Sri Sudhindraraja VU3PWT, Sri Ramaprabhu VU2DEV, Vishwas H J


Sri Ramaprabhu is addressing the students



Monday, December 26, 2011

Saturday, December 24, 2011

CW Keyer using PIC16F628A

Greeting's everyone,

Top View
Front and Back View


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.

List of components used:

10k Resistor              - 3 No.
4.7K Resistor            - 1 No.
10K POT                    - 1 No.
10uF Capacitor         - 2 No.
0.1uF Capacitor        - 1 No.
0.01uF Capacitor      - 2 No.
LM7805 Regulator   - 1 No.
18-Pin Base               - 1 No.
PIC16F628A              - 1 No.
Speaker                      - 1 No.
General Purpose Board

CIRCUIT:

PROGRAM: ASM & HEX


list      p=16F628A          
#include <P16F628a.inc>

__CONFIG       _PWRTE_ON & _RC_OSC_CLKOUT & _WDT_OFF & _MCLRE_ON & _LVP_OFF & _BODEN_OFF & _CP_OFF

COUNT1 equ    028H
COUNT2 equ 029H
COUNT3 equ 02AH

ORG     0x00


movlw 07h
movwf CMCON

start    
bsf STATUS,RP0
movlw b'11111111'  
movwf   TRISA
movlw b'00000000'  
movwf   TRISB
bcf STATUS,RP0

begin  
clrf COUNT1
clrf COUNT2
clrf COUNT3

btfsc PORTA,2
goto dash1
call dot1
goto begin

dash1  
btfsc PORTA,3
goto begin
call dash2
goto begin

dot1
movlw d'12'
movwf COUNT1
redot 
bsf PORTB,3
bcf PORTB,3
decfsz COUNT1,f
goto redot
call pause
return

dash2  
movlw d'37'
movwf COUNT3
redsh  
bsf PORTB,3
bcf PORTB,3
decfsz COUNT3,f
goto redsh
call pause
return

pause  
movlw d'14'
movwf COUNT2
repa  
decfsz COUNT2,f
goto repa
return

end









Thursday, December 22, 2011

Belgium Magazine appearence

Greetings everyone,

The following is an article which was published in UBA - Belgian Amateur Radio Society club magazine. 

Link to the article: Here

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 visited a workshop, Sudhindra VU3PWT and Rama Prabhu VU2DEV, I observed the construction of a transceiver TRX JOTA intended to the training center of the "NIAR" (National Institute of Amateur Radio) VU2NRO. Like the kits BitX this Transceiver is available in two versions: for TRX 40 JOTA 40 and JOTA 20 meters by 20 meters TRX."

AD9833 DDS: Update



Hello everyone,

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.

ASM code: Click Here

Code:

"


list      p=16F628A            
#include <P16F628a.inc>  

__CONFIG       _PWRTE_ON & _XT_OSC & _WDT_OFF & _MCLRE_ON & _LVP_OFF & _BODEN_OFF & _CP_OFF
temp1 equ    028H
cnt equ 02AH
count1 equ 02BH
count2 equ 02CH
count3 equ 02DH
LSBreg1 equ 032H
LSBreg2 equ 033H
MSBreg1 equ 034H
MSBreg2 equ 035H
ORG     0x00 ; processor reset vector
 
movlw 07h 
movwf CMCON
  bsf STATUS,RP0
movlw b'11111111' ; RA0..RA7 inputs
movwf   TRISA

          movlw b'00000000' ; RB0..RB7 outputs
movwf   TRISB
bcf STATUS,RP0
movlw 0x7F
movwf LSBreg1

movlw 0x00
movwf LSBreg2

movlw 0x4F
movwf MSBreg1

movlw 0x0F
movwf MSBreg2

call main1
main2 call Delay
btfss PORTA,1
call inmsb
btfss PORTA,2
call demsb
goto main2

inmsb incf MSBreg2,1
call main1
return

demsb decf MSBreg2,1
call main1
return

write1
movlw 8
movwf cnt
send_loop
bcf PORTB,4 ; assume zero bit, AD9832 SDATA pin = 0
btfsc temp1,7 ; check MSBit of 8-bit word
bsf PORTB,4
nop
bcf PORTB,5
nop ; make a pulse on AD9833 SCLK pin
bsf PORTB,5
; rotate all 8 bits left (through carry)
rlf temp1,f
decfsz cnt,f
goto send_loop
return


Delay movlw 0x11
movwf count1
movlw 0x5D
movwf count2
movlw 0x05
movwf count3
Delay_0 decfsz count1,f
goto $+2
decfsz count2,f
goto $+2
decfsz count3,f
goto Delay_0
return

main1 bcf PORTB,6

movlw 0x21
movwf temp1
call write1

movlw 0x00
movwf temp1
call write1
clrf temp1
movf LSBreg1,0
movwf temp1
call write1

movf LSBreg2,0
movwf temp1
call write1

movf MSBreg1,0
movwf temp1
call write1

movf MSBreg2,0
movwf temp1
call write1

movlw 0xC0
movwf temp1
call write1

movlw 0x00
movwf temp1
call write1

movlw 0x20
movwf temp1
call write1

movlw 0x00
movwf temp1
call write1

bsf PORTB,6
return

end



"




Friday, December 16, 2011

GR-40 RX. Board Model

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.


Layout view of the GR-40 Board model - View 1

Layout view of the GR-40 Board model - View 2

Final GR-40 Rx. Board Model hanging on the wall
GR-40 Rx. Board Model
Testing of the GR-40 Rx. Board model

GR 40 Receiver video

Here is the video of the GR-40 demo model in action:




Please leave us your suggestions and view on the model.

Thank you,
RnD Team

Monday, December 12, 2011

HAM Fest India 2011, Kochi

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
                               


Tuesday, December 6, 2011

GR 40 Reciever


GR-40 Rx made for Demo purpose by RnD Team



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:

GR 40 Rx list                             :Click Here 
GR 40 Rx Schematic                :Click Here

GR 40 VFO list                         :Click Here
GR 40 VFO Schematic            :Click Here

  For any help required please contact us through email.

Friday, November 25, 2011

Table-top version of JOTA Transceiver built by Sudhindraraja, VU3PWT

JOTA TRx. in a box
Table-top JOTA Transceiver


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.

Tuesday, November 22, 2011

Malabar Repeater Inauguration at Payyannoor, Kerala

Malabar Repeater Inauguration at Payyannoor, Kerala

Inauguration of the repeter by Ramaprabhu, VU2DEV


Visiting Repeater QTH


Audience attending the Repeater Inauguration




Monday, November 7, 2011

Pictures of ISDR workshop held at Indian Institute of Hams on 5th and 6th November 2011

Introduction to ISDR

Students and Team members

ISDR kits handed over to Students

Assembly begins

Team helping students



Teams setup of the ISDR

Students try their hands-on with ISDR


DAY 2 of the workshop

Team members helping the students

Team member testing the students ISDR

Finished ISDR of a student

Student tests his ISDR

Friday, November 4, 2011

Workshop at Indian Institute of Hams

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.  

NO LICENCE REQUIRED TO MONITOR THE AMATEUR RADIO.

Address
INDIAN INSTITUTE OF HAMS

Gate No.2, 2nd Floor, 
Sree Kanteerava Outdoor Stadium,
Kasturba Road, 
Bangalore - 560 001
Phone:+91-80-26664501
Cell: +91-9448302677