RA 40

RA 40

Thursday, December 17, 2009

5 Transistor RX FM 144 Mc JF1OZL

5 transistor 144MHz FM receiver

In order to hear the 2m FM band, I made a simple radio.
In these days I began to use the transistor having ft over 1GHz. They can make gain over 40dB when they are used on IF amplifier. They can oscillate over 100MHz direct. Can you believe that? You can believe that when you make this machine. This machine is a simple single conversion receiver. Oscillator is made with varicap in order to avoid the body effect. This oscillator makes small QRH. But as a radio for SWL, It do not makes any problem.
Mixer convertor is made by dual gate FET. This is a basic usage of circuit of this FET transistor.
IF amplifier has 40dB gain only with 1 transistor. FM detector is called as Wise detector. The characteristic is shown on the fig.3.
The output impedance of Wise detector is very high. Therefore the input impedance of an audio AMP must be very high. Therefore I used a FET , on the front of the audio AMP. This AMP uses a very good output transformer named ST-47. Therefore the frequency characteristic of it is very good. See fig 4! This amplifier has 50mW power output. It is enough for the headphone.
I have jointed the antenna for this gear. I could hear the QSO on my city inside and that of nearby towns.

From: Mohan Mathew[SMTP:lisieux1@sancharnet.in] Sent: Tuesday, July 17, 2001 16:32 To: jf10zl@intio.or.jp Subject: Valuable Doubts! Hello Om.Kazuhiro Sunamura, I am a fellow SWL from India. I am contacting you the first time. I recently came across your home page and the valuable information*s about Ham radio Circuits. Thank you for all circuits and information*s, thanks a lot! I am studying for a graduate degree in Electronics here, I hope I will get the ham license soon(next month itself).I am listening the radio regularly all the bands except the 2meter band. This because I haven't any 2m radio. From your pages I got a 2meter circuit dia. I have some doubts about the circuit components. From the circuit dia its not clear that the converter FET no: clearly, I shall write the doubts for me about the components below.. 1.Converter FET no: 2.IF transistor no: 3.AF amplifier no(1&2): 4.Osc transistor no: 5.varactor diode no: 6.Toroid core no: 7.Is the o/p is an audio transformer?..etc.. please clarify the doubts for me...I think I can CQ you and all from here within 2 months. Can I write further email's regarding your circuits and articles? would you please give me a reply as soon as possible .... Thank you very much.. Mohan Mathew 7/17/01

Dear Mohan These transistors and coils are all famous in Japan. We can easy understand. But for the forliners it is not easy , I understood. I will explain farther more, with answering your question.
1.Converter FET no: 3sk60. Maker Hitachi. Usage VHR,RF amplifier. Pd=330mW. NF=2dB at 100MHz. Power gain=24dB at 200MHz. Please use double gate FET designed to use on the converter of VHF TV!
2.IF transistor no: All IFT are 455KHz AM radio usage. I do not know the number of it.
3.AF amplifier no(1&2): 1st 2sk327: I do not have detailed data now. Sorry! You can use any type of FET here. 2nd:2sc1740: Maker -Rohm. Usage=AF,RF,OSC,SW. Pc=300mW,hfe=120 to 820. FT=180MHz
4.Osc transistor no: 2sc2347: Maker = Toshiba. Usage = mixer. Pc= 250mW. FT=650MHz: Please use Silicone Epitaquisial transistor made to use on VHF mixer for VHF TV.
5.varactor diode no: 1S553: Please use varicap made for FM 80MHz radio converter!
6.Toroid core no: T50-10. Maker = Amidon.
7.Is the o/p is an audio transformer? : Yes. 600: 8 ohms Audio transformer . named as ST47 . Maker = Sansui.

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