Tuesday, February 24, 2015


I will be starting my journey into the world of micro-controllers ( in fact small computers) with ARDUINO UNO R3 & arduno pro nano break-out board with FTDI ( it connects computer usb to pro nano board).

I will take a short cut. A friend will help me with ready made ATMEGA328 programmed arduino with software of DDS VFO. Then a friend will help me build the arduino from the scratch.
Then I will buy some nano boards or make arduino from scratch for some friends.

First step  first

I down loaded the software from the http:\\arduino.cc version 1.05. Its old version okey as my 2g dongle permitted me to down-load 92 Mb data in 2 hours. Ha ha a very fast one.... Chose non install version i.e zip file so that it can run on note-book also.

Now time to have 5volt power supply for nano board and some ZIF and printout of tutorials.

Second step :-
Here is the  close-up  of Arduino Uno and Arduino nano...pin outs........

Saturday, February 21, 2015


Recently out of urgent need and to revive the long lost dream of programming 8051 board. I realized that game of the day is the ARDUINO platform.

This is  a tool which school children plays easily.

This is the platform the geeks are possessed of.

This is the device many commercial manufacture makes their product.

This is ultimate device to entering into the digital world without learning any programming. You directly benefit from the experience and expertize of other hams who have been there. This is a very helpful ally for ham in making digital project.

Our simple ham needs are ?  DDS VFO control, CW Keyers/ deconders,  AVR programmers to re/program the PIC. Frequency counters, Temperature control , Power supply regulations.

Lets begin

I put request in the homebrew fourm. The reply and help was overwhelming. Thanks dudes.

" Once i have arduino uno or nano then no need to learn anything.... just plug it pass the already available codes from web/friends make dds vfo and be on air. and if still blessed then make some for other friends also"

Another friend also reiterated the fact this world  :: Dont worry its easy once you learn arduino... dont try to learn the codes... try from examples...
My expert friend from Mumbai offered to make the ARDUINO from the scratch i.e AtMega328.

To do so, you need any one of the following hardware,
1) AVR programmer,
2) another arduino board
3) parallel port or a usbasp programmer.  So tell what do you have with you?

Well I said I have nothing. He smiled and said do come visit me. One day during my visit to metro we will go to lamington and buy some devices. I hope to learn from him also,

It seems I need to do this way.

1. Install Arduino software from the arduino.cc.
the latest version is 1.6 but 1.05 will be also fine for my applications. There are two varieties one install and one zip format about 100mb.

2. second I will need some USB cable or FTDI ( in simple laymans terms to pass the message from computer USB to micro processor. This will be needed if I use pro-nano board or atmega in breadboard. There is two version of this FTDI. one with 4 pins and one with 5-6 pins. Another friend asked me to go for pro-nano as it is cheapest can be put into the projects board permanently and do all the work of ARDUINO. Also use 5-6pins FTDI, there is software reset.

3. ARDUINO UNO:- This is general purpose board with all the flexibility and necessary connectors and hardware. Compared to homebrew board its more sturdy. Cheap indian board also can be used.

This UNO can be used to program the raw chips, can install bootloader to make another arduino ! wow, we can test the program before its burned into chips permanently.

In the nut-shell you need atleast one working and talking arduino to make another arduino... he he to make curd you need curd... its that simple...

4. From net you have to down load the program. This are called the "sketches". They are written in sub sect of C language. Most of peoples know the C-lang and can understand. Why C ? its hardware we are dealing with and most of hardware work is in C. If you don't know any C. No problem. Just get the sketch. Now compile it in the IDE. The software you down loaded into the computer for running the ARDUINO. Open your sketch with IDE. Now compile it. From the computers USB it will travel to its destination the Atmegachip in the arduino board. Now your board will act upon the instructions of the Sketch.
Disconnect the  Arduino board Everything is done. Your Arduino board / breadboard atmega is ready to rock...

5. Finish the soldering etc put it in the nice box, it will drive the real world applications. And project is finished.


What happened to the computer, usb cable etc ? Well forget it till next project. Here tragedy is that even you don't know what's written in the sketch ? As its not needed unless you want to modify something in software.

Its a very modular operation. Compute knows whats it doing, FTDI know whats it doing. The ATmega knows whats it doing. But, In order to use them we never need to know what they are doing. he he.

Enjoy :- nothing can be more simpler than this... 

Meanwhile another friend from banglore has also promised to gift me some arduino... just to spread the benefit to my other ham friends. Well agreed. Waiting for it. Personally I am against accepting anything free. But, in ham radio ,If something keeps my soldering iron hot, my projects going, people benefit from me, then I accept it.
Readings about ARDUINO is going on. I found many interesting articles. When I will get hardware sure to post more fotos and making process as demanded by 2DEV...
You peoples are really good ones. I just do cut,copy,paste and add few words to make it understandable to layman/first brewer...so no originality or credit goes to me.

To be continued.....


Sunday, February 15, 2015

On air, part-2

To be on air what we need ?
1.Atleast 20watt QRO cw with {14318kc xtal or VFO on 20 meter}.
2.A dipole higher than 30feet atleast.
3.A good DC/Superhet receiver with QSK...
4. Well ventilated power source atleast 28 vdc @5amp and 12vdc @3amp.
This the hardest lesson I have re-learnt.
If you are lucky you will be getting good regular contact with 2watt ssb also. Remeber if you had been lucky after getting the ticket (license)  within 2 years you might have got some homebrew/commercial rigs...
I have suffered and then understood with the help of elmers... If you are not coming on air and could not find the problem with you.... here is the solution in clear words....
Once come on air with cw and the jinx will break...ssb will be next....the same linear, antenna and power supply can be used for SSB trx. What is the cost ? Not more than 1000/-. No need of big instruments, just multimeter, rf probe, dummy load, frequency meter. Dude just scroll back in the blog....you will everything about tx antenn making procees...
I see peoples suffere due to lack of good working equipment /not enough money to buy commercial rig /no will to be on air/lack of support etc.  Please don't suffer and come on air quickly.
Many peoples will say about lots of rigs/homebrew etc etc...they are also ok, also right on their on their view point. .... well I have nothing more to say, no more to comments etc.....73....de vu3inj.....indrajit....
Just be on air. I will try to be on air on 14315kc around 5pm to 7pm daily...

Tuesday, February 10, 2015

CW TX 14318kc ( second)

Today I promised one old time friend in exchange of the old BC radio to give atleast one 5watt , 14318 kc based CW transmitter. Hope I will be able to put it up within a two week.

It should not pose any problem as all the modules are learn by heart.

Lets hope it works out for him as well as me.... Atleast this way he will be able to be on air and I will good karmic benefit....

Reason I am taking this effort is a very simple he is willing to work CW... I have not mastered the bitx... so not making it...  Now a days peoples prefer the SSB and CW is looked down but I like CW ....So as a bonus will try to make the linear also.....

I have promised what I can make easily. I will make just full ckt... He needs to find the old computer heatsinks with fans....he is also required to do some soldering and cabinet building,  power supply making, antenna, will try to incorporate some sort of antenna tuning indicators... etc... this is a little tough task  ...

1. 28-0-28 V ac, @5amp
2. 12-0-12 volt @3amp
3. Small cooler fan.
4. Antenna & wire.
5. Morse key.
6. Receiver and changeover things..

Here is the picture of that :-

two linears
The two modules shown in the black rectangle is the  small linear amplifier. Marked (1) & (2)...

One friend said after some time it will be boring. Right 100% but this will put you atleast on air easy and low cost. What else you need ?

16 February 2015 :- Today I tested one linear board with crystal oscillator and a tuned buffer amplifier. Wow ! it can directly drive the 5watt lamp with brilliance. Humm power is very high. It can be used as a standalone transmitter without using the after burner. There is no self-oscillations. Feedback is there.

DC current/voltage readings were crazy. Set bias preset it for idle current of 60 mili amp.  On applying the RF and increasing/decreasing ( I had used preset in buffer amp), current reached upto 5 amp. Even on zero gate bias i.e. class-c amp it takes the 1 amp... Too much power.

Need to reduce the gain. Will put one 100 ohm in the tuned amp, buffer amp and also 4k7 accorss the 2n2218 amp.  As I want to use it an Intermediate linear amp to drive a big linear about 15watt.... working on it.... As of made the changes. Now the fan using the LM7805 and side tone, DC /RF indicator LEDs need to be fitted only. Power Amp and DC receiver will take some time. But meanwhile this cw-tx will be ready for its journey....

24 February 2015

With the help of VU3INK, om KISHOR it was tested on air and the report he gave me 579 and 547. Good for  1.7watt RF power with 3 swr. Frequency he tuned was 14314kc.

My Advantage is 33ft high antenna.  Wish my end user reads my blog and follows my tips particulary about antenna. I advise him to use the transformer based well cooled 12@ 3amp power supply only. No smps please.

So, the wheel has been re-invented it will be used by my friend.



Renewal of Ticket

Today I got the license renewed for my lite time. That means till I die or it is recalled or I upgrade..... Really feel nice..... Now, time to print the QSL cards..... This was my first reaction on10 feb... I put the license in the locker. Today on 13th feb wanted to put this here in blog and I saw something different.......

I am just puzzled why upto 2017 I paid for life-times fee i.e 2000, paid penalty for late renewal.

Who is playing with me ? May be its clerical error. May be its practical joke on me.....  I never heard that license is renewed for only Two years... IMHO instead of adding 20 years s/he added just 2 years.

This is not the first time Min of Com. played jokes with me... When I applied for the license my result was mixed up with another person. he received my letter. I received his result. Instead of giving me my letter he sent it demanded that I give his letter. What a jerk he was.... After that police enquiry, verifications , I paid up fee it went missing. Then once again paid-up  fee .Then I had to wait aobut 5 years. On insistance of my local Member of parliaments personal visit to WPC. Yes sir she visited personally to WPC... Atlast they assured I will get my license in 11 weeks, but it became just 11 months.

When I applied for the renewal  recently. For a year they just sat on my applications, Then took one years to ask me about the fee. Then they took one year to give me license. Even that is given for 2 years... Who is messing with my life.....

NO need to be Happy. No need to print QSL card... No need to Thank God.

If you are listening, hear that :: God you sucks..... better get your nappy changed......

Wednesday, February 4, 2015

14194kc DSB transmitter

The most of beautiful band for me is the 20meter. I fell in love with it reason most of the time I can get plenty of the station for listening DX and local. Some are QRP/QRPp/QRO.

Its time, I make the DSB Modulator and be on the air. Lets see how much I fare.
Started the 2Watt linear.

This will be my third prototype. First stage is the 2N2218, Second transistor is IRF510 both working on the 12vdc. This time I will be making the power-supply little up 14 volts. ie LM7812 plus LED.

Plan is to drive the VXO of 14318kc, one DSB 14194kc, 3.68mhz ceramic VFO plus Quadrupler. And the DC receiver integrated with it.......

VU2ESE has designed this linear and it gives about 5watt when carefully made. But ,I call this 2watt as to me it gives me just 2watt without any special care. Happy, this is best for our use.  I could have tried broadband RM96 1watt amp, but that needs more toroids/components
my toroid/ferrite source ( I do recommend VU2PTR for toroids)  (For balun core I bought from tpsonline )

Here we can use the simple plastic pipe for IRF510. And just one balun for its driver. For RFC use the CFL lamps cores. What else you want ! This ckt is best made on the veroboard ( Yes sir !).

A small heat-sink is needed. 2inch by 2inch (5cm by 5 cm square or rectangle aluminum will suffice). But don't over do here. use small piece as heat dissipation will be low.

One thing I remarked that we need 24swg copper wire with just 2-3 twist perinch for biliar winding. When I gave more turns about 6-8 turns during the winding (sliding the wire from cores) I feel insulation was cracking. not joking. I realized the mistake but somehow if this does not work I need to rewind the toroid for IRF640 ( the after burner power amplifier)

05-feb-2015. Finished most of the components. Winding the second set of coil incase the first coil does not work as it has low number of turns. Prepared the heatsink from aluminum. It was in L-shape. Cleaned it. Flattened it with the wood batten and small hammer (250gm). Then with the help of Jig made it into the U-shape. Filed the aluminum surface clean and fat. As the transistor has to made the contact with it. So, it must be flat atleas the contact area. Then put the drill. The heatsink should be outside the pcb not near or on the 2n2218 transistor. Otherwise feed back may arise. I did not had the insulating kit but will use small plastic piece on top bolt to isolate it from Vcc.
Lets hope it works as I am trying an old tech in the days of the DDS Microprocessor controlled VFO........

But my hunch has proven right sofar.....this will also work

All the fun is in making and using it to drive a big amplifier. Yellow are the biasing network for IRF and 5volt dc supply. In blue,The crown heat sink is the driver transistor. In he tblack is the IRF amplifier stage. In corner  black LED to indicate the DC supply...........
One thing I noticed that in the previous two attempt the preset was atleast 2 hole apart from the two 100 resistors... here that is the mistake. So if you are making atleast put the preset 3-4 holes away from the 100 gate resistor. This way during the tuning the screwdriver just don't hamper the coil.

Please use the dedicated LM7805 here. As the work is in progress  at the input and output we need to put one 470 mfd, 25volts each. This way It gives a good stable 5volt. There is one LED placed so it burns the voltage during switched off and reminds me that there is voltage.

I have made a point to add atleast one LED per board so that quickly I can know atleast there is voltage and power supply is not at faults.....

Now the back side of the vero-board.

Here it is important that the IRF510 is soldered in the back side to reduce the lead length. IRF is not inserted into the holes. Just placed over it. If the lead length is big it will sure to oscillate, be it in the copperboard, etched pcb or any damn thing. Make sure the lead length is small. also notice the gimmick 10 ohm resistor on the gate of IRF510. I have also used the 100k+0.1mfd capacitor for negative feedback. This reduces the possibility of the parasitic oscillations. I did not have the insulation kit for transistors, so using the mica washer only. Of course the heat conducting paste is liberally applied. The gates impedance is 100 ohm so it needs more drive from 2n2218. That's okey.

I could not find the round ferrite core used in the CFL lamp. So used its transformer by breaking its half E core into a C and then placing a small slab on it so it becomes sqare bobbin. I also liberally applied the plastic adhesive used in the water pipe / plumbing.

work is in progress will be update from time to time.... whatever the outcome.....

07 Feb 2015.
Working on the Quadrupler and Amplifier. May be today or tomorrow it will be ready. At this time only one band will be operational. But will make it for two bands.

3.68 mh Ceramic VFO + Quadrupler is almost ready. Two Coil needs to be tested/ tuned for 20meter band.  One small amplifier will be added which  will drive a CW as well as DSB modulator plus DC receiver. Lets see......

Actually I wanted to make this for  20 & 40 but in a bit hurry to be on air.... anyway will make dual band also. On searching the net I found somedifferent filter which has the 50 ohm terminations impedance using the capacitor divider method. That's good. So, we don't have to put a tap, that results in physically strong coil. When we put the tap it slacks a little bit.... whatever works is okey for me. So when you re-produce make sure it  works for you.... I don't intend to make another or repeatable thing. Each prototype will be little different, learning from failure and success of the previous modules and new information.

The modules first tank i.e quadrupler required extra 47pf. That means it required (47+68+150)=268pf total with 13 turns 20swg copper wire wound on the 1/4" drill bit. I chose the dril-bit as it is a very precise tool then lots of other available items like sketch pen, plastic tubes etc.

On second thought I think a small 2db pad will solve a harmonics problem. 470 ohm 10 ohm 470ohm preset to control the RF. This was quadrupler get minimum power required without producing excessive harmonics. I will not put the signal directly to tx stage. Instead make one class-A tune amplifier with emitter degenerations. So that harmonics are down further. Will also use more filtering at the  small linear stage.

One friend recently asked why taking this much pain. I said I have in the last year spent atleast 20k in buying old marine receiver ( lasted 6 month), LRR40 receiver ( that piece never worked from day one), VHF DR150 that guy cheated me. So I don't trust. I will not buy anything from the hams. Only VU2PTR & VU2KD was able to give me something which worked as they claimed.

So I am making this much effort to be on air. First will be the CW/DSB tcvr 15watt. Then will move towards the other band.

The receiver was tested with this quadrupler module. It gave me good quality signal in speaker even with 15cm wire as antenna. It has too much gain so there is need of proper shielding and filtering plus 3db resistive pads....


At night time again tested the linear module. There was short developed due to the that green capaciotor. Removed it. There was no connection/ dry connection on Vcc rail....
need some work..... there is some carrier leakage...

This is the first time TA7358Ap module is leakage of RF. On verobaord it was very nice. It might be due to the  copper planes instead of small pin socket...(. it needs some pads / resistor to curb the leaks...)


finally plugged the problems. At the 150 mw pre-driving amplifier on the  DSB modulator put one 10k resistor across the 4:1 transformer. Then things settled down. It still producing more power so will have to put some pad at the IRF510 output. Signal is very clear and clean. Will put one filter after IRF510 amp... Starting to brew the after burner (using IRF840) and the cabinet, VFO. So I will have three things on this TX/ CW full band, DSB on 14318kc xtal and DSB on 14194 kc ......

Half success...One day one day, I will be transmitting ham....

work in progress........

(this ends here, next will be actual on air test and other things.....)


( Till August 2015 not tested it on air. oh the damn 24 Vdc power supply.Will drive a big linear with it. )


Monday, February 2, 2015

Small Signal Amplifier, Buffer Amplifier

On many occasion new friends ask me this....I need some sort of amplifier which does not oscillate, it shall be easy to tune, should accommodate small as well as big signal , low noice. It has be used in the front end of the DC receiver. I need to drive a linear, some measuring instruments,i also don't have & not able to finding RF transistors etc.

Asking for all these parameters /constraints it is  like finding a perfect woman on first date. But, anyway here we make some trade-off and it works out. The small signal  amplification  in TX or RX needs more care. To arrive at first 1 watt power is little harder. After that its relatively easy to achieve 10 to 50watt with careful choice of the linear devices and Vcc.

Small Signal RFAmplifier:-

This RF amp is very wide. Important is that you choose the transistor wich can dissipate upto about 30ma dc current without any problem i.e metal pack So 2N3866 fits the bill perfectly. another suitable candidate is 2n5109.

Limit the current to 10ma and garden variety BC549c can do the job for you. In bc547/8/9 variety this transistor has highest gain. Another candidates you should look for are in C series C945 etc C2570 but it should be able to sink this current.

"ft, beta/gain, current, this  three parameters."

Balun core or toroid is a must. I have not used plastic former, but you can give it a try ! In the fig1 at R2. For transmitters don't put any resistors. For receiver, to limit the current use 100 ohms. ...
This buffer amp can be used after the oscilator. It gives good isolation. In the BITX version 3 its used as receivers IF stage. Its input resitance depends on the  input resistors value , say from 220 ohm to 1k ohm. Here transistors used are, first BF194b and second BC547b. Vcc can be from 5 volt to 12 volt. D is 1n4007 diode. Output impedance depends on the emiiter followers resistance i.e 470 ohm.

After this buffer amp you can use the above RF amp to drive a (100mw) linear, DBM, mixer stage etc . This is my standard buffer stage to be used in all receiver/ transmitter oscillator.

For Transmitter use:- Remember its very wide. It will amplify equally signal and harmonics. Use tuned amplifier with filter for further tx use.After this stage some sort of filtering is needed if your source is harmonics rich i.e oscillator.
buffer amplifier

How  to wind the bifiliar transformer. have a look here. Also see previous post in this blog.

(tuned amplifier and filter stage) these things I am using frequently in my design....
Small Signal Multiple Feedback Amplifier

Details at the http::/qrp.pops.net
Second amp is used in JOTA receiver by VU2DEV.

For another similar ckt after ARRL:- 2dev "The most reliable and simplest solution would be a 2N3866 multiple feedback amplifier as given in ARRL hand book! Gain is 17 dB and output is slightly more than +19 dBm as measured! Of course the resting current is high almost 63 Milli amps @13.8 volts! Multiple feed back: Emitter an unbypassed 5.6 ohms and collector to base 560 ohms feedback resistor! Base to ground is 270 ohms and emitter bypassed resistor is 18/22 ohms! Collector bifilar transformer to match 50 ohm low impedance output!   "

Tuned Amplifier with filter
 I have used this stage with my VWN transmitter with premixed oscillators, 14194 DSB exciter, Few TRF radio and more projects

(will update this with redrawn picture.
to be continued.....