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.

er

Here is fotos of test transmitter.

Linear Amplifier Problem- 3

A friend experienced a problem and solved it. first image depeicts the problem and second image depicts the solutions.

Question :---
My friend Vadivel requested in the Indian Homebrewer forum ::  " Help Needed on MOSFET Linear amplifier. I'm using Linear amp used with Minima TRX. Its working very fine. But the low pass filter is getting too hot / smoke after TX of 10~20 secs. I used 2x TV balun glue together and 3 turns of 28 SWG. SWR is corrected with the use of Pi network ATU. Any suggestions welcome. "

 The problem:---

The RF theory :---

The low pass filter was made with the pig nose baluns. But, IMHO opinion it can not handle the passing of 15watt rf.  If  core gets burned or becoming hot, its probably got damaged due to the heat. Please do not use it further. discard that piece and never use this baluns as filter eliment. they can handle just 1watt.

In my experiments I have found that, You need atleast minimum 4 big pignose baluns stacked for linear amplifier transformer.

The solutions :---

The coil is made over the felt pen body. The sketch pen body is the beast material to make the coil for low pass filter. Its diameter is uniform, widely available and most of the time they are in standard size.

A friend suggested  to use air core. And our great elmer shri  Dev Rama Prabhu say's, let me reproduce in his own word ::
Dear sir, if any inductor core is becoming hot it means it is very lossy! Just replace with one more core as these cores are not repeatable! Otherwise as Mr Rajesh has suggested use aircore and I always use aircore with Teflon formers. 73

On air , part-5

Tale of two transceivers:-

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

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

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

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

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

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

Enjoy,
73
De VU3INJ
INDRAJIT,

Wheel has moved.....

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

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

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

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

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

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

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

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

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

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

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

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