Wednesday, December 31, 2014

BITX Making part-0

Last year, during our brief one minute meeting VU2UPX gave me one packet. This packate contained a good selection of the PCB,PIC for DDS VFO, DVD.  I am thankful to Om Charudatt -ji for  this gift. He had specially commercially ordered those pcb.  Whatever my karmic problem, I was not able to assemble the DDS VFO ( see the previous post ). This costed me a years homebrewing time. Really appreciate and make further projects. Most of project were dependent on the DDS_VFO. I gave it a second chance.  Lastly from that package I made the R7 receiver successfully. ( see preious post)

Due to work, could not visit the HAMFEST INDIA 2014 at Banglore. They gave one BITX40 PCB to all the delegates. and there was arrangement for low cost kit components for Rs.500/-.

Well, I missed that bandwagon. I was felling little desperate. So requested for spare pcb In the HOMEBREW forum. Few promised, but arrived none. (piece be on them atleast they promised). . I wanted to brag about this bitx.  Seeing this, my neighbor and senior ham VU2BGH, Om Bhogibhai sent me his pcb.  Few days later , as a good gesture for participating in homebrew project in the HOMEBREW FORUM, Om Shinos sent me one PCB( also to 6 other friends).

Thus I got two BITX40 pcb , so I remarked that...
Now my time for bitx making has came.... all the bragging will be on vu3inj.blogspot...... pls bear with me.....  My friend @2UPX remarked the following to me.........all the best, but you already have your hands full, Oh humble peasant. He was right but I replied that, you know that commons and kings, never satisfied with their greed.... to make new things.., to acquire more things......to get more beautiess.... he he he.... but actually i never had the cance to make the bitx & brag.......before bitx actually i wanted to make ararinha and one dsb tx......
 
This is the beginning part, all the bragging and other thing will be from the bitx40 making part-1
I will stat wit the pcb, components lists, links..... I am not giving any time frame..... I might need few 10mhz xtals and cores from some vendor....

so work in progress..... 2015...............

Friday, December 26, 2014

XOR gate mixer, vu2dev

The XOR gate pre-mixed oscillator mixer,
There are many mixer available for radio amateurs RF work i.e common diode mixers, transistor, IC, DBM, some specialized IC, they have their own advantage and dis-advantage. Sometimes you just need a single frequency devied out of two crystals...... a pre-mixed oscillator...                 
 
VU2DEV, (Dev Rama Prabhu) recently published this circuit by taming the nasty little XOR gates. He reasoned that PLL has xor gate why not try it as a mixer. He made it. I likes so requested for the circuit diagram. After two days, provided me a handdrawn schematic with a remark that he wanted to test it at least 2 - 3 times, so its repeatability, consistent results, characteristics can be predicted. (26dec2014)

 














 
Here on veroboard has two IC sockets. He tried it with two different set of xtals before giving me the ckt to test the repeatability. Only one IC is used for one mixer. LM7805 is used for voltage regulations. (A must.)
 
We need to put a tuned amplifier to filter out the  harmonics and unwanted spurious frequency products. Remember it is still a digital ckt (squar waves reach with harmonics). @2dev has put a LC tuned class-a amplifier. Not shown in the ckt diagram. See the second picture, the transistor Amplifier is on the copper plane.
 
My friend Om Jishnu has also made this ckt with success. I have to try this out. This digital gates will save me from ,using the hard to find little obselotte TA7358 mixer ic. see my previous post on this ta7358 mixer. They are good, but if you can do more with less component, in a simple way, why not give it a try... You will sure to love the result. Build process and other data will be updated later on....
 
When time permits, build it & update my own pictures giving my own twist...... till then ENJOY ( the wheel is running ,re-invented by 2dev)

7159kc beacon cw-tx

                This is my QRP project which was developed within a minute. This project can be made within an hour. During the testing of the R7 receiver needed on air signal. I did not wanted to test receiver with bench oscillators. 


7,159kc beacon/ cw transmitter, (40 meter band)


Bifiliar transformer wound on the ferrite balun core is a non critical but a very essential part. You can use any other toroid. Use 30swg, enameled copper wire . Give 8 twist per inch with small hand drill or by hand.( don't use power drill).

Had bunch of the BC549c. It is important to use this transistor, particularly c variety. It is also okey to use BC547/BC548 etc but all the c variety has high gain so can be used for 10 meter and have litte more umphhhhh.

First made the collpit oscillator. don't forget to ground the xtals metal case with wire. Sturdy mechanical fabrication is a must. I made it on the Veroboard.  ( will upload the picture). DC input to Q2  is about 180 milli watt. By putting two extra stage of a small linear the power output can reach to comfortable 500mw to 5 watt.

Well box it and use it as a small beacon around my QTH for testing the on air signals.

I had another idea, put a direct conversion receiver strip, shown elsewhere on this blog to make a simple qrp transceiver.

It will be a really big challenge to get a few contacts with this......

Saturday, December 13, 2014

HF SSB RX, VU2UPX

During the eyeballs visit with vu2upx had gifted me one SSB RX pcb along with other pcb and DDS VFO board , IC.

It seems to be R7 receiver. It is the simplest ssb receiver. I have plenty of the ta7358, 10mhz xtals and tools. Why I did not noticed it earlier. Anyway lets catch up with true things.....
here is the pcb & ckt diagram

Top side view the board::-




Componet side










r7



Showing the links of the R7
*****
The circuit diagram for the above pcb. The PCB is courtesy  OM Charudatt, VU2UPX. Thanks boss

Only components I don't have is the bf245. May be I will use 2n3819 which is on hand. For the varactor have to think or do some  juggad....instead of MV2109 I have BB139. Another bottle neck is the can used in oscillator and filter. I have plenty but not this one. need to modify it. All other parts are simple and one weekends project.

On the 13 dec started this project. lets hope I finish it and brag about it........
on 14-12-2014 done all the big parts i.e ICsockets, I cut 18 pin DIL ic-socket into half and got two 9pin SIL, On the rough edge, please file gently to make it smooth. As this sunday writing down the parts list to shop.
here is the list with my note. Click it on to make big.















1.Print the ckts. Study the ckt and pcb. See that you have all the necessary critical components. There is also help in the form of three pdf files at the fuji qrp website. Read it please. If possible characterize the filters, make LC tuned tanks before doing anything. These are the hardest element of this kit.

2.Ask the elmers, original builder or someone who built it for some insight. In every design there is always some silent points which needs to be adhered. My dear friend 2upx who gave me this pcb remined me to start from the back. Thats the way we all do ! Frankly this will be my first "RF KIT" build. I have always done my own design on perf boards, copper boards with giving some twist to the originals.

3. Study it again. see that you have all the tools instruments. Mulitmeter, 12vdc power supply, cutter, twizer,LC meter. See that y our soldering iron is very clean, if using ordinary iron then file it shining. As tracks are very close there is possibility of accidental shorting. Use MAGINFYING LENSE to do visual inspection. Before placing the components see that you are placing the right values, measure /check it( with mutlimeter, LC meter etc ). Once the components are soldered there is no way to know what it was and the trouble shooting will be very hard.

Lets begin solderig.

4.I first soldered the IC sockets, connectors. As a good practice you should use sockets , connectors.

5. Then Soldered the power supply module. LM7805, 1N4007, LED indicator.due to 1000mfd there should be good filtering. Important for smooth audio.

6. Then the audio stage. LM386. Mounted all the components. I wonder why there is no by pass capacitor (0.01mfd) at the intput pin3. Anyway i am not doing my own change. Try to stick to its original values. As it is the superhet design audio stage is not critical but it seems to have low gain.

Connect the Volume pot and 12v dc. Don't forget to put LS. See that there is voltage on pin6 of LM386. LED light is ON. Normally there should be only murmur/slight noice in speaker, But it should be not loud one. otherwise halt and investigate. Now do the finger touch test. There should be loud noise. All well, then proceed to TA7358stage.

(Gain is distributed all over the receiver. Still i feel that AF preamp for LM386 is needed.. I had to remove the 1k restor between pin1 and 8 of the LM386 to increase audio.)

7.When we do something in india we have to idianize it. in europe & america there are many local hams with strong signals. I dont have hams around me in 100km straight. So i have to make it more sensitive and need not worry for local strong signal.

8. At this time i had to choose the IF frequency. I had 10 pieces of the 5Mhz xtals and 10 pices of the half size 11.059 Mhz xtals. For matching the xtal i built a small oscillator. See the " filter making 1.html ". Noted the readings. Asked the seniour OM over internet for choosing the 4 xtals and one oscilator xtal. They unanimously chose. I put those xtals.

9. BFO was moving from 4999.8 to 5001.8 kc. Okey. At this time i should measure the bandwidth to put the BFO at right frequency. But, still i went on. This stage passed the finger touch test. Moved to the Front end mixer.

10. I just got the 4 pieces of the 680 pf of white styroflex variety. These are good for making a a very stable VFO. Used here. I could not find the 4.7micro henry coils for pin3 load. Can find only 100 micro henry and 3.9 micro henry. Got them. resontaed 3.9 micro henry with a capacitor in my LC Test Oscillator. with 68pf this coils resontates at the 6.9 mhz. I did not like a non-moving resonant tank , will replace it with 100 micro henry coil.

11. Went again to shop to purchase the few more henry coils and few pf values. Found the some old IFT like coils. Wound one IF with one turn. It showed teh 0.1 micro henry. So 11 turns were wound on the internal dumbell and it should be 1 micro henry. As was pushing it into the pcb for knowing whether it can fit or not. The pcb holes were very tight. So with small hard nail tried to winden it. But, still it stuck. As these coils very very old one leg broken during pushing & pulling. I said this will create a mesh. So, soldered it anyway and resonated to HF. it gave me about 22pf+68pf at around 12 mhz. Okey with me. With a varactor i can tune it. for entire 40 mete band. For the varactor i could not find the MV2109. I have BB139 but will try 33v zener diode or normal 1N4007 rectifier diode.

12. till now the luck was favouring me. I have spent atleast 1 hours per day for this little project and at the finale it is giving me trouble....

13. Need a resonant ckt at the front ends. Will have to wind the IFTs for 7 Mhz resonance. I don't have the BF245 FET. Well i can substitue the 2n3819 which is on hand Its not critical but it should be a FAT so that the tapping of the coils can be avoided. This stage is a must othewise the gain will suffer. All the RF selectivity is here. Hope gain of this stage migh make the receiver roarding.

14. I will Tune it with some xtal oscilator (7.159Mhz) and then conect antena & on air test. Hope i get the on air signals.

( Work in Progress...so will be rewriting this soon24 DEC 2014)


xtal filter making 2

Crystal filter making :- Part Two

In the first part we explored the theoretical part of the filter. Now, at this time we will actually try to find the suitable xtals for the bitx transceivers. Then try to measure the  bandwidth, frequencies of the xtal so that we can put the BFO accordingly.

First thing :- The oscillators to measure the series frequencies...


xtal series frequency test oscillator
*************************************************************************

As discussed on the part -1, measured the xtals series frequency with & without 33pf. All the data is given below.

I used the PIC frequency meter. all readings are in Khz. the minimum reading is 10hz if you get more accurate reading it will be better to use it. All  xtals are standard HC49.

{ Please be aware  11059kc halfsize xtals did not oscillated in this ckt ....No.8 is not the typo it was actually 10mhz mixed-up in the 5mhz bag. }

(wire open-with 33pf,)  ( wire close-direct , shorted the 33p)

xtal no.--- Open---- --------Close

1.        4999.38       4998.39

2.       4999.37       4998.38

3.       4999.38       4998.41

4.       4999.39       4998.46

5.       4999.36       4998.36

6.       4999.34       4998.33

7.       4999.33      4998.35

8.        ---------      --------

9.       4999.36      4998.34

10.     4999.40      4998.40

11.     4999.37      4998.37

Now, what 3 or 4 xtals should i choose for 5mhz ladder filter. ?


(1,2,5,7,11 would be my selection dear Rathorejee! replied VU2DEV and all concluded on 1257 for filte and 4 for oscillator)

filter from the  xtal no.........1,2,5,7
and for oscillator use the xtal no.,,,,,,4

In the selection we have to see that the xtal frequency should not deviate from each other about 50hz.

THUS this part concludes with success.........
****************************************************************
The xtal filter as brewed :: How to test it.How to describe a filter ?Measuring other parameters. i.e Xtal activities, frequency will write on these later on...pls..... meanwhile........
****************************************************************
One friend popped up the question "what shoud be the position of bfo freq. if the IF is 4 MHz and VFO is 11 MHz... to tune 40m LSB... should the BFO be below ladder filter central freq. or above the ladder filter freq. ..." .. i checked your blog first.. ... din found the topic... so can you brefly let me know...
Interesting question actually i made a little write up and forgot to upload here. Well answere is simple but somewhat lengthy.... consisting three parts.

First part::- consider filter as a gate. This gate has a centre frequency, actually a band of frequency between those frequency it allows to pass and for others there is steep rejection. These frequecies can be measured by feeding it a RF Signal from DDS_VFO and measuring the voltage at the output. At some freq it peaks then at some freq it drops down. now is the interestng part we have to find this steepness. at one point filter has 3db bandwidth these are two important frequency. It can be represented by the Voltage (y-axis) -----> Frequency(x-axis)... a flat dumpbell shape.

Every xtal-filter has different characteristics as it is not a commercially made filter for a fixed frequency. In our homemade ladder filter we accept whatever frequency band-pass our filter gives. so each fitler differes from other homemade filter.Bandwidh can be increased / decreased by ckt topology and components emperically.

Second part:: - Amplitude Modulation is the basis for all the analogue modulations. In the Amplitude modulations there is carriers and two sideband containing acutal informations. (about 66% rf power is at useless carrer. In the DSB signal we suppressed teh carrier by balanced modulations. Now our signal contains only informations in two sideband. But by using the DSB singal we still waste our RF power in another sideband. As both sideband contains same informations. Is there any way to remove this another side band. Well we have to trim the sideband by some filtering. And here the role of the filter comes.

In DSB modulations ,now our information is on the two side bands. USB is the signal where the information is on upper side band. in the LSB the information is In the lower side band. Another concept clerance this side band is related to the carriers frequency.


where should the bfo need to be put..... Now, there is steep dumpbell like shape of the filter and the dsb signal is without the carrier unlike the AM signal. We have to play with it.

Now, we have the steep ness of the filter. Our signal with two side bands. We have to fix the signals carrier frequency so that it collides with its steepness and let pass only the single side band of our choice out of two side bands.

Third part::-
For LSB The carrier frequency should be high i.e high side of the filter steepness

For USB the carrier should collide with lower side of carrier steepness that is its frrequency should be lower.

To lower the oscilattor frequency use the choke and to increase the xtal osc freuq use the capacitor. Well using the LC in xtal oscillator will give you good tuning range, as we don't know where our filters freuqncy is exactly ? Xtal filters generally shift little down from their xtals marked frequency. To shift the freq down we need L in osc.

hope you got it. some time i also get confused, so i draw it on the paper.... will upload it with full diagrams Actually these all are the practical things once you understand the theory afterwards it has be done practically.



graphical presentation of AM signal & xtal filter
 


After passing through filter we got LSB signal


After passing through filter we got USB signal
























Query and answere ends here.

Chat Conversation End

It will be ALSO interesting to read the PY2OHH. he has published god work on farhans BITX. I HAVE FOLLOWED THE 2ESE in xtal making. As many people have successfully made xtal filter following him. Why re-invent the wheel ? Lets use it, as invented by the VU2ESE.

(work in progress ,,,, )

 

Tuesday, December 9, 2014

xtal filter making 1

Little History:::

This is the one of the building block which was never mastered to brag about. Years ago I hade made one xtal filter, without any matching and see the way I put the pcb, aluminum shield. After a decade I look and smile at it. It was never used, just soldered it.

After the free gift of BITX40 PCB & cheap/low cost kit supply at the HFI2014 many peoples are making the BITX. from the facebook group it seems that VU3JOJ and VU2SWX are making and uploading the process/fotos on facebook. Few others were also making the bitx.  (As I did not attend HFI2014 at hydrabad, so I did not get the kit or free pcb) I requested for the a gift of pcb if any other ham have spare or not building it. But this gift  did not arrive as of  9dec2014(!) , Then asked a friendly person to make one pcb, not coming. then asked another friend to make one ( which he will at his leisure), meanwhile someone suggested to make Dual bander for coming onto the air.  Asked the kit supplier of HFI2014 but peoples were not giving good opinions. What I can say about it. But if you are reading and want a kit then buy from the VU2SUA. Only he gives the matched xtals.


Whether I make the bitx is not sure but mastering the filter is a must to make my many dc receiver into superhet and DSB TX into the fullfledged SSB transmitters. Lets see.


Designing the Xtal filter :: ( little theory first)
Page-1


source:- www.phonestack.com/farhan/xcvr1.html.
bitx smd version crystal filter testing.html
bitx.htm by py2ohh
TT's Jotting Blog of VU2SWX ... Building Bitx Part2-The crystal filter. html

Page-2





































First stag is choosing the IF of the receiver. The BFO should not be harmonically related to input RF freq,  for 14mhz band 10 MHz IF is okey. so VFO becomes 4.000mhz and IF is far from one and half of the vfo.

Second stage is you need many xtals so it must be easily available. Higher the frequency greater the VXO shift. Generally Ladder filter does its work (filtering) little lower than xtal marked freuqency.

Third stage is matching its frequencies and make the ladder filter. This musing ends here.

Fourth stage is measuring the bandwidth and other parameters of the xtals. For this I don't have any access to instruments i.e. CRO, RF mili voltmeter , DDS VFO, Compute programs
links are on the scanned page please read it .....

Please see part two for practical selection procedure for crystal and other details
****

 

Monday, December 8, 2014

RF-AMP designing problems


On the Indian Homebrewers facebook groups posted this Indrajit Sinh
I want to try this ckt, as it does not need toroids. hope simple balun cores will work. i have 36volts power supply ready. dsb,cw tx produces about 2-4 watts. From your view points am i missing anything ? or suggestions please. ckt is on workbench.....thanks.
I want to try this ckt, as it does not need toroids. hope simple balun cores will work. i have 36volts power supply ready. dsb,cw tx produces about 2-4 watts. From your view points am i missing anything ? or suggestions please. ckt is on workbench.... I NEED MORE THAN 20watt.thanks.



    PLEASE NOTE THAT ABOVE CKT DOES NOT WORK.

  • I also added that how much power should i expect ? i have big heatsink with fan. what will be tune up proceedure of gang capacitor. this is rough sketch, yellow lines shows my intended modifications. i am soldering it. Not finished yet,...

    Ashhar Farhan the output circuit is a series trap connected to the ground! thats a terrible thing to do (it passes the rf to ground at the operating frequency! i would suggest that you could use a tv balun or even an tap washer. this will also need a low pass filter in the output. it not only clears the output harmonics, it absorbs the stray capacitances of the bifilar output transformer.

    Indrajit Sinh Thanks Ashhar Farhan May be i will try put PI or LC filter. Yes, sir tap washer i have tried in 5watt amplifier. It works. due to 30 swg wire it becomes very hot. This time i wanted the more than 20watt and did not know whether tap washer will work at these power level !

    Dev Rama Prabhu Rathorejee, there is one QRP boots circuit in your Handbook which also does not need Toroid's! By replacing his RF transistor with IRF510 we can easily get up to 35 watts with 24 volts supply, except that it is only 40 MTR band! I have tried that circuit and shall post a foto tomorrow! Need to take care of capacitors, higher voltage better!

    Indrajit Sinh I am amazed at the whealth of much needed information available with this group. Thanks VU2DEV sir, looking for it. 40 meter is also okey. I need something consistent which when fired give me an assured contact with friends.


    Nidhi Rajeeve Buying some good toroids and following standard proven circuits will avoid wastage of time and money. Moreover proven circuits will work like a charm. Its high time,that we should junk PVC gang caps and go for reproducible home-brewing.

    Aravind Balasubramanian This is where kits make life easy Try joining the Siars Chennai VUSDR Kit group assembly which also has seperate PA board with Lowpass filters covering all the HF bands

    Indrajit Sinh Aravind Balasubramanian digital is out of reach for me. This is my desperate attempt to get a few cw/ssb/dsb contacts before i once again go QRT. It seems there are very few peoples, who build make RF PA.
    3 hrs · Like · 1

  • Indrajit Sinh Nidhi Rajeeve, i dont have any fobia or toroid fobia or dislike for digital, as simple brewer i want something which can be reproduced by anyone. I make and if it does not work then tell the crital report in a clear impartial words.... may be what i do is a re-produceable one . is it not so ? TAHIR we have see the path of signal , from where RF is coming and where RF is going. FARHANS comment is right. At the series LC the impedance will be minimum and rf will follow the minimum losss path i.e ground instead of going to hi-z the antenna connected at the tap. In the filter rf is experiencing the impedance and only way out easily is the antenna. So , i doubt there is little drawing mistake or 2vkc might have modified but not cared publish it. To put end to our discussion only the 2vks or 3nsh can correct our doubts. Thanks to all. PY2OHH, ararinha, first version has the solutions. It used the simple coil for impedance transformations. Once again thanks all. de vu3inj.

    Ron Mallik This will not work: the output is a grounded series resonant network! RFC from drain to Vdd and then a l or gamma network, followed by a 5 pole lpf, can be managed with air core coils on discarded white board marker pens as former. In your case: load impedance is higher than drain output impedance..so use netowrk 3 or 5...or whatever: here: http://home.sandiego.edu/.../e194.../jwmatcher/matcher2.html


  • Ron Mallik Use Drain impedance as Z0 = Vdd square / 2 Po....ignore drain capacitance for now....
  •  Finally this ckt was found to work for me....
  •  
    
    RF Linear
     
    here it is ...... writeup is on next blogpost.

RF PRE-AMP


For the 40 meter, 20 meter what type of rf pre-amp stage should be used. ,,,,

any design guidelines, examples , i have made one but i need some practical insight please..... it will be driven to the diode pdm ( product detector module).... de vu3inj...

    Dev Rama Prabhu A small 13 dB gain amp would do because of the diode DBM which is lossy!
    Normally the loss of diode DBM is around 7dB to 9dBso excess gain should not be used!
    Happy home brewing!
    By the by 12 dB gain = 4 times voltage gain!

    Kalyanasundaram Ramachandaran Around 10db will ideal.

    Indrajit Sinh should i use high ft transistor c2750 or common bc547 for 40/20 meter front end , calls A,wideband 3:1 balun transformer as load , secondary connected to dbm......

    Dev Rama Prabhu Better to go for 2N3866 as it is strong signal low noise amplifier!

    Ron Mallik 2SC3355 will easily work with 30mA of current at 9-10V Vce. Amazing noise and IP3.....2N3866 very dubious these days..."printing maal" as per local trusted dealer


    Ron Mallik Indrajit Sinh and others: IMHO the electronics is not the main problem. How skilfully you wind your magnetics, will play a big role. For example, the original designer may have carefully wound the bifilar coil with say uniform 8 twists per turn and spacing them evenly on the toroid. The novice did everything, but wound the coils randomly (anything but broadband ) and did not check for phasing: same electronics, but it doesnt work in the latter case! Designer gets bad name but HOW designer will document his skill and experience

    Ron Mallik For 40/20m BC549C is great.....10mA Ic is enough! We should not also ignore the C9018 transistor. It is a brilliant but cheap device. The vendor will make a BIG difference though.....Better to locate Fairchild/Onsemi 2N3904 instead. Atmospheric and antenna noise is much higher so do not bother about noise figure at these frequencies!



    2SC9018, 2SC9018 Datasheet, 2SC9018 AM/FM IF Amplifier, buy 2SC9018
    futurlec.com


    Indrajit Sinh i fully agree with Ron Mallik on the toroids winding. infact i have written on it in my blog. pahsing and twist no problem. will go for bc549c yes C variety.... as the rx is just for checking the local signal during the testing phase of the transitter... it will be use will similar to FSM. i will be listening on my tic tic and adjust the tx.... as for 2n3866 its a good one but in the market they sell two variety one cheap and one guranteed so not buying any2n3866
     
    Indrajit Sinh for the bad name :: designer has to really write two type of writings. one as a normal they are doing and one very extensive one ( like i do with writing down even a trivial thing, the process, what i thougt and what went wrong and how i got it corrected etc ). second type of writing we dont see any... that was the reason for me to re-invent wheel dialogues.... lets hope by doing thought churning something good will come out... ( i am not a designer just a reproducer, jugadu...)

Sunday, December 7, 2014

14318kc , ra3aae dc receiver

I had made the linear (25w) using the IRF510 for pumping the radio waves into the ethers. At present only 20 meter antenna was known to work. The 40 meter dipole has the possible coax problem. I have long wire also. But I thought to test this linear on 20 meter due to constant traffic on that band.

I had the ra3aae receiver prototype receiver to test tx on the 40 meter but nothin on the 20. I also wanted to  modified original PA2OHH design for the INDIAN conditions. So made this receiver for the 14318kc cw/dsb tx using the 7159kc crystal.
Will house it in a neat sleek box so look like a walkey talkey.

Hope to monitor it for long range.
***************************************************************

building blo
RA3AAE, Poliakov sub-harmonics mixer. by VU3INJ, Indrajit sinh 04dec2014

Diode mixer for amateur :: At the first glance we thing that how the lowly doiode will help us ? But, fact is that they are easily available, very simple to make, gives a very good result, they have high dynamic ranges... can process small signal as strong signals.

In this particular detector, i have made atleast 3 prototypes on the three different frequencies. Now, it is safe to say that its a reproduceable design.

Block diagram:::

First stage is the BPF + RF amp, Detector, AF Preamp, AF Amp. Xtal VXO, ( power supply, antenna and speaker switching, casing etc Hardware).

List of components:::

Ckt Diagram of the first version as derived from the PA2OHH.

This latest Working Version. :::

Tips for building it on copper boards. :::

Problems and solutions.:::

I did not encounter the problems. As most of the problems were solved at the first prototype. Be symmetrical and dont hesitate to use liberal adhesive to solder the copper pads on the copper boards. You will need crocodile clips to hold the components and pads togather. Use wood for giving support during cutting. Please cut the copper carefully so that its straight & clear. Carefull during toroid making so wire does not get shorted.

From this where ?

Its a serious toy. Can impress with childrens. As a gift to new local swl for listeing your signals or as a single frequency local net receiver. field-fone... 


This receiver is  housed in the metal box but i think you should place it in a plastic box. works okey in monitoring my own tx signal i.e 14316.04kc beep beep beep.........

 


 14318kc receiver



QRT-november2014

For some time I was not able to post into the blog due to some minor technical problems of the cookies and something else but hope will be able to post here some more experiments done during this times.

During that time I had created a facebook page to upload my images here is the link https://www.facebook.com/pages/vu3injblogspotin/752990588098632
I have seen that when you upload the images to facebook its very faster than blogger and the software at the websites makes your images light so it becomes easy to upload on this blog.

If hand drawn image please use black pen to sketch JPEG formet is ok.

I am maintaining this blog as well as the facebook page.

ON AIR 14315KC,  will be installing the single frequency set-up....

CW

CQ CQ CQ DE VU3INJ
CQ CQ CQ DE VU3INJ VU3INJ VU3INJ AR

VU3INJ DE***** **** **** KN
TNX **** UR RST 599   5 N N  KN

PLS QRS  QRZ  DE VU3INJ.

VU3INJ UR RST 557 KN
**** DE VU3INJ CU AGN TNX.

CQ CQ CQ DE VU3INJ

Tuesday, October 14, 2014

Mixer TA7358

I have used the FM FRONT END ic ta7358ap (LA1162 etc) in the mixer for arriving at the 7059kc in 40 meter band. During testing the old tech school VWN tx I needed one stable frequency as 7.159 MHz xtal was not available and at that time 7100-7200kc band was also not available. so this was on hand and it worked.

***
As of the 7dec2014 I have got the crystal due to a generous help from the Delhi ham friend. Hope to put the 40 meter VWN TX on this 7159kc

Friday, October 3, 2014

y2kissrx

Around the year 2000 when it was written as Y2K and we had to fix the bug of dates , I made one homebrew receiver. It is still giving me loud signals. you can download the pdf files at the Indian Homebrewers facebook group.
thanks,
de vu3inj
***************************************
it is being written up and uploaded as pdf file in indian homebrewer group in the facebook.
y2kissrx1.pdf contains brief details and essential components,
y2kissrx2.pdf about testing and dbm making.
y2kissrx3.pdf about completing it (IF making, IF Osc, RF osc, AF, IF, RF Amp stages etc (work still in progress)

 

Thursday, August 7, 2014

ETCHING A PCB (old tech)

I have started etching the pcb on the old style, with oil paint and brush using the free hand drawing small non critical pcb.
it worked out good . will soon publish the foto graphs of the process. its an 80 meter oscillator and buffer.
***
Etching the PCB

From my last visits to metro I bought glass epoxy pcb 1foot size, prize rs.175/- .

I needed something to etch. I was very busy. Now, when I am not working for govt, I have to put more quality hours for family ,works etc and its little odd  for me. So, I started  with a small simple thing first carved out 1.5 inch by 2.5 inch piece from big board by small hacksaw.

Then bought small FECL3. Ferric cloride. The dealer did not give me big bottle but  a small bottle for 50/- even that was half empty. Due to rainy weather this fecl3 became semi liquide from the crystal powder. Ok.

I can not find the small size drill-beat , so will place the components as  SMD style without any hole. The pcb was traced as an island pads with lots of ground plance to sooth the rf. Oil paint for covering the copper to protect it from etching. Then  let it dry for over night. It did not look like straight line but just work of the picaso ( the artist). In the morning I could not find it dry so, used a simple  fan to throw air on it .PCB dried somewhat after 4 hours.

Then put PCB into the solution for etching and after one hour it started eating up the pcb. After rinsing I will see what it looks like. i used small glass bowl for etching container. You should never use metal. Use plastic or glass. It is possible that material may stain your workbench, so i put the bowl away from childrens in verandah. within 1 hours it started eating the copper and around 1 and half hour it was done.

As of 28 april 2015 . I have downloaded and installed the student version of the deeptrace.exe. the pcb design software. Its very good one. It has everything needed for designing the professional quality pcb.

On suggestion of friends I tried the H2O2= hydroge paroxide, HCL-hydrochloric acid. Pour about 100ml of h2o2 in the plastic bucket. Then gently pour the hcl. put  the pcb and within 10 minutes your pcb is etched out . Clean it with water and its good. Etching process if very faster , even with this.

Earlier I was using the fecl3 but that took lost time and was not good.





Sunday, July 6, 2014

How to etc PCB

Just few hours back , in Mumbai we had a very warm eyeball qso with OM Cyril and OM Sudhir bhai shah and OM charudutt.
In the island of shops I was not able to find the copper board but VU2UPX led me to the visha electronics on the third floor off lamington market on main road and I had my second big copper clad board after a two decades. first time I bought big copper board from Ahmedabad. ok, glass epoxy cost me around175rs/-, normal phenolic is 75/-. size is 1 foot by 1 foot.
I had used first copper board for making the VU2ATN 20 meter transceiver with mc1496 double balanced mixer. zeroxed the ckt layout from EFY magazine. Then to make it transparent applied oil to the papers and let it dry. then with the help of pensil and carbon paper traced it on copper board. Now, ball pens ink was used to mark the traces by hand. when it solidified after some time and tracks were visually checked with EFY magazines original layout. I finally put the pcb on a small lunch box poured some water and then goes the ferric chloride may be two or three table spoon. then let it eat the extra copper and atlast finally after an hour the copper board was taken out. seen that everything was done properly. satisfied, washed with water. then with the help of soap and kerosene it was cleaned. finally I got my firs etched pcb.
This is a very old tech. So, I feel at liberty to ask my junior hams but very seasoned in this etching pcb to help me out with latest techniques and here comes the reply from my friend JAYDEEP BANERGEE (VU3JOJ )I have seen he has made very good pcb better then professional quality.
with his permission , I reproduce his reply. Let it be verbatim. I hope it will be helpful to my friends. Foe any queries and question please call him up directly. He will be willing to help you out. He is available on gmail and facebook. thank 3joj.

HOW TO ETCH A PCB

For a professional look of your pcb I suggest you to follow what I learnt at my university of life.

  1. first clean the surface of the clad board with soft scotchbrite. Do not press hard. You do it to remove the weather coating of the copper board.
  2. Then clean the copper piece with soft cloth or tissue paper by pressing hard. The cloth/paper will become black. Then moisten another clean cloth with (no tissue paper) Acetone (if not available use spirit) and clean again until no black spot come on the cloth.
  3. Before preparing the clad board (step 1& 2) you have to print the negative on a thin photo paper by tuning the laser printer in darkest mode. You also have to turn off the page scaling buttons of printer properties. Use photo paper because toner is not glued to this paper. If it is printed on a normal paper the image will be permanent and unfit for transfer on copper.
  4. Now follow step 1 & 2. and place the negative on the copper clad board. Fix it with paper cellotape at corners to prevent displacement while ironing.
  5. Now heat your iron to its full capacity. Place the copper board under a layer of a thick cloth ( I use my worn out denim). Remember the surface must be smooth for ironing.
  6. Now the main secret. Do not iron initially on the paper side. Put it in up side down position under the thick cloth. Press iron hard for 30 seconds. Now reverse it ( put the paper side top). Iron light for a minute. Stop for 30 seconds and then again iron for a minute.
  7. Now keep the board on the thick cloth and iron directly with light strokes until you see the pcb tracks.
  8. Left it for cooling. Do not dip in water. Try to peel off the paper gently. Now the whole toner is transferred to the copper. The paper is absolutely blank.
  9. Using a magnifying glass examine the tracks and if you find any paper residue wipe out with a soft brush. If you find any track missing or broken then paint with Erase X Pen ( permanent marker will not work)
  10. Now dip the board in FECL3 copper side top position. Always cradle the container lightly until unwanted copper wiped away.
  11. Clean the board with plenty of water. Do not drain the fecl3 solution. Keep it in a glass container with big mouth. For next etching just add little fecl3 and it will work. It is also illegal to drain fecl3 in foreign countries. There is scientific procedure to dispose it off.
  12. Now wipe the board with VIM dish washer and scotchbrite until it is shining. Then dry it with a cloth and again wipe with acetone or spirit. Then spray ACRYLCOTE on it and leave to dry. Then spray the same on the reverse side olso.
  13. Drill holes. See my homebrew drill on facebook wall.

Wednesday, May 7, 2014

vwn wire antenna

Wire antenna experiments



Little lamentations

I opened my logbook and saw that for the last month(april2014) i have been not doing any HF or the usual SWL ! A month of absense.... People were claiming lots of contacts within a day.CW,DX etc etc band was very wide open, this happens very rare.

In the social media i wrote following lines and become QRT to examine the faults with my vwn transmitter & antenna systems. I was in deep anguish, lost hope so much that i shunned my self from other projects. Reason not able to radiate effective power to even neighbouring hams 100km. Lots of things were at stack. It was my reputations, other new-hams hopes etc....

But, in actuality we have very few hams and desnsity is really very low. So, what works in europe and amerika don't work in VU.  we need more than 5 watt to communicate.

Antenna

Research going on...... saw lots of articles on the inter-nets. atlast came to the conclusion that for 40 meter i have to increase the power. May be my some power might be in harmonics also. Raise the power from 5 watt to somewhere about 50watt... as well as make some wire antenna, i.e LONG WIRE, MONOPOLE VERTICAL, END FED HALF WAVE.INV-L,

Please note that , Inverted-Vee, FULL DIPOLE dose not work as a first antenna. All the myth of loading the antenna was shattered. I dont have atu, gdo, antenna analizer etc.

The more i read the success story, one thing stood out, that they used some sort of tuning, be it a simple lamp, variable capacitor or atu. In the past sought indian hams with vwn transmitters, used the dipoles strung between the coconut tree. I never herad inverted Vee or long wire. For the first antenna anyother antenna is not recomeneded , instead Just strung the wire.... and tune it with ATU, AMU ETC. Fact is, no body hinted this to me. Its not their faults. Most of the hams have commercial gears and producing 100 watt powers. So, basically there are very few hams who works QRP/p. Piece be on them. They dont have first-hand experience of real homebrew qrp and its challanges.

My systems


My all systems are homebrew from the scratch. It does not have standard 50ohm input, output or anything standard at all. Standard comes from the quality of measuring instruments. which i lake (its a candid truth). That was the reason that i asked fellow hams, who have successfully brewed some transceiver to pass one of those working trx. Nobody understood it. Instead the formula of "teach a man how to fish instead of giving the fish was enacted". Well, what i can say on morale standards.... they are my friends and helped me without any gain.

So, person has to make everything on his own and when he makes it , he is so much harassed that he don't pass on the informations to others and same cycle of frustrations goes on with another fellow........ one day he buys some second hand tx,rx and enjoy the bliss of commercial gears. Even in the second hand saling- there are few cheats who dump their non-working junked sets on others.

Big Sorry

Please don't get offended due to my candid words ! I brewed the tx in last year, 2013.... and it is still in the self idling..... group effort is needed to put a person on air. I know lots of friend called on me, we fixed sked and they tried hard to help me. My sincere thanks goes to them. That your effort, constant words of sympathy and comments is keeping me on.

Field test

i compared the tx signal strength with inverted vee it did not go even 100meter. Then tried long wire fed at one end without any tuning. what a brave person i am to declare the results..... it radiates more than 100 meter with 599 report. i will test it for few km and then will make a tuner. 22swg, about 70 feet hung between two trees.

As of 7 may 2014 made a test receiver using the ra3aae detector. I am operating the 9volt pp3 batery. will ride a bike and go to few km listening it. if it gives me 599 signal in the city area within 10km then will tell you friends.

{As of 27Jan 2015 I know the main culprit is two fold. low power, unturned antenna. For first try brewing the linear of atleast 20watts. Second  antenna. Now I will try this antenna with 20watt linear}


Well thats it folks. when wheel starts working you will know yourself by tuning on 7059kc , 30seconds on off pulses , 5watts, cw carrier. if you hear me please call me on my mobile number and we will have a sked.

(27Jan2015   SKED:- May be using the R7 Dayton receiver and this vwn cw tx + 20watt linear you might hear me. will give you a call when ready....... )

Realizations

(19august2015 As I gifted my VWN tx to a ham friend and linear was made only for 20 meter. Busy with many things etc so did not test anything. But, meanwhile realized that  antenn is good, tx is good but I need the damn 20watt... so once again repair first VWN transmitter and do the test... or instead of re-making for all projects. Make a linear for 20/40 meter and test everything....
)

Wednesday, April 23, 2014

Dummy Load

To give a standard Lamp-test of the  VWN 40meter a lamp was needed. This vwn tx uses  the premixed 7059kc (11059-4000 kc xtals) as reference oscillator.

First Tried the kcommon electric lamp. It did not work. Then went for the torch light lamp.

Searched, in the general stores, paanwalahs and all sort of peoples who used to sell the torch lights and electronics related goods. No way. One gave me a fused lamp for rs10/-. then i was watching the autor rixa repair job in the station area, wow its tail has the good old lamp. i asked repair man and he said two types of the lamp are used. one is 12volts, 35 watt as head light and other is the 12 volt, 5 watt as tail lamp. Oh my god, i searched the entire city and they were found near my qth and this 5 watt lamp is cheap also. Just rs.5/- per pices. It will be available for some more time. So, this is a standard and cheap thing.

When i used the 5 watt electric light lamp, i could not get it lighted up in the transmitter. so was worrying whats wrong! is it the transmitter not pumping out the oscillations ? whats up mate !

Now, found the solutions in the form of ohm low. here is little maths to muse.

for auto tail lamp:- it takes 12 volts dck at 350 mili ampere. which turns out the about 33 ohm. near about the real dummy load of 50 ohm.

for the electric lamp:- by this ohms law resistance becomes very high and not in the viscinity of the 50 ohm. thats the reason for qrp  i could not get this lamp lighted.

v= i * r, v-volts, i, currents, r - resistance,
w=i *v

Thursday, April 17, 2014

RA3AAE detector


I had tried serveral projects of ra3aae detectors PA2OHH and KE3IJ . Well before these projects, i had never worked or heard of it. Both hams have good projects on their website. worth to see it.


My experience of these humble diodes have been nice, diodes always provided me a reproduceable results.

During brewing of the  first 40 meter receiver and then second  48 mhz rx , i found that some peculiar problems. i.e noise, antenna mismatch, microfonics, sudden breaking of audio oscillations etc arises, i tried all my tricks to get something which others can use.. but i did not work. so left it.

( (6meter tx and rx (ra3aae) experiments. & RA3AAE detector )
(Please visit my earlier two posts to get reference of things i am stating here.)

RA3AAE detector has the reputation of "works on first trial". so little puzled  and after some rest and new lights, once again tried to tame it. here is the results.
hello cq cq can you hear me !

fsm meter , what a simpicity








































For starting the test,

i put these modules in the workbench once again.  gave cw tone okey. it works but it did not give the performance i wanted. Audio is little odd.

I said why not make another ckt to understand this ckt.

Then it was time to make my third detector from the scratch i started with audio amplifier first. hmmm, BC547B based af pre-amplifier stage, LM386 based audio amplifier. Ok.
 
Made a dedicated amplifer for the detector and then i tried to reduce the gain of lm386 presto ! sound is crystal clear.


Now ? let me first test it with existing detector. so, tested and within half hours understood what was the problem with earlier ckts - high gain audio amplifier.

LM386 problem and solutions.

10mfd placed between 1 and 8 pin is not needed. No need of high gain. How much high gain 200 times. Without 10mfd only gain of 20 times.

In AF pre-amp stage feed back of 100pf improves audio quality and reduces noice .

From 12Volt dc, 1amp capable power supply, whole radio circuit takes 40 to 140 ma. When i connected with 9volt pp3 batery it took 19.1 to 29.1 ma but on high volume it breaked into uncontrolled oscillations. may be with high impedance source i.e low current capcity-source. cure is to place 470mfd to 1000mfd capacitor across the power rails then af amplifier works better.
(kindly read handwritten notes will write it down shortly. Please.)
Antennas:-

a small piece of 1 feet wire was connected to the high impedance side of tank i.e top of it and signal came rouring. Night time BCB, other hams signals to be observed. In subsequent night observed. It is okey. there is slight BCB.But not too heavy. You can safely put headfone.

I want to connect the dipole and reduce the qrm so two tuned ckt will be employed in the front..( aantenna work is in progress, )
ra3aae detector problem solved

design on paper

af pre amp stages

conclusion too much gain in the audio stage is not needed as we are providing the bc547 based rf and af pre amps.


Failure of my ta7358 ( see earlier post)  might have the same problem, excessive gains. ???
(when i tested this theory later on ta7358ap has started behaving good )





Impedances:-

Here,ckt has been taken from pa2ohh. we are using the 470 ohm and another 1k pot with diodes so the impedances are high. Not just 50 ohms. Keep this in mind. So, when i tried the CB af preamp stage of KE3IJ it did not work with this designs. KE3IJ has intentionally made this cb amplifier to adapt the 50 ohm dipole antenna. wow.

Logic behind the designs.

when we adapt two stage from different design we should also take cognizance of the impedance they are looking and many of the time failure of the ckt is due to the mismatch in the impedances other wise individually they are working fine.

so, we have to first understand the logic used by the designer for the given module and for that we have to make the ckt as designed. they dont tell us variable ot the processs but it is possible they have worked hard to arrive at the single design after lots of other variations tried. My sincere thanks to all the designers.

Actual ckt diagram which works. 

After long long evaluations this ckt diagram is tested okey. I made it on perfboard. You can make a small pcb. If anyone makes pcb please let me know. I want to upload it so other hams, swl also benefit.


 
40 meter receiver using ra3aae detector.

At last i can say that these ckt works for the 40 meter.

(48 mhz will be tried after making suitable LC local oscillator of 24mhz.)

Local oscillator

For local oscillator i have used ceramic filter running a collpit oscillator..tuning is by a small variable capacitor. i have itentionally not given the oscillator ckt as also wants to test the other normal Lc Oscillator.To be frank tuning is very sharp some short of slow tuning mechanism might be need if you want ssb. otherwise for cw it is okey.

(as of 20april tested the oscillators and found that one with the ceramic resonator 3682kc , two terminal devices is more stable then LC oscillators. I was waiting for this test. thats the main reason did not write it first place. No two oscillators are same. I made three oscillators, one did not go to the desired low end freq 3530 instead it stick to 3639 one was going easilty and one stood at 3531kc ! so, first of all measre the frequency and then use it in receiver. make few oscillators and you will know which works and which does not. ckt is given below c1 and c2 are 1000p styroflex or any good capacitor, vc is variable capacitor use the radios gang .n.b i will upload the test result of the vwn tx done with the help of this radio and more on next post. thanks...... )


Other things.

Will be putting more musing on LM386, AF preamp of DC-40 of VU2ESE, oscillators.

I have no local population of hams so not tested ssb signal or cw signal of other hams. Also not connected big antenna. I want it be mobile to test my own transmitter and to check pheasibility of running SOTA . I live near Mount Girnar. One of the highest peaks.

 If, in sought india someone try this ckt and give me the result . i will appreciate the effort.

we can safely demo this ckt to childrens and novice hams for their first real receiver. Sound quality is real good.

In the end

Lo needs to be tweked, But, all other stage are complete and  there will be no further R&D.

Once again put into a permanent box and will let you know.

Thanks folks , lets use this wheel with great cheer. 

(During the testing my vwn tx on 7059kc gave me company and one of the days will be mobile with this rx and find out the range !...  and will conclude whter my tx is really low power or it works few km as i thought )

Let me cite the todays elixir from 
His Holiness the Dalai Lama,
the very purpose of our life is happiness, which is sustained by hope. We have no guarantee about the future, but we exist in the hope of something better. Hope means keeping going, thinking, ‘I can do this.’ It brings inner strength, self-confidence, the ability to do what you do honestly, truthfully and transparently.

Tuesday, April 15, 2014

novice 90

You have transmitters or made one QRP.

WOW ! congratulations for hardwork. Lets have a QSO. You connect it to the dipole and presto there is no signal of 40 meter tx even 100k far ! You make another dipole. tweak it with magic formula found in net. It does not work. get frustrated. request for listening and it results in the downgrade of reputations !

Antenna Not Loading

and blame on your hardly homebrewed qrp tx.

No one is to be blamed except the murphy. The problem of QRP tx not loading on the antenna is age old. Even in the 1959 it was there. One of the ham friend has given the solutions in the form of novice 90 antenna.

please search the google and find the original novice 90 from the popular electronics pages.

I will be putting the source of these resources with note of thanks to original authors. I am trying to use the theory for my communications and writing it in a story style. Technique which works....... if it works for me , then it will surely work for you as i am going to make indepth analysis of it......

Now, musing over the antenna starts.
novice90
 Novice90 antenna roghly drawn.
lc tuners











Wow ! More i read, more i get confused. what is vital thing ? I feel like in a classical chicken and egg situations, You should have an experience before you get one. Pirates are doing fine with their qrp AM transmitters, and why we hams not able to use qrp 5watt, even though we have the previledge of cw also ?

I moved my self from the facebook and opened my eye towards the things around me.Brainstorming session starts. Series of question came.

What is transmitter power ? QRP or QRO ? what instruments you have ?

QRO amplifier uses dipoles , loops, uda-yagis, beams etc. they are balanced, they work better,even you can find commercial antennas, know how is easily available. most of hams use them. dipole are very user friendly.

But,for QRP transmitters with dipoles i am not able to transmit. looked into the web found lots of things. there are many camps and theories and formulas. Mind boggling things. End feds, Half waves, Shortened dipoles, Long wires.....

 Ok Ok. what about my question "i am not able to load the transmiter ?" i litterally typed similar words on the google and one solutions came -use Novice90. then Monoband verticals, Long wire etc.

For qrp, first experience,antenna should be resonant.
What you mean by resonant ? half wave, quarter wave, exactly measured and then trimmed ( increased or decreased the wire length practically).

antenna have self capacitance. Due to its structure and nearby objects, EARTH etc it has an inherent capacitance. dont blame elements but use it. here you will need a good earth or counterpoise.

two things, first- antenna should be tuned (resonated) for your band/freq.
and second- impedances should be matched for optimum transfer of power from transmitter to antenna.

So, this power goes to other ham's radio.

For antenna tuning you need antenna analyzer MFJ259B, GDO. (If your club or nearby hams have ! then your all problem end within an hour............).

For impedance matching you need LC tuner with some sort of SWR meter. These things might be in your transmitter or you have to make one.

Fsm is also vital for this verticals, sigle wire antennas.
If you have a portable scanner or second ham ins some distance or a friend who can tune into your signal then its better to listen to your signal and estimate the Signals stregth. In the south india there is density of hams are high compared to my gujarat state , western part of india ! so, they have success in ham radio.

quarter wave antenna has low impedance (in the range of 25 ohm etc), half wave antenna has high impedance (3k around)

Using formulas , for a given frequency a wavelength is calculated (that is called electrical length). If your physical antenna ( wire !) is shorter then this calculated value then your antenna is short. If it is longer, then  your atenna is big. for short antenna inductor has to be added and for large antenna capacitance has to be added to 'tame' it down to your frequency. there are all sort of formulas. For us imperical values will suffice.

For insulation, end insulators or support you can use "white pvc water pipe" used in water plumbing. Please remember "white". If it is grey or black, dont use them.

(for this antenna) lower swr alway does not mean that it will radiate more, check with FSM, (Emperical) little mis-match on swr but high FSM reading is okey with qrp.

what is VSWR ?  standaing wave. answer is complex ! but practically be understood by little experiment. put a water in a bucket, with a little stick or pen -vibrate up and down with a constant motion, you will see the waves propagate to corners and move back to centre and due to this to and from movements of waves there is a pattern on the surface. this sort of things happens with rf in antenna, coax etc.

the power which does not get radiated due to this VSWR comes back to the coax, tuner and heats up the coils, capacitors and make complex things... that's the reason for qro amplifier swr should be 1:1, our goal should be to throw last bit of rf power onto the ether....

wave travels in duality. up-down, if we are using single radiator there should be some sort of earth to compensate it. counter poise is a piece of wire which provide earth for radiating element. remember the famous parasets. they used halfvave wire as antenna and quarter wave as earth. good. Military is using this comm. we should carefully see their wwII radio antennas were....

in our novice90 tuner is supposed to be near the transmitter, also the earth is nearby. Warning- long coax line is not encouraged. it will create problem due to return currents, heat, TVI, harmonics interference to (the legal services, very bad , if your shortvave tx harmonics interfere  neraby police  station vhf ! an ugly situations is ready for you. wpc is will be late but they will reach to you first with siren blaring wehicles ). hence we dont find this antenna in a full power or medium power transmitters, commercial transceivers. Thats the reason most hams don't use this atenna.

This is your first antenna. and with upgradation you have to migrate to other antennas. happy ! thats why you will not find anyone using this antennas but it works mirculously first time and any time, good for camping, temporary, clandestine work (he he) etc ......Don't loose hope. It worked for 1959 American Novice and even today it will work for you, me with just 5 watt.

Make a good earth. How?. Make a deep trench of 2 feet deep. Soil should be moist. Bury the old unsused cloth iron plate and few small metal, copper etc things with salt and black coal deep into the earth. dont forget to wrap copper wire for more contact. rod etc. pour water from time to time and you are done. Main element is, there should be no gravels, sands, stones etc, it should be wet. and if not sufficiently wet, then you got to insert a pipe to pour water before use. With multimeter measure the voltage. There should be no drop of line voltage and you are ready to go.

Your local electrical store can provide you the brass plates and little more know-hows,even a handy-man for a price.
In the railways they still make earth for signaling purpose. Ask a friends in the signals department (the PWay inspector or Signal Inspector). They have measuring tool like "megar" a resistance measurement tool. only thier instruments are regularly used in fields.

What wire should be used for L ? for antenna use any wire easily available say "1/18 " electrical wire inside the insulating coating there will be a single copper wire of 18swg. It seems electric wires copper is little different from the motor windings copper...,

Use of copper enamalled 22swg, 20swg is ok, still better is 18swg. copper enamalled will cost less then common electrical wire. You can scrounge the copper wire from burned winding of big electrical motors. but buying new is really cheap.

peoples have used the normal aluminium pipes in the telescopic fashion (fitting one end inside other pipes end) with success as monopoles. here you dont have to worry about supporting the wire or buying the bamboo. this is also a good option. but care should be taken to tight fix the aluminum. as it can not be welded. better mechanical works gets good results.

40 meter is all day night, all time band. terresterial. (neighbour hood band if there is no local qrm due to mobile tower smps etc) for a given place,situation one antenna works and for different place situation that does not work!

There is also another third options. As the legendary spy set and paraset transmitter used. halfwave as antenna and quarterwave wire as counter poise. I think i will try this last antenna first and then other things. or may be make all the antennas.... or may be somehow use the QRO-linear..... and not try any of this.

Brain storming ends here. What a topsy turvey journey.still there from where we started. thats called chicken egg problem.

Now,,,,,I am making ANTENNAs and will  upload more fotos, end results. And possible first contact.using vwn tx.


mp-10, minipig
 this is the simplest bridge to handle the qrp tx.

I intends to make this led based bridge to get hang of the swr meter.
antenna and tuner coil. short antenna whip, vertical, half wave , long wire.... all sketched on paper same but, there is big difference.....






(to be continued.......)