2transistor FM radio.----2trfmph.gif
This is a radio in order to receive 80MHz FM. In order to learn the construction of FM transceiver, I made it. See fig1! Second gate of FET oscillates 75 to 85 MHz signal. 80MHz FM signal is injected on the first gate of FET. Therefore two signals is mixed. If signal becomes 6.35MHz. If signal is detected by wize detector. I connected a crystal phone to the output of detector ( A point of the figure ) directly. But I can hear very very weak signal with it. Therefore I made an audio amplifier after that. In this case , the audio amplifier must has it's high impedance input, because the output impedance of wize detector is very high. I could hear the NHK(Japanese govermental broadcasting station),FM broadcasting with 59 by this projects with the antenna of my 50MHz Amateur.

Discription add on 23 Nov 2000:: I am very happy when I receiv the letter and to hear that my home page has re productivity. Thank you . de Kaz::: I show you the letter from Italy.***
From: FERMI Ugo[SMTP:ugo.fermi@fiat.com] Sent: Friday, November 17, 2000 19:01 To: jf10zl@intio.or.jp Subject: Greetings from Italy_____Dear Kazuhiro, This is Ugo, IW1FQG from Italy. I visited your webpage. Your projects are fantastic. I too believe in keeping things simple - and your projects are masterpieces of simplicity. One for all, the 2 transistor FM receiver! Last night I built it, It works !! With my best personal regards, and 73's,

Discription add on 10Dec2000:: My house is located on about 10km from local FM station. Sorry but if you do not live Capital city or suburban side having the FM station like my case, you can not hear any signals with such a poor receiver.

これは,80MHz周波数変調放送(いわゆるFMっていうやつ)を受信する為のラジオです.周波数変調トランシーバーの構造を学ぶために,試作しました.図 1 を見て下さい! FET の第2の ゲートは,75 〜85の メガヘル信号を発振します.受信された80MHz 周波数変調信号は,FET の第一ゲートに注入されています.それでそれらの2個の信号が、ヂュアルゲートFETの内部で混ぜられており、その差の信号が中間周波として出て来ます。中間周波は,6.35MHzです.中間周波信号は直接ワイズ検波器で検波されます.ためしに、直接に、検波器の出力( 図の(A)ポイント) にクリスタルイヤフォーンをつなげてみましたが、もとても弱い信号しか聞こえませんでした.それで,その後にオーディオの増幅器を作りました.この場合,ワイズ検波器の出力インピーダンスがとても高いので,オーディオの増幅器は,高い入力インピーダンスである必要が有ります.ですからオーディオ増幅器はFETにしました。本機に50MHzのダイポールをつなげて、59でNHKのFM放送を聞くことができました.




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