7159 kc dc receiver

               Here is the foto of my finished receiver assembled during Diwali holidays.  All modules and box was made earlier. I assembled it or to be exact reassembled individual modules made earlier for different project. Put. A xtal qrp tx on 1/4 wire antenna. (for this transmitter see this post :- https://vu3inj.blogspot.com/2014/12/7159kc-beacon-cw-tx.html ) .
receiver sounds good. Tested enough. Now need to increase tx power and see whether i can be received on 7159 kc xtal around 100km ?

i am putting the front end band-pass filter to load external antennas. its a very standard design i used with my other 40 meter xtal receivers.

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Here is fotos of test transmitter.

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.

6meter tx and rx (ra3aae) experiments.

     Small transmitter

48mhz canned oscillator

local oscillator

pin details of can

Why this receiver

              There was a need to make  small RF oscillator for code practise and demo.  It was my deep desire to know far the small canned oscillator can work as some hams claims ! Is there any justificatins in the claims. Only way to know is test it yourself or beleive them.

             I had some 48Mhz canned xtal oscillator. Also i bought from metro, few 24Mhz fundamental xtals. This does not fall into the ham band but if you have the canned oscillator worth to try it.

     After initial successful testing 40 meter receiv er (PA2OHH design, see the march 2014 post) it was found that in the receiver, audio is bit noisy.

            In the KE3IJ (160 meter/40meter receiver design) there is one Common-Base amp stage. His callsign also contains 3IJ , my callsign is 3INJ ,what a remarkable co-incidence ! we both are brewer.
 

Transmitter

              Now, soldered the oscillator-transmitter and RA3AAE receiver. Will test it for range, antenna and all. 

Testing

          Powered up the tx. Switched on the rx and no tone. On increasing the volume it breaks into the oscillations. There is less noice unlike the common emmiter configurations but it breaks into the oscillations due to the  high gain of common base amplifier stage ! solutions- decouplings. or once again use noicy CE stage.  Ok. This receivers AF stage works. switched on off the QRPp tx (!). but there is no CW tone. RF probe shows tiny lights as it is very low power ( may be 10 miliwatt its not an issue).  Are they on right frequency ?

        Measured the freq. 

        48Mhz canned oscillator. reading shows stable 48.000.30 . thats OK.

        24mhz xtal oscillator shows some what like 24.020.5x

 OK. That means 24.020Mhz after the 24mhz it is up by 20k and on doubling it result into the 40k. No human being can hear it ! only BAT can hear hello cq. 

solutions, due to the VC (trimmer) freq is up,  Try to pull it down with L- a small inductor. But, this 24mhz osc is little wobbly in 100hz range. Put a little filter rc in the +vcc of osc.done not much improvement.

25march2014

         I am writing this on, day by day but will publish after all process is successfull. As one of my friend remarked is it working or not ?

28march2014

the thing which started out as the fun and simple is turning to be a major challenge. Reasons are two. Oscillations very-low freq motor boating due to high gain, and xtal oscillator (LO) is not coming down to even 24.001mhz. I need only 1k to 2k audio tone. Very strange. Tried lots of L and C combinations. It took my whole 3 hours. But, could not bring it down to the 24.005 Mhz. 

So, i will be leaving it and try to cure the audio motor boating first. Then test with the vfo 24mhz instead of the xtal. I think will make it in a bigger board with good audio stage utilizing the LF411, a pin compatible but better than LM741 op-amp ic.

(31march2014)

Deoupler circut :-

I saw this type of decupler in the ARRL dc radio R2 and Farhans(VU2ESE). Well now a days, i am seriously looking into the farhans fone stock website. What he has used and how its used. then look from my collections of the ckt compiled over the years (4 years) from the net. And then at-last the web. But, generally i find the answere from the compilations.

de-coupler

 This decoupler simply reduces the hums, noice going into the low noice pre-amp. It prevents noice coming from line to get into the input and amplified. Its design in not critcal, but use is higly recomended in the direct conversion receivers af pre-amplifiers. You will feel the difference.

VXO

vxo

I did not use the oscillator with two xtals as Low side shif was needed. An inductor was put to pull the frequency down toward 24.000Mhz but i can only manage to get the 24.005 Mhz with inductor -(10 turns,22swg, with ferrite core). So, it is not zerobeating the 48.000Mhz xtal QRPp tx. 

This will be ok with the sound cards-i.e. software radio but for humans ear s  up to 4k  tone is needed. 

So,it will be replaced with normal coil for 24Mhz and beat heard and the project will be declared success. in the front will put a cb rf amp with small whip.

Problem with this type of detectors are when a longish antenna is connected overloading is present and short antenna is not good enough. 

1april2014

It has become april, and project is taking time due to the morning QTH & other activity. I also have to do my share of chores....

Most probably, as shown in the G-QRP magazine SPRATs Mouse Trap receiver, will put a 1k pot in the input for the test.

8april2014 once again got the courage and put it on the table. heated up the soldering iron for an hour. changed few things.Lastly measured the voltages. Hmmm on the collector is less voltages then the base i.e first af stage is not amplifying. needs to change the bias net work. second discouragement was that 24mhz oscillator was not coming down to less than 24,005kc. so, still i will be not able to hear the audio note (10kc) for the test. Tried everything i knew on oscillator includin super oscllator style but no way.... Atlast removed the oscillator and will try it once again. If the compuer was used as receiver i might be able to see the 48kc wide spectrum. Hmm  from that wspr i had taken the ckt ! any way tx stage is okey. rx stage is also ok but they are not matching..... so, project ends here will try to put 20mhz can and with small antenna and batery will test the range. actually this was what i wanted to see.

(to be conitued........................)