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 Post subject: Re: FM Tube Radio
PostPosted: 13 Apr 2011, 06:26 
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Joined: 14 Feb 2010, 13:13
Posts: 663
Location: Lisbon, Portugal
Eagle72 wrote:
and the link to that thread is...

Hi!

Thanks for being interested on my projects. The Hi-Fi tube tuner is here: http://diyaudioprojects.com/Forum/viewtopic.php?f=16&t=3128

Cheers,
Miguel


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 Post subject: Re: FM Tube Radio
PostPosted: 14 Apr 2011, 18:27 
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Joined: 02 Apr 2011, 09:44
Posts: 5
Location: Allentown, PA
thank you, sir

_________________
I'll MAKE it work...


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 Post subject: Re: FM Tube Radio
PostPosted: 05 Jun 2011, 06:49 
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Joined: 14 Feb 2010, 13:13
Posts: 663
Location: Lisbon, Portugal
Has anybody else tried this little wonder?

Now after my latest project (the Hi-Fi FM Tuner), I learnt some good things! I´m planning to get rid of the original 22MHz tuned coil and replace with a crystal resonator simple circuit. I don´t know what voltage crystals can handle, but I have a lot of these and will certainly give a try! :)


Cheers,
Miguel


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 Post subject: Re: FM Tube Radio
PostPosted: 06 Jun 2011, 11:02 
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Joined: 03 May 2011, 15:16
Posts: 180
Location: Romania,Iasi City
Here is a schematic, in memoriam of a Romanian Electronist - G.D.Oprescu.
It is for the URSS FM domain : 65-73 MHz but decreasing the capacitors and/or the number of turns can be adapted to tune 87-108 MHz.
Attachment:
FM receiver.JPG

Here I'll post a short description of the diagram (translated):

By using the FM band by radiostations,it is obtained a high quality transmission of sound,especially through their high frequency transmission, which in normal bands receiving stations, where long, medium and short are actually suppressed.We refer of course not to be radiostations in particular trade or amateur traffic,but the music programs transmitted to the public.

Another advantage of using FM is constituing the modulation type, frequency, leading to a audition without athmospheric or industrial parasites.The benefits brought by FM radio stations which are ultra concludent, the majority of radio technology devices are equipped with FM (also called U.K.W.).

Modifing the antique radios for FM reception is not an easy operation, so it is prefered to build a separate tuner for the FM band.

Figure 1 is a schematic diagram of a receiver that combines both functions, either as separate receiver, or as adapter. This solution is cheaper and easier; he works as an integrated receiver with a rise in speaker less than 1 watt power more than sufficient for a large room, if you realize that the handheld devices with output power transistors have the order of 50 ... 200 milliwatts.

The device can be used, for example, to print on the tape where the FM programs, being provided with a standard plug outlet on the tape.

The antenna can be plugged either at terminal A1 in the case that using a dipole antenna where ultra descent ribbon cable with impedance of 300 ohms or the coaxial terminal A2, in case he still uses a dipole antenna but with cable The descent shielded coaxial, 75 ohm impedance.

Here are the details of the radio construction:
Domain: 64 ... 73 ​​MHz (in fact larger by + - 5 MHz).
Sensitivity: better than 250 microvolts.
About 1 watt output power with up to 5% distorsions.
Power consumption below 20 watts.

L1 and L2 coil is wound on a single housing with adjustable core ferrocart for 8 ... 10 mm
L1 coil has : 3+3 turns, Cu Em 0,2...0,3 mm
L2 coil has : 5 turns with tap at 1.5 turn from the ground, Cu Em 0,6...1 mm
L3 coil has : 5 turns, Cu Em 1,5....2 mm,wired on a cylinder with 10 mm diameter
L4,L5 and L6 coils have : 35 turns, Cu Em 0,1...0,15mm

Output transformer core laminations twisted a section of 2 cm square, 0.1 ... 0.15 mm air gap
Prim: 3500 turns, Cu Em 0,1...0,15 mm
Second: Cu Em 0,45... 0.6 mm,the number of turns is depending with the speaker impedance (eg: for 3 ohmi / 45 turns)

Electronic tubes used are as follows:
T1. T2. T3 = EF80, 6AC7, 6Ж4.
For tubes T2 and T3 may be used 6Ж1П tubes.
Tube T4 = ECC82, 6SN7, 6H8C, 6Н1П.


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 Post subject: Re: FM Tube Radio
PostPosted: 29 May 2014, 04:43 
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Joined: 26 May 2014, 02:56
Posts: 1
Hi Miguel,

I've see your video on youtube about the Fremodyna receiver! Great work! Good sound quality.



Me too I'm working to build a FM Fremodyna receiver... I think the schematic it's the same. But I'm curious, can I ask You if You can send me the schematic ?

Kind Regards


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