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++)

Sunday, August 13, 2017


For long tome i wanted to see what is inside the analogue VHF cable tv booster amplifies.They were in great demands before the digital system kicked in.
The start of the VHF broadcast TV started around 1980 as home to home a 3 hour picture programe. The cable guy has the VCR and he connected the cable. That cable brought the single chanel and we sat and saw the TV. It was particularly aimed at the house-wives and childrens. The small players mush-roomed.

Then next stage was the day and night time pictures. This was a monthly rental.

This developed with multiplayer/providers in a single city. Then came the satellite TV channels and permanent studio environments. It removed the small time players and now a single entity of the providers grew like a monopoly.

Then came the paid channel concepts and presto the industry was born. The variety of digital and analogue, free and paid channel setup came, big dish. Then ISRO also jumped in with its new technology and it was the breakthrough.

At this time the cable net work developed in its entirely depending on the big studio where multiple saterlite dish antenna and receivers were housed and from there all the city was covered. At this time this VHF boosters were used.

Suddenly the satelites channel become paid, it become digital and cabling was changed from lowly RG58 to higher quality one.  TV become multichanel. 500 tv chanel, vhf-uhf-shf. And that's it.

Those TV booster become obsolete. In the EU peoples used the satelite receiver as AMTV receivers for their 10GHZ (?)band etc. But, we do not see anything of that sort here in india. peoples do not move nor reached to VHF.

Anyway i bought the box for its box values. I will tear it down and house a small QRP receiver/transcever  for my portable single freq use.

oh yeh, i got BFW15a and c2725 and 7 ferrites beads. i bought it for only 1 $ (Rs100/-) .

Till than folks let me work, then talk......

Monday, July 4, 2016

LEO Satelite-1

Recently few engineering students publicized that they made a CUBE satelite and put into theorbits with help of ISRO. Their website is at   they described their tale, their institue is very proud, they got many appalause from lots of politicians, dignitaries their fair share of 5 minutes fame. Wow our kiddos did great things.

But, there were few critical voices, who analyzed and considered that in europe and amerika this cube satelite project kits is freely available and ours did not differe. Few friends requested COEP to provide the close up image, ckt diagrams , details of satelite but it is not revealed.  Lots of geeks pointed out the anamolies in signals uplink downlink maintenance of ground stations etc. In those opinion it seems it was a hobby project in big propotionals where every one is happy except the end users. We the ham.

In this entire project the ground station relaity were never considered. Freq used is in UHF. How many hams have ful fledged VHF,UHF stations capable to cath up the birds ? very few. Modulations is FM BPSK , which is very wrong due to doppler shift. Even the pure carrier on-off cw might have been good. 

Ground stations needs some yagi beam antenna. Now a days dongle is available and with computer software we can decode many modes and of course cw also.

I raised the question, how many hams, or ham bodies were consulted before making the project ? Ham resources are free but limited. Atleast any institutions making any project should put their proposal, ask for guidance , opinions to groups of hams, institutions, clubs , experts etc however they are not legally required to do so. If you make something which is not usable to the end users ( we hams or any students, common man then what is need of blocking one space in LEO, making hue cry, spending 7+27 lacks money. India is a poor country and we do not have luxury to spoil resources. LEO orbitt is already full of scraps why put more SCRAP ...
Anyway enough of oil-burning.  The life time of this satellite is only 6 months to 1 year and it will be history. Forget them and Now lets go to technicalities in simple terms.


your can buy ready made from

Cube satelite is just a simple cube. outer surface contains the solar panels. Batery,4watt. It might have antenna, becon, transponders ( budged ?), camera, azimuth level control , sun sensor, communications channel. on board computer etc.
The main problem is to fit all this elements of our choice into a small size cube without increasing weights. Second is fabrications. It need precise engineering. Wth advent of CNC, 3D printing it has become easy. All material should be radiation hardened.

If you have enough money every thing is cheaply available off the shelf and ready made in amerika, Europe.

 We are used to poing our dish antenna to the satellite and receive TV, NEWs Entertainment. They are in Geo-statitonary orbit. Antenna remains constant. Satelite and earth moves with same speed. But LEO satelites does not give constant view. It moves around earth in elliptical orbit. Its speed and earths are different. At one point they are very near to the earth 300 km and at other point they are far /1200km . So, when they are near we can receive good, work them with very low power transitters. If they are very far from us they become useless.  We choose this orbit due to low budget, easy of ground stations connectivity, low cost equipment, easy to put into orbit ( rides on some big rockets at no real cost.) and we can make it at our school, home with easy.


How do we know when satellite will pass near our place ? There is a software which predicts where our satelite in interest is. All satelites are being monitored by amerikan NORAD. We can download the latest data from their website. As many forces takes place and our satelites do not have boosters, fuel rockets to correctly maintain its course they are constantly being monitored by USA.  Every object in the space is given a SSN number.

Best software ORBITRON is from our own ham xxxxx ,he made it when he was just a kid. Better than indian kids. Anyway from his website get a zip file. There will be 32bits , 64 bits system also. ZIP are non-install type which works without any installations, good for many fricking new computers which requires fucking micro-hards software signature verifications certificates ( linux is good to opern source and hams).

RECEIVER -Decoding Software.
Hams use all mode FT897D. Its compact & best rig for portable use. and it operates from HF to VHF,UHF. But, it is costly.

On cheap side, It is reported that dongle is also good with SDR sharp software. It can decode the signal.  Actually you need a yagi, receiver, the base band file to be decoded by software..... or yagi, dongle, computer, software and everythign is fine.

Put a simple yagi pointing up into the sky, try to see in computer. As actuall pass is very short.
Consider the satelite as bird. If a bird is flying above your head, you will be seeing it coming near you, over your head and then going afar. The same thing happens. To identify the birds you need to let it come into the visual range. Same thing calles as foot print of satelite.
For new hams---As listenign satelites requires some practical guidance, you got to ask clarifications from somehams who has recently worked these satelites.


In the past it seems many hams have reached to the sky. have a look.  In my opinion our VU2MUE has done good works on satlites, APRS, digital communications. He is at Delhi, look out to his website and facebook page for more informations. There are many other professional who worked with NASA, AMSAT organizations i.e VU3GEK, ganeshan, in fact he is a good in sat tech. And many more


Also do not forget to look up on,   they have good informations. There are dedicated websites also.

Wednesday, May 11, 2016

40 Meter Receiver (7159kc)

Few days ago a friend asked me about the simple receiver to practise his CW Skills. Well, i have done few experiement with poliakov receiver and they have given a repeatable , proven results. I scanned indian products and could not find any thing for the small kids, new hams or something very basic minimalist, cheap devise. So, I filled in the space. Its better than pixie, tixies, foxx etc but less than well made DC receiver . Brainstorming started, I thought let's re-re-invent the wheel.....
here is the result

This requires minimum of time to make and its up and running within hours. It can be used to practise morse on air. It will certainly not bring the good dx nor it is frequency flexible.

See my previous posts, you will find many experients on this subharmonics receiver. It is still in development stage. You can have dip file from me. Just drop an email. I am making a suitable transmitter. In my mind is two way. One to use this LO and then use the doublers amplifiers to arrive at 40 meter so the hard to find find 7159kc xtal can be avoided and further 3560kc resonator can be used to give flexibility of freq. working on it. Tx might be three stage 3watt, along with relay change over etc.  Another tx will be using 7159kc xtal , class e two stage to arrive at 3watt.

Lets begin::: It all began with this ckt, have a good look. From this all other things are derived. First transistor is an RF amplifier. Two back to back diodes forms the sub-harmonics mixers. Second transistor is AF amplifier. The gain of This AF/RF amp depends on Rc/ Rb. If you find the gain is little low try experimenting with it. 470k/4k7 will give gain of 100.  The choice of transistor will determine the gain as well as noise. The RF transistor should have high ft ( gain bandwith product) that way it will produce good signal. In my experiments I found that bc547c, bc547b gave different gain. 
Small whip antenna works fine. For higher frequency please use some broad band transformer coupled RF amp. That will give good result in 20 meter. At present this ckt is good enough for 40 meter.
The diptrace schematics screen shot.

This is the diptrace pcb making software , This time I took time to make the schematics on this. EArliers I used make by hand and then scan. I realized to make a professional grade pcb, good quality image and parts making the pcb software is a must.
The ckt diagram
List of components
# RefDes Value
1 A1 whip antenna
2 C1
3 C2 100p
4 C3 100n
5 C4
6 C5 100n
7 C6 10 mfd
8 C7 10 mfd
9 C8 100p
10 C9 100p
11 C10 100p
12 C11 100n
13 C12 100  mfd
14 C13 1000 mfd
15 C14 33p
16 C15 10 mfd
17 C16
18 C17 100 mfd
19 C18 100 mfd
20 C19
21 C21 100n
22 D1 green LED
23 D2 1n4148
24 D3 1n4148
25 D4 1n4007
26 J1  speaker out put JACKPIN
27 J2 dc input JACKPIN
28 L2
29 L3 
34 Q1 BC549C rf AMP
35 Q2 BC547B af amp
36 Q3 BC547B Oscillator
37 R1 470k
38 R2 4k7
39 R3 470 ohm
40 R4 2K2
41 R5 120k
42 R6 2k2
43 R7 100 ohm
44 R8 120k
45 R9 2k7
46 R10 100 ohm
47 R11 47k
48 R12 470
49 R13 10 ohm
50 R14
51 T1
52 T2
53 U1 7805
54 U3 1/2 TDA2822m
55 Y1 3579kc
56 Y2 3579kc

Note of TDA2822m,

I always used LM386 but somehow I am finding difficult to get a good chip. All Chinese chips are faulty. So, tried TDA2822m  an 8 pin DIP ic. It is good one. It contains two amplifiers. This IC is a low voltage, low power  AF amp. So, use 4 to 5 volt maximum. When used with 12volt supply it starts heating up To reduce heating on IC, I used a ballast resistor of 200 ohm ( 100 ohm 2watt + 100 ohm 2watt) , so it stopped heating up. Remember this thing.  Only one part out of two is used.

Note on Antenna.

For making pcb from schematics , I put a two tank band pass filter, otherwise single tank with whip antenna is sufficient for all purpose.

Note on the Xtal Oscialltor- 3579kc

we need very small Rf injection to the diodes so single transitor osc is used. There is shown two coils and two xtals. I put it there only reason if someone wants to modify experiment , the same pcb will be useful. F6GQB. So, I can get 60k shift , more than enough for this set-up.  Except this two square I have not hidden anything. Only this squares have few extra empty parts.  Only single xtal is used, No RFC used.

If anything is missing please let me know.
You can make it, but remember its still in development stage. When I first put it on facebook there was two errors. one transistor part was wrongly labeled. And 12 volt and 5volt lines mixed up at 2822m. So, ckt on this blog should be final.

THE RECEIVER CKT IS FINAL. there will be no modifications. but revision of write-up , addendum will be added later on.

Input Band Pass Filter modifications. As of 17 may 2016 Modified the input filter system. Put fixed inductor 2.2 micro hentry with 215 pf =( 100p || 100p) + 180pf , tap taken from junction of both 100pf. The RFC of 2.2 micro henry can be used ready made or  made one 9 to 10 milli-meter dia plastic tube, I used felt pen, 30swg around 22 to 24 turns close wound, length will be 10 to 12 milli-meter.  Measure it with LC meter.  Plastic tubing former was around 3 cm long.  Will upload close-up fotos soon.

Receiver sounds good. Housed in the home made box. Other modifications like painting, putting nut-bolts that will happen as per need but electrical ckt is finale.  Am breakthrough is very minimal. AF filter might be a good idea. But the simplicity beats all. Make this receiver and please wait for compatible transmitter.

so, till then enjoy, the wheel has been re-re-invented, take a ride.
de vu3inj.

NB;- you may write down few words please.