Corona and free time

corona and free time.
i was passing through the lock down of the society. What to do ? well i thought why not finish up some project in this free time created by the corona virus epidemics.

Ok, heated up the soldering iron. Humm lets me put a delta loop for the receivers. Soldered it then suddenly found that my soldering iron is not heating up. It gone kaput. look how innocent it looks. Tomorrow morning i have to goto the shop and find the coils as well as the soldering iron. This was a very nice one.

Then repaired the power supply. After a more than a years silence , i have forgotten where are my small and big instruments and all those things. What i am dooing.just putting back my linear of 15 watt and 20 watt on air. i need to box it finally. Each time i use and then store and use, requires tinkering is a wastage of energy. So, box it. non-use then pack it clearly.
27-03-2020


I revamped the linear , boxed it. It gave me the 15 watt RF power when i used it years ago. Fixed up the dipole wires which were handing , bound it and seen the coax for possible corrosions and loose connections. NO. looks goods.
Finally on the forth day of lock-down i tried the SMOKE-TEST. Then  hesitantly put the power supply to exciter and linear. No current consumption. No RF. Sucks.  Linear seems to OK, there is no shorts voltages are ok. fine ? idle current ok. 100 mili amp. Where is problem ? exciter is a trusted one, and i felt there is some loose connections. Hmmm, tomorrow. will do it agains. Something is wrong will fix it soon. Got plenty of time.
Sunday- ohh today is sunday. Every day is sunday. In the morning had the darshan of hanumanji. Then day-time thought of doing the repairs, as my eyes needs lights and spectacles to see clearly. Tested, First IRF510, greased with old heatsink material. heatsink bolts tightened. All bolts unscrewed. Seen for loose joints. Etc. 2n3866/2n2219 is working good, heating up. IRF510 olso shows current variations on the bias preset variations. earlier i though it might be kaput. Then went back to tune buffer stage, it had voltages. switch is working fine.Then finally to source of Rf , xtal oscillator. Hmm , it is not showing the CW note in receiver. Then i removed it. put on the 12 source, tried to hear the CW note. It was there but buffer was not showing any power increase. Then i was touching the transitor and the emmiter follower was very very hot. Hmmm, the classical problem. Removed the BC547b and the CW note was bit stronger. Resoldered. Connected. There is RF power, but how much ? undetermined. After testing the linear i will know whether its worthy of putting on the air.
30march 2020- changed the faulty preset, replaced with 2k preset. But connecting wire broke replaced. When we are making the modules, it should be housed in a a seperate box to save from the dust and all other problems. As this was first made transmitters, i did not know that. Now, every small modules has to be put into its own shielded box and use of connector wires to easily connect and disconnect. with time we progress. Anyway it is once again starting working. On dummpy lamp it shows true brightness. ohh good. But, will it be loading the dipole antenna is a question. Hope,wire is ok. Need on air testing. Tomorrow. I know it can punch a hole.though india. want to make two frequency xtal 14.000 and 14.318. will try 14.005 for cw.  It needs a suitable poliakov receivers as it is cool one or may be other DC receiver. Lets see.
35 volts suppply becomes 27 votls with around 850 miliamp current.  sums up 22 watt DC input so more than 10 watt Rf is there. And i think with it DSB exiter might also work.

here is my
1- receiver strip the 20 meter Direct conversion receiver
2- 20 meter linear 20 mb linear
 3- RF linear CW transmitter 14.315 mhz
have a look please.

Now, first part done next is to put it on air and re-generate the QRM.