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More than 1 km av uhf TRANSMITTER

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p55xp

Member
I got this project from a POST in a different thread. I think it can be a great project, and can easily be used in numerous other projects as a stand alone unit. But to be successful in making this project is difficult like other rf projects:mad:. The project is not a very "hard nut to crack" but description is not understandable, at least the inductor making, and tuning process could have more clearly described.
I am on the way to make one for me. Please help me on inductor making and tuning process Above all who is not a transmitter enthusiast?
Please try to support almost everyone
Also recommend a substitute for BFY90, I think almost any high ft transistor will serve the purpose.
I re-attached the attachment here too.
 

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mneary

New Member
I think you should check in Calcutta first to see what high fT transistors you can get. (The author suggests BFR91a.) It would not help you if I suggest transistors that I have in Los Angeles.

Google helped with the procedure which seems to be written in Croatian:
All elements letovati directly on the plate (no drilling). Assembled unit tinfoil and make a barrier between the transistors (marked green) and L3 can 8navoja of copper wire 0.4mm wire on the body of a 5mm diameter spot BFY90 transistors can BFR91A
You should be able to make the coils using the description and the drawings; please read through it again.
 

p55xp

Member
First of all I must apologies for misplacing my thread; though I realised it just after posting, I was unable to move it under the heading where it is now placed. Thanks.

mneary,
Thanks a lot, you minutely looked at it. I saw the translation before. Practically GoogleTranslate was the only resort before I placed it here. The translation is very poor.
The meaning to me was: 8 turns of .4mm dia copper wire on a 5mm dia former(transistor body?).
Again if you go through the schematic "L3 5 CM wire 2.5 m/m silvered wire" is written on it. Confusion emerges.
Please guide me.
 

mneary

New Member
I am not familiar with the term 'former' except from texts I receive from India. I think it means a support used for winding the coil and is removed once the coil is completed, e.g. any round object. (In America I would use the smooth end of a 3/16" drill bit.)

Silvered wire probably means he's suggesting wire plated with silver (Ag). I don't think it's necessary at this frequency and I think he used wire plated with tin (Sn) or lead (Pb) which looks the same. In either case I suggest a 5cm (50mm) length of 2.5mm dia. copper wire. Tin plating just keeps it pretty.

The Google translation provided all but two words. I was astonished at its excellence. Maybe I didn't find any errors because I don't speak Croatian as you do. English is a particularly bad language to construct in translation because of the strange places we use the word "be". You have to be prepared for this.

The units CM or m/m aren't Metric or Imperial. Probably relate to cm and mm in the text.
 
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p55xp

Member
You rightly understood the former(that partains right form to the coil)!!
But you do not suggest the dia. of the coil. If it is 5mm then 50mm of length would give only little more than 2 turns!
Please give detail of the L3, otherwise I understand all your points.
 

mneary

New Member
Please read everything again. Electronics is about detail. I haven't provided anything new to you. All I have done for you is read the same document you have, and repeated each detail to you as you ask a question.

L1 and L2 are 5 turns of 0.3mm wire. He does not specify the length of the wire used to wind these coils.

L3 is a straight heavy (2.5mm dia) wire 5 CM or 5 cm (I prefer 2 inches or 50mm) long per the drawing.
 
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mneary

New Member
I am sorry to say that I am the one who missed the detail this time. Apparently L3 can either be 50mm of heavy wire or an unspecified length of 0.4mm wire (wound?) "8 navoja" on a 5mm (spot). [edit: Google translates navoja as thread which confuses me further. [/edit]

I would use the 50mm piece of heavy wire.
 
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p55xp

Member
There is heaven n hell difference in the inductance of a 50 mm, 2.5 mm dia. straight wire inductor and that of an 8 navoja (thread or turn) of .4 mm dia. copper wire on a 5 mm dia. former (smooth end of 5 mm drill bit).
Both is written on the schematic sheet about L3.
None of the above inductor is replaceable by each other.
 

crutschow

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Most Helpful Member
Why are you responding to a nearly two year old thread?
 

JimB

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307pavlos

Member
Hello guys, sorry for replying in a 2-years old post, but my project is similar to this. I want to transmit video from my videocamera to a mixing console wirelessly. The videocamera must be wireless because it will shoot on stage in a charity live concert. As me and my friend (we are both students in electronics university) we arent going to be paid, we cant afford expensive tools! Is it possible to design a circuit that can transmit video signal from composite to a receiver near the stage and then via composite rca cable to the mixing console?

My requirement is that the pair of these devices must not lose the signal instantly so we must have a smooth clean video on the other end. I tried with a cheap pair of 2.4ghz tranceivers but whenever i moved the transmiter (in "real life" the camera will be moved) the computer lost the signal everytime, so i couldnt "broadcast" this video.

The distance between transmiter and receiver will always be under 3-4m.


thank you in advance! :)
 

karaapak

New Member
I don t understand much about the transmitters but I made a fm transmitter a simple one that using two transistor, one for amplifying to sound another for the oscillator and sound mixing stage. The hardest part of the circuit was the coil. I used a coil calculating program to find the value needed for generating 88-100 Mhz frequency with together a 10-30 pF trimmer capasitor. So when I was searching fm transmitter circuits I saw some vhf transmitter circuits simple as my fm transmitter circuit, I don t know what is the rca cable but if you make this kind of whf transmitter (analog transmitter) you may receive signals with ordinary television. Also I saw a man build a vhf transmitter for his camera and he was watching his clips on his tv wireless.
 
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