Madras Disaster, december 2015

I was seeing the human tragedy at Madras(Chennai, India),due to the natures fury. Even if nature's one element increases Air, Fire, Water,Earth all becomes cause for the disaster. If we are lucky the disaster is small, but there is still loss to the humane and infrastrutcture and in long-run to economy. First thing, we wish in this situation is water, food, hygine, warmth blanket and message from our family they are ok, we are trapped here, save us. In this last thing related to the communications, as a ham we can help them a little.

I look around, am i disaster ready ? Yep, my antenna is up. i have light(electricity), what If ? my light goes out,,, for 5 hours i can use a 40 meter analogue receiver on car battery. After that nothing. sorry, i do not have transceiver...

What ? i can not afford commercial set up, not able to build one, and great ham not able to provide the pre-build air worthy transceiver. But, there are many designs, bitx, vu3gcm,rm96,nr60,vu2atn,various dc receiver,r7, gr7, jota,HF1 etc etc.... there is a gap of simple tech. We have very hi-quality tech,sofisticated, digital, software but not a simplest one.

In the early years of 60-70 our maritime mobile were able to accurately transmit the distres signal in morce ? they were right on frequency ? how did they do it.

Answere is simple 2182kc, 6725kc , 455 to 465, 500kc etc were maritime frequency. I have seen the emergency set powered by a crank shaft, CW, DSB with portable vertical antenna and they all were xtal controlled transmitter. I have seen fixed frequency receiver also to receive 2182kc the local oscillator was 2682kc xtal, IF was 500kc. So, you got two frequency receiver. Damn ! the tech is there.

Our, need of the day is small powered cw or fone transmitter with portable antenna so that atleast they are able to radiate some effective signals around say 50km from the locations and if power is there and antenna is high then full range with big linear. We should go with new tech, that is progress but at the end of the days the morce code will come handy. When power is out, there will be less QRM.

There are many xtal cheaply available i.e 14.166mhz, 14.318mhz, 7.159mhz, 3.597mhz, 1843kc, and 10.000+(4.000 / 4194 / 4433/4286) for twenty meter, 11059-4.000 for forty meter. All our problem of hams not on air can be solved. VU2FI sir, if we import some xtals in bulk from dx or specially made say 14194kc. Let us make some simple design of one to two watt transmitter, simple transistors as active device, less dependance on special ferrite, and simple receiver (DC or Superhet )with sensitive enough to work another local qrp. If person is on air, we can depend on it. our air wave will be busy and no one has the chace to grab it up. Guys, think over it. otherwize as you have seen the everage age of hams at hfi2015 was more than 45 plus. Farhan we expect & request you to help as you can think out of the box, it is out of your league or not intune with what you are doing but we seek you to help. VU2RBI, VU2FI this is answere to your quest what will help ham not to dry up.

***
I put this ideas to the indian and foreign hams. From the response/comments I can say, may be we are not realizing the potential of this old technology. May be electricity and civilization stays with us forever ... BEWARE  there will be few black days also.........
***

My one friend put this on net. I liked the content, as it is useful.

Most Chennaites and people in rest of TN have only WhatsApp connectivity, so please copy this
story and spread through Whatsapp.

As the rescue operations are underway in Chennai, the focus should now shift to how best people can ensure public health and combat the outbreak of water-borne diseases as it is often difficult to maintain hygiene during clean-up operations.
The News Minute has compiled a list of dos and don'ts based on our conversations with doctors. Most of these... are home remedies that you can execute even without power and medical supply. Spread the word and stay safe.

> Using sari as a filter can reduce the chance of cholera and the water-borne diseases. This has proved to be an effective method of filtration in flood-ravaged countries like Bangladesh, with researchers from the US establishing. While boiling water and then filtering it would be more effective but in cases where people have no access to gas or heating mechanisms, filtering water using the folds of a sari is better than no filtration at all.

> If you have no access to drinking water, collect rain water in containers placed on your terrace. This can then be boiled and filtered for use.

> Do not stand in stagnant water. With sewage water getting mixed with all water sources, standing in these stagnant pools can lead to leptospirosis.

> If your food stock is running low at home, take a litre of boiled water and add 5-6 spoons of sugar and 1 spoon of salt. Drinking this at regular intervals will help in keeping the hydration levels high.

> In areas where the water is knee-deep, add bleaching powder or salt to it. It works as an effective disinfectant and also prevent bacterial diseases from getting transmitted.

> For those with access to medicines, stock up on ORS packets to prevent diarrhoea and antiemetic drugs to prevent vomiting.

> Have freshly cooked food that's been heated to boiling point. For those with power, avoid refrigerated food to the maximum extent possible
***
It seems our senior ham VU2FI had set-up a emergency communication room at Banglore and handled 3000 messages and helped in disaster relief in 4 days. Hats off to those hams. Freq was 7070kc, and ecolink , VHF etc were used. Hope to hear and learn from their experience for disaster preparations.
***
It seems the SIARS-Chennai , also have its own view. Will collate it after they speak it loud.
***
Personally I have no bias, I welcome all the voices pro-con and others. Life is multi-dimensional, if we have different views, viewpoints then better we understand the situation.

 IMHO we need hams who can interface with giant multi head  government on whom we depend for our joy. There are who really wants to work in field and shy away from all limelight. There are those who comes on air, there are those who just  tinkers.

It is a very expensive hobby. I have seen many persons who also developed other hobbies, numismatics, photo, tracking, mountaineering etc and survived the harshness of ham hobby.

So, ultimate aim should be enjoyment. Whichever way you find joy enjoy it.

RF Indicator

Indication of the RF has a very important role in transmitters. I saw this ckt on farhan's blog. It is a very clever and clear use of the simple diode detector. I was using the peak detector for Rf indications etc but this is a good one. Its simple, it works ,

 

please not :- it does not accurately measure or measure anything at all, it just indicates the RF level. When there is voice peaks, it flickers in sympathy with the voice.

 

For CW the presence of RF is easy task but for voice modulation its difficult. For my xtal controlled CW/DSB tx I use small homemade receivers but nearby receivers is being overloaded by the transmitters and we should not use our sensistive receiver during transmission. Its front end will be damanged....

 

Put it on the final linear amp.at the output. Ckt is self explained. Change the R according to the power level of the amp. Please don't use the preset or variable resistor, that might break disturb the Rf network.. he he..

 

For R try quarter watt carbon resistor, 10k to 4k7.... enjoy the flicker. Functionally similar was used in VWN- Tx but that was in DC current path.

 

In my experiments, I had used two linear amplifiers. One 2watt for driving my big 20watt linear. I did put this indicator on small 2watt linear.  At one point in RF when i increased RF level, there was constant light on LED, that means the High local stray filed from big amp was coupling and driving the LED. So I should have put the RF amp in small boxes and also put the this indicator on big amp....so keep this in mind when you are using two amplifier and two indicators shows the different dances... he he anyway it works.....

 

Wheel is here Enjoy.

On air , part-5

Tale of two transceivers:-

I have promise of the SSB transceivers on 20 meter an another on 40 meter. I have all types of wire antennas, dipoles etc, power supply for QRP and one or two liners.

Licence is valid for next years.  And upto next year will be in and around at my present QTH. After that it's possible I will not operate, not renew my license ! Who knows.....

I have plan to print the QSL CARDS. Will send it for one months QSO. Then 100% on demand only. Will be regular on band and will finish up my bitx and other transceivers and will gift them. Will print card without call sign so other friends SWL can also use it.

If this does not realise or there is some problem, then what ? Nothing. My region, district is a ham desert. There is no one around me. I have know how to teach. I can initiate/encourage some new guys into becoming hams. For that, I require a working Transceiver  to give demo. I could not give them the feel of being on air with a sinleband xtal CW TRX.

As a seed some trx was needed, I have nothing to test my home brew stuff. Loss of digital marine receiver was serious loss. It's not just money, I lost a friend also. I dislike loosing the friendship, for me friendship is more important , as its hard commodity to get by easily.

May be I will be getting the JOTA transceiver 40 meter and BITX-20.

Enjoy,
73
De VU3INJ
INDRAJIT,

Wheel has moved.....

Ha Ha Ha ........ where is the wheel ?

As of 15 july :-
May be in this week I will be getting this JOTA transceiver at my shack... But, somehow my desire to be on air has been killed by "build the bitx dialogue by many senior/juniour hams...".  But, for me this is it. I am not buying any HF transceiver after I receive above Jota Trx and BITX transceiver.....

23 July 2015:-
I have received the Jota transceiver. Its modulations is nice. vu2dev has specifically made for me. And for making it he made another rig also to test this rig. The metal body is good. VFO is quite stable. Very kind of 2dev. He has gifted the mic-handset of ahuja make. Also, did not charge any curier. Thank you Dev Ramaprabhu sir. 

25 July 2015:-  
I did test with long wire and power meter. It seems its a real QRP of 2watt. Today bought the 12 volt relays each costing rs70/- (about 1 dollar).  I asked the shopkeeper give me 8 terminal relays. He  smiled at hearing this. I should have said, give me two c/o relay. We are in this business since last 15 years.... he he. Ya, i said, this is the layman's language..... 

I am not using the existing 20 meter PA by output changing LPF coils, I will make another 40 meter Linear  based on IRF840. Let's  make and see that it gives me the contacts. With long wire antenna i was able to listen only. Will erect the dipole tomorrow. If  this set-up does not give me anything then i am QRT and will be running the beacons only ( pirate)  or CW on xtal based transceiver.

Peoples using smallest efforts, little money and easily come on air. What is problem with me ? Spending this much time , effort, resources, still not able to put myself on SSB fone. Many peoples have helped me. Still this problem ! VU2KD, VU2DEV, VU2UPX VU2PTR, with pcb, materials, instruments, books, tech support. They are the masters of the masters.
May be my ham-karma is bad. and frankly I don't know how to balance it !!!!!

I have no local support. My support is from DX places. Time and time, again its proved that the QRP never works for me. I need atleast 15watt to 20watt pure RF power, just to be heard at some nearby stations.

26july 2015:-
Opened up the JOTA TRX top lead. A very professional approach. The metal body is a very strong one. May be 16 SWG sheet metal. Which can be very hard to bend. Inside there is big relay. There is one copper plane in middle. Which shields the VFO as well as the modulator. The PIC counter is neatly placed behind the LCD panel so it does not occupy too much space.  It smells fresh. No smell of anything burning. There is no loose connections. Everything seems to be in order. But the 13watt linear is not producing the power ? I have run CW tx in those its a continuous power, in the SSB its peak power.  OK ? OM Sunil  TT also has the similar trx, but he has dds vfo. May be there is no problem at all. I just need to put a big antenna and a very big linear due to my living in the dry western part..... ok
***
27 july 2015:-
I opened the top lead and staring at the linear. Trying to figure out the connections. I am tired of the "miss murphy". Requested for the ckt diagram. If possible will start trouble shooting. Most probably I will remove that linear card and put  my own "2watt linear" into the box.

I wished that VU2OO had gifted me that RM96, which he promised three years ago. Anyway sometimes you have to let it go.....

I AM NOT ON AIR-40 METER as of 28july2015.

there is no wheel !  the wheel has not moved. End of searching the wheel.

ENJOY
(Each time I say I am QRT and still try to mess with Miss Murphy, hope one day she will yield to me and she will give birth to the child called success ! )

On air, part-3

This is my third part for being on air. 

I had tx, I had rx. I was having problem in the QSK.  I was literally furious as I had spent lots of good money over the junks. From few good hams I bought secondhand  equipment's, and to reduce their own burden, those good man passed the buck and it stopped with me.....

I saw my own homebrew-junk-box. I was seeing that I had all types of modules. Be it modulators, demodulators, IF amp.TX amp, Linears, Power supply, Diodes mixer etc but no DDS VFO. I was finding it very hard to make it work. I am not digital-man, I am just a disecret tinkerer. Then I has realizations and I started boxing the things.

So excused myself from the  Indian Homebrewers facebook group. I was angry. I had the valid reasons. Only because you fill up some etchy-bitchy pcb with success does not mean the end of worlds. There are many things in RF world.

I dedicated my two -three days in perfecting and boxing the existing system.

I made two 20 meter antennas. Put the qsk in DC receivers and Superhet receiver. Will further improve it with tr-switching. This time the slow tuning and qsk ckt worked the miracles.

Then started the test. Many peoples helped me, coaxed me to make the dds vfo, I said the dds vfo will wait. Let me finish first what I make perefectly. And the test come ok.

Even with 2.5 to 3swr and 15 to 25watt I was able to put the signal through the south india. Then was also able to receive the control signal in my receiver. The receivers need fine tuning. Otherwise its all operational. Now final little glitches needs to be removed and it will successfully give the scheduled contacts. Sked. 14314kc.

Will upgrade to high power and dsb...

I have to thank one person for helping me out in air test, listening to me, checking with me regarding the progress...... thank you........... de vu3ink....

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.


Thanks.

 

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.

QUADRUPLER MODULE

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....

08feb2015

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...)

09feb2015

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.....)

THE WHEEL HAS BEEN RE-INVENTED use it as given.

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




 

CW TX 14316kc

RF Linear

Last year made a CW transmitter. Power was very low. So decided to make a linear, then  after a year my cw tx is perfectly working with this  homebrew linear.

Here is the picture.

All details will updated later on. Atleast this is working......( updated as on 27jan)

Main power supply is the 24-0-24 @5amp with 0-12 @1amp . The cheap computer fan is used to cool it. The bottom plat is a thick metal one. Used as a heat sink.

One 12v dc @1amp, white box is used to supply the power to swr meter and keyer. Here the SWR meter requires the reverse polarity power supply.


The open box is exciter with having its own power supply on right had extreme. Well I can drive the exciter from the main transformers... will do that.... one friend said this much power sources.... well its on the assembly bench so I took liberty of using more....

Here is the ckt diagram.





linear amp after modification



(with input 50ohm resistor exciter can not drive amp
so removed the resisotors )

The RF Power Amp is used to drive the inv-v dipole antenna. Antenna is on the roof top....


Inverted-V antenna

On first test, i tried to load the dipole only 12feet from ground. But could not get the report. Well on suggestions, I made another antenna on the top of building. It was not cut to exact freq. Bought 20swg copper wire. 100 gram at rs.60/-. ... Used common dish wire to connect with TX. The plastic tube used as end insulator. Antenna was done in clear hurry..... but it worked well....

Used 20watt RF power. The SWR meter shows me the 3.0 reading. Then 2DEV gave me hint to put the antenna away from rooftop about 10feet with some plastic pole. I used a bamboo. then SWR reduced to 2.6 ok. One important thing I learned that for the receiving you can put dipole anywhere but for transmitting you must put your dipole/inv-v ver high and without any obstructions ( metal building) tree might be not that much trouble....  Put antenna atleast 30feet and up and you can punch a hole with 20watt north to south. For 5watt I got about 55 report. for 20watt about 57 report.

On my request 2KD also suggested few things. Well as the rooftop renovation work is going on will assemble/modify the antenna next week and try to have cw/dsb toway contact.

My test signals could be heard all Gujarat, sought india. But, the central india and Northern india I could not get the report....

What I feel:::   In the secondary school you get your first kiss..... (its different matter I have never got a kiss).

But atlast I have become the transmitting ham. Will modify it to DSB and hook up a receiver.

There are many hams to thanks. They helped me in varous stages of deveoplement by moral supprts, pcb, guidance, critical reports, critical words and above all kept my company....... 2TOO,2KD,2DEV,2UPX, 2PTR,3YFD,OM Ashok khachar, OM Vagishetty, Om Gurudata, 3HMM,3HML,3JOJ,3JOG, Om Mehta- Jamnagar, ( Last year during cwtx exciter time 2RAK, 2ATN,2UUU & 2ESE,3SXT,3SXN,2ORO....) also land lots more..... THANKS.....

20 meter transmitter

The QRP transmitter.

 I was seeing through my old copy of the EFY. Found this. In year 96-y2k, Pradeep.G,   D.Prabhakaran,    vu3nsh etc had published very good work.

I have not made this. But made two tx on 80 meter using little different design and they had worked. All parts are easily available and can be substituted with others. It is a very straight forward transmitter.

If transistor SL100 is not available try 2n2219. Use crown heatsink.

Instead of BD139 try C1162 transistors with heatsink. Any metal slab with 5 cm by 5cm and 2 to 5mm thickness should work. Or try any heatsink you have. You can also try to use the cabinet chasis as heatsink but do care to use the mica washer (but dont use this last option). If you are feeling that transistor is making too much heat try a small fan, computer fan. Now a days computer fans cost very less !. Put it above the heatsink directly throwing air on it. fasten the fan tightly so it dont wobble the chasis or the ckt. Do, power the fan seperately as it requires 210ma ,12v dc.

Seperation of PA and other stage is not marked by dotten line, but i suggest to make the PA in different board, if using the general purpose pcb . Please also enclose the oscillator stage in a small aluminium box for xtra stabilty.

Minimum component and QRP does not mean we dont give it a big box. Of course ! cost will increase, but the metal box enhances the quality of your projects. In the end you will like the result.

May be we can switch the oscillator and buffer stage by a transistor switch. Try SK100, BD140 OR 2n3054 (?)  or a relay if its chattering is not annoying to you.

I see one further developement that we can modulelate the pa stage to make AM Transmitter for local use. It is worth a try.

JF01 ? getting old so forgetting his name also made three transistor 40 meter transmitter. Xtal is important. We will find this 14.318 xtal for some more years. its very cheap 10/-rs per piece. Dont try to port it for other band, you will end up frustrated. Use it as it is.

If i make then, will be sure to upload with my own version. But one last tip. Try one stage at a time. First make oscillator, then make the second stage use it. tweak it. box it. now make the cabinet put everything, fan etc and make the thrid stage. Some sort of atu and relay to switch ON off and QSK is needed. If some seniour hams with antenna analyzer makes some antenna then it will be our standard rig for lots of hams. By, the way 14.318kc xtal freq is very less populated so THE QRP ham can survive there. thanks enjoy de vu3inj

06april2014
please search the jf10zl.html and you will get lots of information regarding homebrew project using simple transistors and they work nice.

14318kc cw transmitter

 This is my hand drawing.

 This is how i put fan on the box , above the power transistor.

For the AM Modifications please search the pirate radio transmitter, they have excellent modulations method i.e heising modulations. Here a choke is used. Now a days there is no audio choke available, best ways is to wind yourself or order speciallly to local transformer manufecturer. You have to provide the data.

Another method is to use 12-0-12, 1Amp power transformers secondary. It work. There you will also need an audio amplifier.

I hope to make this one for  am local use .

In this project please look the blog from time to time. I will not disappoint you FRIENDS.....

14.318 Mhz. CW, 20 meter transmitter

14318kc transmitter:-



bitx version-1 (by vu2ese) linear

This is a 20 meter transmitter brewing up after long 10 years of absence in homebrew. So, the technique is of old faithful transistors ( he he ! in the age of digital the transistors are also old tech !)

Here cheaply available (rs.15) fundamental Xtal is used. 14.318 Mhz which falls on the one end of the ham band. But, generally hams does not go that much high up ! so, with this tx sked is needed. And one possible benefit will be there will be less QRM of QRO rigs. around 14.200kc band is crowded.

1. First board:- Xtal osc with buffer. This ckt is standard. Here 1k pot is used to control the RF going into the RF amp chain.

2. Second Board:- This is the single stage tuned amp. I have used the BF494 but any c series transistor can be used. If it does not work nice will change it to 2n2222 in metal pack. Here, old alladin former is used as tank of tuned amp. This is 10 years old legacy.

3. This board consist of driver amp based on 2n2218 and RF power amp based on IRF510. This is very straight and standard amplifier. Heat sink is must for IRF.  Output filter is not designed at present. Once it heats up dummy load filter will be made and connected to the dipole. I am expecting power of about 5w.

CW TX

Only part tested is upto driver amp. I am thinking of making the RF power stage on the basis of VU2ESE, OM farhans bitx20 v1 (first version using the tap-washer !)  i.e air core transformer. But, vu2*** informs about different version of this output transformer . So, will try his suggestions also. And see which thing works for me. Only thing important is working ckt. I am ready to borrow from any idea, but it must work me.

NB:-At present (nov2013) this project is not complete. I want to power finale amp from 18vdc to increase power,so it will need few more changes.  ( I did power up with 24volt  got around 3-4watt, disliked using  two different voltages for single transmitter thus ended up using 12volt and 2watt ok.)

As of 28 Jan 2015 I did not drive the exciter with 18/24 on the final irf510 instead accepted whatever power it produced with 12vdc and drive it to external linear. This big linear produces around 20watt and punching whole indian continents.

Will upload the finished fotos. soon....

As of 14 feb 2015 made replica of this transmitter. It works. People are making the transmitters for this freq. It will become popular one day. de vu3inj, indrajitsinh.

WHEEL HAS BEEN RE-INVENTED, USE IT