005: 9MHz integrated SSB generator (3 in one)

 1996年に20年ぶりにHFにカムバックした際、手持ちのICOM(IC750A)の変調音がプアだったので外付け変調器として本機を製作した。私の好みはメカニカルフィルタのシャープな音声。三つのモジュレータ(メカフィルはFujitsu 128kc, Collins F250A20, Collins F455Z23C)と、各変調信号を本体へ送り出す9MHzに変換するための局発と共通の(mixer + amp)を一つの箱に作りこんである。マイクの音声増幅段にはグラフィックイコライザもついている。送信中でも瞬時にパチパチ切り替えが可能なため、ラグチューの話題作りには多少貢献したと思う。この三つのメカフィルにはそれぞれの個性があり、どれがいいか一概には言いにくいが、印象深いのは最も帯域の狭いF250A20である。

When coming back to HF after long time in 1996, I found the SSB modulation of ICOM (IC750A) was so poor, that I made this SSB younger stage as an external modulator for ICOM. My favorite tone is clear sound of mechanical filter type of SSB. First of all, I made the three types of modulator (Fujitsu 128kc, Collins F250A20, and Collins F455Z23C). Next, I made the local oscillators and a mixer unit to convert each SSB signal to 9MHz of common IF of ICOM. A graphic equalizer is attached to the microphone amplifier. As I could instantaneously switch the modulator unit while even transmitting, I think it somewhat contributed to making of the topics in the ragchew. I hesitate to say which one is good, because they have a peculiar characteristic in each type of mechanical filter respectively. The Collins F250A20, the band width is the narrowest but it impressed me strong.
(making was in 1996)




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