Labels:book | bulletin board | reckoner | sky OCR: KENWOOD SB-974 SERVICE BULLETIN AMATEUR RADIO SUBECT DATE TS. -440S PLI UNLOCK DUE TO PLL 08 08/90 The TS-440S Control unit supplies band informa tion to four circuits in the transce iver The circuits are the rece iver front end Band Pass Filter BPF) the antenna tuner (AT) the transmi tter Low Pass Filter LPF) and the vco ci rcui its the board that are part PLL There are ten rece front end BPFS that are diode swi tched into operat ion one the diodes D4-D23 becomes shorted or leaky the band inf formation two BPFS one time The vol taqe going throuqh the bad diode will loop back to the vco antenna tuner circuit and LPF .rcu The unwanted voltage will then create one OT more of the followi ing PLL unlock (the transce iver only displays decimals) No antenna tuner operat Lon LOW rece ve Sens .tv ...
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