The AM is still alive in Japan !


Sept. 10th, 2005 You are the 4359 + counterth visitor
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From left to right, 811A pp Modulator, 813s Final stage, 6146 Excitor

< Receiver >

Old fashon receiver using ST-shape tubes. But available for AM-Streo ! who knows why!?

(1)Starting with Hi-Fi reciever using variable band width IF transformer. It was a story about 30 years ago.

(2)Modified for dressing-up as first stage modification ; I tried to build wood-cabinet in 1998.

(3)Then the 2nd stage modification was " A Road to the AM Stereo Receiver" Here is a modification memo.
It had been growing even after the Stereo, modified again.

(4)and again... Finally, the reciever contains a Mechanical filter for SSB/CW.

< Transmitter >

(1)The first one is my favorit that is operated as an Excitor
This is a nice transmitter using 6146 as final stage, modulated by 6BQ5 p-p. This is the most popular structure of AM transmitter in late 50s - 60s in JA. I'm using this transmitter as excitor for high-power(still middle power in US?) PA.

Circuit diagram

(2)Modulator using 811A p-p.
This is modified from the modulator with 807 p-p, because 807p-p looked not to strong enough for 813 PA.

Circuit diagram



(3)The Staring of this page is the "Final stage" Power Amplifier using RCA 813s.
Running about 120- 140 Watts for carrier output. For this type of PA, we need to use huge parts such as more than 400Watts transmitter, although only 25Watts signal will reach to SSB receiver. This looks AM to be "Mottainai" emission mode in terms of its power efficiency.

Circuit diagram  



Sign wave 800Hz

Psudo-voice wave


July 23rd, 2006, I had a memorial QSO of 2-way AM with JH1MSB in Yokosuka.

Recording: 1 and 2

I was using callsign of "JA1XCT", which is my NEW callsign in JA1 area. I was QRV from Mihama-ku, Chiba city, about 30 miles east of central Tokyo.

The reciver I used was a avobe mentioned RF-1 IF-2 radio receiver with old TRIO RF-amprifier, SM-5. Also I was using 25 meter length three bands(3.5/7/10MHz) Invee antenna about 10meter high.
The sound I recorded was from direct record using microphone.

Sorry, some pages are still left in Japanese.
But I believe circuit diagram would be the common language for us !

Go to my general homepage in JA, Index of Homebrewing