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		Aug SEP Oct 24 2016 2017 2018
98 captures 17 Jan 1998 - 21 Mar 2020

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Collection: Alexa Crawls

Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period.

TIMESTAMPS

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:[email protected]] Sent: Tuesday, July 17, 2001 16:32 To: [email protected] 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.



５石式１４４ＭＨｚＦＭ受信機
ツーメーターを受信する為に、簡単な受信機を作ってみました。近頃、私はいろいろな用途に２ＳＣ１９０６とか２ＳＣ２３４７とか２３４８とかの、ｆｔが １ＧＨｚを超えるトランジスターを使い始めました。これら、ｆＴが１Ｇを超えるトランジスターで中間周波増幅器、たとえば４５５ｋＨｚのＩＦを作ると、 軽ーク４０ｄＢなんていう増幅率が１石で得られたり、あるいは自励式発信機を作ると１００ＭＨｚを直接発振してくれます。いつもつかっている ２ＳＣ１８１５とか１４７０とかのｆｔが２００ＭＨｚ近辺のトランジスターとは、明らかに格がちがうなーという感じの動作をしてくれます。話は戻って、こ の受信機の構成は、簡単なシングルコンバージョンのスーパーヘテロダインです。局部発信機は２ＳＣ２３４７で、自励式発信機を作り１４４．２９５から １４５．１４５ＭＨｚを直接発振しています。小容量のＦＭ用バリコンを使っても良いのですが、バリキャップを使用してボディーイフェクトを軽減していま す。この局部発振出力は、３ＳＫ６０のミキサーの第二ゲートに入ります。一方第一ゲートにはアンテナからの１４４ＭＨｚのＦＭ信号が入ってくるので、二つ の信号の差の４ ５５ｋＨｚの信号に変換されて出てきます。この４５５ｋＨｚの信号は、セラミックフィルターで濾波された後、２ＳＣ２３４８で１段増幅されて、次のＦＭ検 波器で音声信号にもどされます。このタイプのＦＭ検波器は出力インピーダンスが高いので、低周波増幅器の１段目には入力インピーダンスの高い ＦＥＴ（２ＳＫ３２７）で受けています。最後の、電力増幅器は普通のＡ級増幅器です。このアンプには，ＳＴ47という名前のトランジスター用として有名な ＳＴ−３２よりも倍くらい大きなとてもよい出力トランスを使いました（５年ほど前に、千石さんで１個１００円で売っていたので、みかん箱に入って売ってい た分全て、全部で１５個ほどまとめて買ってしまいました。いわゆる買い占め）．良いトランスを使ったので、低周波増幅器の周波数特性自体がとても良くなり ました。図4を見て下さい。 （アンプの周波数特性なんていっても、いつも、所詮出力トランスの周波数特性を計っているだけです。みもふたも無い話ですが…。）この増幅器は，50mW の出力電力しかありませんが、ヘッドフォンで聴くのには十分な出力です。この機械に空中線をつないだ所、私のすんでいる土浦市の中や，すぐ近くの新治村の ＱＳＯを聞くことができました。


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