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

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)

 

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.

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.

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....
)

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

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.