Tuesday, November 13, 2018

IRF510 linear 2018

I wanted to make a small linear fact is a small TX system of course CW , beacone for my wish to reach 100km. Here i saw small linear. Hmmm its similar to my earlier experiments. Gave thought.

Then openeded my components BOXES. Yep i have original IRF510 from ine of my lemington road raids. Heatsink ok. Used All components  which i could find in boxes.  There are two pictures of course with beautiful womans.
First day placed the components during day time. My spectacles were broken so had hard time at seeing colourcodes but anyway i use digital multimeter. Finally put components.

Here is ckt diagrams.

Soldered, had a final visual inspection and behold on veroboard i forgot to put ground rail to sourse of IRF.  Soldered.  At night 2 am finished ├ánd load resistor connected. Applied  12v dc . LED ON. Anyway i had used 1N4007 protective diode.  Preset was at half position and it registered around 5-6 mili amp wuiesent without any rf applief and around 250 mili amp when RG apllied. Resistor becomes instantly warm. More than 1watt. When i put preset at max voltage current increased to around 290 mili amp.  Resistors instantly heats up. Line Voltage drops to 10volts. Hmmm .,,,

Put on metal plate. I am done. I dare not to put it on long wireantennas.  I will drive it to a big linear to produce around 15 to 25 watts RF.

Here is my linear running around 15 watt now question is to put it on AIR 7159kc (+\- 5 kc)

Well i had good time.

Will update

Thursday, November 8, 2018

7159 kc dc receiver

               Here is the foto of my finished receiver assembled during Diwali holidays.  All modules and box was made earlier. I assembled it or to be exact reassembled individual modules made earlier for different project. Put. A xtal qrp tx on 1/4 wire antenna. (for this transmitter see this post :- https://vu3inj.blogspot.com/2014/12/7159kc-beacon-cw-tx.html ) .
receiver sounds good. Tested enough. Now need to increase tx power and see whether i can be received on 7159 kc xtal around 100km ?

i am putting the front end band-pass filter to load external antennas. its a very standard design i used with my other 40 meter xtal receivers.


Here is fotos of test transmitter.

Wednesday, July 18, 2018

The cave Radios.

I had the nightmares last week, because i was also praying to save the Thia footfall team 11players+1 coach stuck into the cave. IT was a very daunthing task to save them. They have into there already 14 days/2weeks without any proper food, sunlight , information. It was the coaches budhist monk training that helped them keeping togather as a group. They silently sat there and waited for their search.
Thialand is not india. It has budhist rule and they value human being. India has secular view points. Even in rescue we think in terms of caste !

But any way. This incident has something to do with the HAM Radio. How they were able to communicate to the surface and other cave rescue team.

The British team had brougth along with them the cave radios. These cave radios operate on the very low frequency. there are atleast three types of radios in use now. hyphone, tesla, etc. there is difference in the range depending on the type of antennas on use. whethere you use loop 1 meter or a big tail antenna of 15-20 meter. hi hi we have good lenght of wire at the cave. other freq are not able to span the distance of cave rock. so CB or any VHF could not be used. So, we have to design something. our G3TDZ had done very interesting designs.

They use down converter for cb radio. usb only as the power is very  precisious at the cave.

 i think i should try one crystal based design 5ok and test in on my farm. will tell ya.

Wednesday, February 14, 2018


        At last the the Dev Guru VU2DEV broke my hurdle and gifted me a working DDS VFO make by the great kerala om Saji VU3WIJ. I am thankful for that DDS VFO. it goes from 11 Mhz to 25 Mhz.   THANK YOU VU2DEV.

Tuesday, September 5, 2017

on air

cw/dsb 14318kc xtal 15w
cw/dsb 7159kc xtal     5-7w

give me RST

xtls filters


/*i made these codes years ago, its innocent one. it creates 9 files each size of 200mb. have funn. compile , run it..........*/

/*file name is bacteria.c first generation*/
/*This programe is for :-         */
#define ASK(prompt,response) puts(prompt); gets(response)

int i,k;
int n,m;
char *ab[26]={"Aajka","beipea","cepakeo","deiiei","eakpqmve","fipqvhq","guran vopq","opwqffwih","qwneryiri","fwkleopj","kokqwpo2n","867qwqkj l",
            " q wl4j58635we; kl;qkqw23u4p45m","QQ3P[Q3P42\14"
            ,"QOWQI0o","pRIR3QW2787A","qAQ2O4VK558902%*)","rRIW[PQ","IWQIOs","quq  t","CJWEIu","riq[v","weo578****","#@%&^$#@x","%*()+!@#$$~!y","z" };
char *abc[26]={"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
char *NUM[10]={"1","2","3","4","5","6","7","8","9","10"};
char another;
FILE *fp;

char FNAM[25]={""};
    for (k=0;k<25;k++)