Kenwood TS-990S Service Manual

Also see for SP-990: Instruction manual

Contents

TS-990S19CIRCUIT DESCRIPTIONTable 12 BPF rangeBand Filter range135kHz 30~522kHzBC 522kHz~1.705MHz1.8MHz 1.705~2.5MHz3.5MHz 2.5~4.1MHz5MHz 4.1~6.9MHz7MHz 6.9~7.5MHz10MHz7.5~10.5MHz10.5~13.9MHz14MHz 13.9~14.5MHz18MHz14.5~21.5MHz21MHz28MHz 21.5~30.0MHz50MHz (TX) 49.0~54.0MHz50MHz (RX) 30.0~60.0MHz4-2. From the Sub Preamplifier (Q219) to the 2nd IFFrequency (10.695MHz/11.374MHz)The signal from the sub preamplifier (Q219) to the 2ndIF amplifier (Q481) is separated into two paths, SRX-1 andSRX-2, depending on the frequency band (Refer to Table13.). The SRX-1 path is selected if the “L” signal is input toQ958, and the SRX-2 path is selected if the “H” signal is in-put.The signal on the SRX-1 path passes through the LPF forIF trap, is mixed with the SLO1 (12.495MHz to 32.195MHz)in the quad-balanced 1st mixer (Q351 to Q354), and isthen converted to the 1st IF (11.374MHz). The 1st IF signalpasses through the 2-pole MCF(XF351) as a branch circuitto the scope unit (X42-343 A/10) and is applied to the 2nd IFamplifi er 1 (Q481).The SRX-2 path signal passes through the LPF for IFtrap, is mixed with the SLO1 (73.120 to 133.095MHz) in thequad-balanced 1st mixer (Q401 to Q404), and is then con-verted to the 1st IF (73.095MHz). The 1st IF signal passesthrough the 2-pole MCF (XF401) as a branch circuit to thescope unit (X42-343 A/10) and is amplified by approximately12 dB by the 1st IF amplifier (Q408: negative feedback withtransformer type).The amplified signal is mixed with the SLO2 (62.4MHz)in the 2nd mixer (D405 and D406) and is converted to the2nd IF (10.695MHz), and is applied to the 2nd IF amplifier 1(Q481).The 2nd mixer is a passive type that uses a diode, and isa bilateral circuit that performs the frequency conversion ofreceived and transmitted signals.Fig. 17 From the sub preamplifier (Q219) to the 2nd IF frequency (10.695MHz/11.374MHz)FromSub PRE AMPSRX-2LPF~60MHzQ401~404Sub RX 1st Mixer2Q351~354Sub RX 1st Mixer1Q355, 356SLO1 AMP1MCFQ405, 406SLO1 AMP2MCFTXXF35111.374MHzXF40173.095MHzScope unit11.374MHz 73.095MHzLPF+11.374M NOTCH13.174~32.195MHz 73.125~133.095MHzSLO1TXQ408Sub 1st IF AMPD405,406Sub 2nd MixerQ410SLO2 AMPSLO262.4MHzTX11.374MHz10.695MHzToSub 2nd IF AMP1(Q481)SRX-1DIV.DIV.