The corona blockade has forced to me to do something worthwhile. If we are able to do even then do not fulfilling our dreams is not a good thing. I wanted a receiver for my 14.318 mhz xtal Transmitter. I have one good single frequency superhet receivers based on RM-96 derivatives but it needs to be aligned and fixed and nothing ready made.
I looked into the junk box ? what i have. few unfinished junked DC receivers and one un-finished superhet receivers ? any worthy candidate. first and foremost criteria a working tested modules. because i did not have time and patients for new RAnD.
Here comes my rescue an old "superhet receiver module " where mixing stage somehow did not worked or may be i did not make the good filter or first IF amplifier was too much bad. I used feed back and all short of gimmics (farhans copy) but fucker did not work for me. Finally dismantled that RF amplifier. Removed the 10 mhz xtal filters. Removed VXO crystals. You can look at that module some pages back.
I had removed the audio amplifier, so found another working the ic LM386. I was heating up the ic oscillating up etc. removed it , put the good air, cleaned up and low behold no motor boating and no noise. Then put the separations shields. These are gimmicks/witch crafts but it works. After putting these copper separating shields everything remains in their boundary ? he he.
Then finally after two - three days soldering and using the good smoothing calming words. the boards is ready with their damsels. Size is very small. See the ball-pen. The women are beautiful. Once our late rev. guru dev ji (vu2dev-sk) had remarked me about my putting the ckt with damsels. I smiled back.
There should be no oscillations, motor boating. There should be good filtering of audio and RF. there should be frequency stability. Everything should be tight coupled and nothing should be loose. Put it in the good mechanical sturdy box.
RX has golden finger test. When you do not connect to the signal source, all gain AF at their maximum and there should be no big noise. There should be mild hissing when you listen very near to the loudspeakers. Now, go away from loudspeakers. Touch the Finger to the input jack or small 1 foot wire antenna and it should start roaring and there should be high noise. Then you have good noise and good gain in your receiver chain. This concept of using a xtal filter for a single frequency receiver is boon for early stages of RanD and point to point communication with dedicated group of friends.
As of 4 april 2020- fixed up the QSK but it seems, it reduce the gain. May be attenuating and increasing the noise floor of the receiver . disliking it. lets see that can be improvised later on. needs to be boxed. found out the noise issue, input 100pf removed to 0.1mfd and signal level increased, it over rode the noise floor. hmm.
If i can use the 7812 internally then i may use the 35 volt power supply itself. This tx chain dose not need more power. just 2 watt. means 300 ma at max. tomorrows deadline, no use of internet but just use the time to fix up relays trx and put the beeps. enough is enough. power supply is still a problem. with peak 35 volts dc input 78024 ,7812/7805 will NOT be able to handle. I needs to go for the transitor for a first drop and then regulator will think of it.
On 05-april-2020. fixed up everything called up a friend vu2exp. due to lock down the qth setup is locked up and living at another qth. ok ok. so thought of checking whether rx is working and can cope up with the tx power. have a look at my 1 minutes YOUTUBE vedio 20 mb test set up is working click here.
As i am fixing up RX in the original tx box which was only for the CWTX chain. little bit of cramped space. As this is copper plane its rock-solid. Ohh i have to tune it also.
Now, it needs to be boxed and fixed in the cw transmitter box with all RF change over , side tone controls. wait for it.
Thats it falk, here i am re-re-re-inventing the wheels.
I looked into the junk box ? what i have. few unfinished junked DC receivers and one un-finished superhet receivers ? any worthy candidate. first and foremost criteria a working tested modules. because i did not have time and patients for new RAnD.
Here comes my rescue an old "superhet receiver module " where mixing stage somehow did not worked or may be i did not make the good filter or first IF amplifier was too much bad. I used feed back and all short of gimmics (farhans copy) but fucker did not work for me. Finally dismantled that RF amplifier. Removed the 10 mhz xtal filters. Removed VXO crystals. You can look at that module some pages back.
I had removed the audio amplifier, so found another working the ic LM386. I was heating up the ic oscillating up etc. removed it , put the good air, cleaned up and low behold no motor boating and no noise. Then put the separations shields. These are gimmicks/witch crafts but it works. After putting these copper separating shields everything remains in their boundary ? he he.
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| vu3inj receiver. |
Then finally after two - three days soldering and using the good smoothing calming words. the boards is ready with their damsels. Size is very small. See the ball-pen. The women are beautiful. Once our late rev. guru dev ji (vu2dev-sk) had remarked me about my putting the ckt with damsels. I smiled back.
There should be no oscillations, motor boating. There should be good filtering of audio and RF. there should be frequency stability. Everything should be tight coupled and nothing should be loose. Put it in the good mechanical sturdy box.
RX has golden finger test. When you do not connect to the signal source, all gain AF at their maximum and there should be no big noise. There should be mild hissing when you listen very near to the loudspeakers. Now, go away from loudspeakers. Touch the Finger to the input jack or small 1 foot wire antenna and it should start roaring and there should be high noise. Then you have good noise and good gain in your receiver chain. This concept of using a xtal filter for a single frequency receiver is boon for early stages of RanD and point to point communication with dedicated group of friends.
If i can use the 7812 internally then i may use the 35 volt power supply itself. This tx chain dose not need more power. just 2 watt. means 300 ma at max. tomorrows deadline, no use of internet but just use the time to fix up relays trx and put the beeps. enough is enough. power supply is still a problem. with peak 35 volts dc input 78024 ,7812/7805 will NOT be able to handle. I needs to go for the transitor for a first drop and then regulator will think of it.
On 05-april-2020. fixed up everything called up a friend vu2exp. due to lock down the qth setup is locked up and living at another qth. ok ok. so thought of checking whether rx is working and can cope up with the tx power. have a look at my 1 minutes YOUTUBE vedio 20 mb test set up is working click here.
As i am fixing up RX in the original tx box which was only for the CWTX chain. little bit of cramped space. As this is copper plane its rock-solid. Ohh i have to tune it also.
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| spart 152, M0DGQ |
Now, it needs to be boxed and fixed in the cw transmitter box with all RF change over , side tone controls. wait for it.
Thats it falk, here i am re-re-re-inventing the wheels.
bravo...novel corona could not stop you.
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