50MHzAM40mW Handy transceiver

I wanted to use a pair of handy transceiver to use holiday. AM is good mode to use such a purpose because I am an OM. Therefore mode was decided as AM. I decided to make it with a single conversion. Therefore I need a crystal that can oscillate a transmitting frequency directly. On the catalogue of the parts shop I could find 50.55MHz. Transmitting frequency was decided such a way. I want to use a 455kHz IFT for the IF transformer. On the catalogue of the parts shop I could find 50.10MHz. 455kHz IFT must be able to tune for 450kHz. I wanted to make this transceivers with the " surface mount construction" ( You will use another word for the same meaning. It is not English but Japanese, HiHi. ) But in Japan on the summer of 2000 , we can not buy the parts for surface mount construction even on the AKIHABARA city. Therefore I decided to make this (these) with conventional configuration. Rear side is print pattern drown by writing brush. Upper side (parts side) is all ground pattern. Case is lunch box sold by 288 Yens. I used 5cm square shape 3mm thick 8 ohms speaker. I feel you can use more normal 8cm dynamic speaker, if you have more space. I did 200m distance QSO with a pare of these same units. I show you the print pattern. But you must re draw it in order to match your parts. Please not to send me the E mail that " Send me the parts match for your project!". I am not parts dealer. But I will send you this transceiver itself if can use my gears to educate boys and girls.

Description add on 30Aug2000: As you can understand all this gear depends on the technique about 20 years ago. You can find the similar projection on the book about 20 years ago. I tried to make more modern construction. I will explain about my trial.
1. " Small thin speaker has poor efficiency." We can get 4mm thick speaker on the Akihabara electric shop in Japan. But such speakers has 70dB efficiency to produce the sound from the electric power. How to measure the efficiancy of the speaker isdecided in the Japanese industrial standard"JIS". 70dB efficiency is 10dB worse than the normal small 5cm speaker used on the pocket radio. I changed the speaker from 5cm diameter 4mm thick type to 6.6cm normal dynamic type. I can operate very easily with it with better feeling. Therefore I think I had better to make speaker hole on the print board to use conventional type speaker with more better space efficiency.
2. "Space efficiency will achieve over 50% except by using special order parts and special order made case." In order to reduce the capacity of the case with the same circuits, we must use special parts as special antenna connector, special power switch, special transmitting switch. And we must make the case with ourselves to make it as just size.
3. " Special parts reduces the re productivity of listener." I want to use more small push switch for transmitting switch. I searched (looked for) it in the electric shops. But I could not find it. Push switch is decided its size in Japanese industrial standard. Therefore I can not find any other size of them. On the other hand I could find many size of speakers. In Japan speakers are classified with its diametric size. But I can find many types of 5cm speakers which has many size of its driving magnet. If I make the case and print board to just to my speaker , you will be not able to use it.
4."Mix mount technology looks no good." I can find some type of surface mount type (chip: I like Chips like as star treck) capacitors in the shop. But 15pico farads can not be found. I must use conventional type capacitor for 15pico farads . I could find many surface mount resisters. But I could not find 0.5 ohms. I could find the 47micro farads surface chemical capacitor. But I could not find 100 micro farads. I will not get good looks for such a print board that has many types of parts on the both side. """This page will be continued!!!!!

Description add on 2 Sep 2000: Once time I made a pair of transceiver with plastic (poliethiren) lunch box. But it is not see through. I want to show a printed board in the case to my friends on my local meeting. Therefore I tried to make a case with clear plastic plate. Once , the plate has broken when I made a hole on it. My friend Mr.Usui JJ1ILR tought me a hint that , " Make small hole once ! Use thick drill one by one!" Using this method, I completed the new case. I want to teach you some another know how to make case with achril plastic ( sorry my dictionary do not know the spell of it).
1. How to make a hole.
1-1. If you want to make a hole more than 2.5mm diameter , make 2.5mm hole once! After that you can make wider the hole with using 0.5mm thicker (fat) drill.
1-2. Use a drill for iron! Not use a drill for wood!
1-3. The maximum diameter of the hole made by drill is 5.0mm. If you want to make bigger hole, you should use rasp or sand paper. (( My family name "SUNAMURA" means " Sand Village" ))
1-4. Lay wooden plate directly under position of the drill anytime! On the timing of the drill go through the plastic plate, the big shock happens. This shock is a main reason to break the plate. In order to avoid this shock, lay wooden plate directly under position of the drill anytime!
2. How to bend an achril plastic plate.
2-1. Buy about 16mm diameter iron bar! Heat it with gas cooking range!
2-2. Wait until 2 "minuten"! Extinguish the fire! Put the plastic plate on the bar! Wait 10 seconds! Bend the plate be 90 degree !
2-3. Cool down with water while put it on the edge of 90 degree edge of wodden bar.
2-4. Diameter of inner side after bending is same as the diameter of before bending. Diameter of outer side after bending is bigger than the diameter of before bending. When you bend the plate, the outer side of the plate is extended.
2-5. Anyway try to bend your small useless plastic plate! Make sure about the diameter and radios after bend with yourself!
3-1. We can not get a screw with our wanted size. In Japanese " Sunday constructor shop" , we can get 5mm pitch screws. The word "Sunday constructor" means the man who make construction only in Sunday. On another days he will works as a secretary or post man or some any another kind of job. " Sunday constructor shop"is called also as "Do it yourself shop" in Japan.
3-2. Be care! The length of the bolt may not means the length of the screw. It may indicates the whole length. The screw I got "M3*35mm" has only 33mm of its screw length. ( I can use the EMCO multi purpose small machine , on my fathers house. It can be used as a grinder. If you have a grinder ,you can adjust the length of the bolt as you like.

Description add on 16 Sep 2000: In this week, I made a new transceiver with a chip parts. It is smaller than old two models. I decided to call the new one as a third version. I will talk you what I felt while I make this third version.
1." With chip parts and order made case , the capacity of the hole assembly can be reduced for half of the discreet and sold lunch box." The first version was made of discreet parts and sold lunch box. It used the 6.6 cm dynamic speaker. The size of the case was , 140(width)* 95(length)*45(thick). The capacity of it was 600cm2. The second version was made of discreet parts and plastic (achril) designed case. It used the 5.0 cm diameter 4mm thick super thin type speaker. The size of the case was , 130(width)* 85(length)*32(thick). The capacity of it was 350cm2. The third version was made of chip and discreet parts and designed case. It used the 6.6 cm dynamic speaker. The size of the case was , 120(width)* 75(length)*30(thick). The capacity of it was 270cm2. The second version uses a special speaker. The third version has half capacity of the first version.
2. " AGC (automatic gain control system) is effective." I made the third version out of (less) an AGC system. I made QSO with the third version and the first version. When I made QSO with the distance over 50m, the two assembly act the same performances. But when I made QSO with in my house with the different room, the first version can generate the voice sound as a understandable voice. But then, the third version generates only loudly rough un-understandable sound. I checked the AGC voltage of the first version. Vagc of no signal is 0V. Vagc of 1m distance is -0.73V. Vagc of 5m distance is -0.30V. Vagc of 10m distance is -0.20V. Original self bias voltage of the RF amplifier FET is -0.57V. Yes, on the house, the double bias voltage drives the amplifier than the far away. Sorry I can not calculate the correct decibels. I can say that the AGC extends the cover aria of the transceiver for nearer side than that of AGC less.
3." FET can be used as up side down." Look the figure 3-5! I wanted to use the FET with the opposite direction of its drain and souse for better design of print board. I used it up side down. But then leg of the FET becomes far from the print board. It is difficult to solder it. I bend the leg (lead) of the FET. Care not to break the leg! If you are professional, you do not use such a way. This method can be used only by amateur radio hand maker.
4."Chip parts can be got on the SUZUSYO shop in AKIHABARA city." I walked and looked for the chip parts on AKIHABARA city for three hours. Only in the SUZUSYO shop ,I could get the chip FET and chip transistors. In third version I used 2sk210 and 2sc2713 instead of 2sk241 and 2sc1906. Chip resisters and chip capacitors are got from the junk (broken) print board of some (unknown) digital systems.
5."FET must be lain on the bottom of the coil case." Look figure 3-1! Even if you use the chip parts, you can not save so many size. You can save the size ,if you put the FET chip on the bottom of the coil case, like fig 3-2. In order to put the FET on the bottom of it, the coil must be 10mm square size. We can get 7mm *7mm coil. But it is too small, is not it?
6." Use turtle washer to fix the speaker!" The washer made and sold to fix the waving board of the construction material is called an turtle washer in Japan. It may not be English. Hi Hi. Look the figure 3-3!
7."A 1.5mm thick plastic board is enough to use as a case." On the first version I used 2mm thick board. On the third version I used the 1.5mm board. 1.5mm is easy to bend. Enough hardness.
8."Use 45mm diameter whetstone with hand drill to shorten the screw! ": You can fix a vice (vise) on the desk. You can fix the hand drill on the vice. You can fix the 45mm diameter whetstone on the chuck of the hand drill. Make your daughter to drive the hand drill! You can put the screw on the whetstone. You will need 10 minutes to reduce the length for 2mm of M3 screw.
9."About next trial". In order to make smaller transceiver than third version, I must get a technology of photograph print pattern. In order to look for small sized good speaker I must make the speaker evaluating system. These new technologies are hard to get. I decided to stop this project by myself now.

2sk241. Maker =Toshiba, Usage = FM/VHF RF, Type =Mos, N channel, Vmax =20V, Idss=1.5mA,
gm=10mS,Crs=0.035pF,PG=28dBtyp at 100MHz.......
2sk210. Maker =Toshiba, Usage = VHF RF, Type =J, N channel, Vmax =18V, Idss=1.0mA,
gm=7mS,Crs=0.65pF,PG=24dBtyp at 100MHz.....
2sc1906,Maker= Hitachi, Usage = VHF A/MIX/OSC, type=NPN, Vmax =30V, Pcmax=300mW,
hfe=from 40to250,ft=600Hz,Cob=2pF,PG=18dB at 200MHz......
2sc2713,Maker= Toshiba, Usage = LF LN A, type=NPN, Vmax =120V, Pcmax=150mW,
hfe=from 200 to 700,ft=100Hz,Cob=3pF,PG=10dB at 1KHz


50m40mw3.bmp.....Drowing of print pattern. I drew it with 2/1 size.:::::1、2号機の基板設計図(作図は2/1倍)

50m40mw4.bmp: I like to play with PLAYSTATION........Print pattern of Version 1 and 2.....1、2号機の基板(共通)

50m40mw5.bmp....hand made transceiver with 2 dollers of Tapperware....Version1::::1号機

50mh40mwph113.gif....hand made transceiver with my hand made plastic case....Version2::::2号機


50m40mw3gouex.gif......explanation how to make version3 ....3号機製作に関する説明図面

近距離の連絡用にトランシーバーがほしくなり、作ってみました。以前も、50MHzSSBのハンディーをつくりましたが、SSBは、QRHに対応して周波数を微調整しなければならないので、近距離連絡用としてはむいていない事がわかっています。そこでモードはAMにしました。周波数は、サトー電気の通信販売で入手できる周波数という事で、ほとんど考慮の余地がなく50.55MHz送信、50.100MHz受信、中間周波は450kHZ(455kHzの中波用IFTでカバー)ときまってしまいました。ダブルスーパーやプリミックスならいろいろ考えられましたでしょうが、ハンディーですので、シングルスーパーとしました。面実装をやって小さく作ってみようとも考えましたが、面実装のICは我々アマチュアの入手できる範囲ではまだ種類がすくなく、適当なICがみつからなかったのと、せっかくICを面実装にしてもIFTが面実装でないので、あまり小さくならなそうでしたので、コンベンショナルにしました。ただし、今回はできるだけ基板上のジャンパー線をなくしてすっきりまとめようと思いました。写真でおわかりの様に、裏面にパターン、表面(部品面)はベタ アースとして動作の安定を図っています。(というか両面にパターンを作成するのはちょっと大変ですから。HIHI。)回路は、個人的にも極めて実績の在る回路の寄せ集めです。受信は、高周波1段増幅付きのシングルスーパーです。中間周波はモトローラーの中間周波増幅専用ICであるMC1350pを使用しています。低周波増幅はLM386を使って利得を60dB(今回の調整後の実測地)得るもので、私の他のページに詳しく説明してあります。送信は3段の強電力変調で、変調増幅器は受信用の低周波増幅器と共用です。ケースは実験用の仮のケースで、一個288円のおかず入れです(後でこれを1号機と命名)。これでだいたい200mくらいの見通しの交信ができました。スピーカーは5cm角型で厚さ3mmの厚さの超うす型ですが、ケースに余裕があるなら、あまり無理せず、普通の8cmや10cmスピーカーのほうがずっと効率が良くよろしいとおもいます。いちおうプリントパターンを示しておきましたが、部品にあわせて御自分でひきなおしてください。私は、トレーシングペーパーの方眼紙に2倍で表面から描いて、裏返しにして50%縮小コピーをとって、それを基板に 乗せて上から「千枚通し」でつついてへこみをつけて、このへこみを頼りに、パターンを手書きしました。パターンを書くには絵筆にマジックインキの補充液を着けて書きました。

1.「小さなスピーカーほど効率が悪い。」昔の丸い頭のスピーカを、基板の中に穴を開けてもぐりこませる業(わざ)は今でも有効。」:どうもトランシーバーの感度が悪いので、厚さ3mmの超薄型スピーカーを、普通の円筒形の頭の5cmスピーカーに換えてみたらずいぶんと感度が上がりました。昨日(28Aug2000)アキバで物色していたら、在るお店の3mm厚さスピーカーの正札に70dBと性能記載がありました。70dBといえば、車載の10cmスピーカーの90dB,ラジオ用5cmスピーカーの80dBと比べて、相当に効率が悪い。車載の10cmスピーカーはハンディーには使えませんからそれと比べてみてもしょうがないとして、ラジオ用5cmスピーカーの80dBと比べてさらに10dB悪い。さらに、電気を音に換える効率だけでなく、音を電気に換える効率も悪そうです。そういった訳で、ハンディートランシーバーにも出来るだけ大きなスピーカーを使うのが良さそうです。そのために、ポケットラジオ等で、昔からやられている様に、基板に穴を開けて、そこにスピーカーを潜り込ませるレイアウトは、性能を確保しながら、全体の大きさをおさえるのに極めて 有効な事が判明しました。


2.「AGCは有った方が良い」:今回は、少しでも小さくしたかったので、AGC回路を省略してみました。AGC有りの1号機と、AGC無しの3号機でQSOしてみるとやはりAGCのありがたみが分かる結果となりました。50m以上離れてしまえば、どちらでも同じ感じで交信できるのですが、家の中で、1階と3階とか、防音になっているピアノ室と居間で交信してみると、つまり直接声が聞こえないが距離的には5mくらいで交信してみると、1号機ではちゃんと聞き取れるのに、3号機ではがさごそいっているだけで、内容が聞き取れません。振り返って、1号機のAGC電圧を、交信距離とのデータを取ってみました。無信号時AGC電圧=0V。1m距離での受信時のAGC電圧は−0.73V。5m距離での受信時のAGC電圧は−0.30V。10m距離での受信時のAGC電圧は−0.20V。無信号時の高周波増幅段の自己バイアス電圧は0.57V。つまり、近距離で交信した場合には、自己バイアスの倍のバイアスがかかているのですから、正確に何デシベルきいているかは判りませんが、相当に深くバイアスが掛かっている訳で、AGCがうまく働いています。しか し、先ほどもいいましたが50mも離れてしまえば、AGCはいりません。もともと数mで交信する必要は無いのですから、実用的にはほんとに必要なのかは別問題でしょう。

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