Kenwood AT-440, PS-50, SP-430, PS-430, MB-430, VS-1, YK-88C, YK-88S Fig Frequency configuratio n

TS-440S

CIRCUIT DESCRIPTIO N

1 . Overview

•The TS-440 is a triple conversion type transceiver, incor- porating a general coverage receiver, which uses 45 .0 5 MHz as the first IF, 8 .83 MHz as the second IF, and 45 5 kHz as the third IF .

•The TS-440 is compact, but allows for installation of a n optional internal automatic antenna tuner operating in th e amateur band from 3 .5 MHz to 28 MHz and enables a wide range of antennas to be used .

•The TS-440 also contains a microprocessor-controlled dig- ital PLL circuit which controls frequency in 10 Hz step s using a single crystal oscillator to implement high accura - cy and stable frequency control .

•The TS-440 has the following major features :

(1)Selectable VFOs ; VFO-A and VFO- B

(2)Direct frequency input using a numeric keypad

(3)100-channel memory containing frequency band , and mode information (channel 90 to 99 for split fre -

quency memory)

(4)Memory scan in 10 channel groups and two type s of program scan

(5)RTTY (AFSK) mode availabl e

(6)Squelch circuit operational in all mode s

(7)Dual filters available to improve selectivity and SI N ratio (optional filter required )

(8)IF shift, audio notch, IF filter switching, and RF AT T functions for convenient interference reductio n

(9)Large heat sink and cooling fan (100 W) enabling u p to one-hour continious transmit operatio n

(101 Full and semi break-in circuits for C W

(1 1) External-computer controllable (optional interface re - quired )

(12)Many easy-to-read meter functions such as th e received signal strength (s-meter), transmitter power, SWR, and ALC level .

2 . Frequency Element s

The TS-440 utilizes a triple conversion transmitter an d

receiver .

	V		8 .83MHz	RX MIX3	455KHz	DISCR I
30K	f IN RX MIX 1	45 .05MHz RX MIX2
30MHz , RX								RX OUTPU T
	TX
						DE T
	TX MIX3	TX MIX 2	8 .83MH z	TX MIX I
						SS B		AFS INPU T
						C W	FSK
						FS K
						B .M .
							SS B	MIC INPU T
							AM
	SSB,CWT, AM, FM, FSK						F M
		(FM MOD )				' AMR,FM R
		:45 .O8^-75 .05MH z
	-CW R	:45 .0792-- 75 .0492 MHz				AMT,FMT	: 455KH z
						USB, CW	: 456 .5 KH z
						-LSB,FSK	453 .5KH z

Fig . 1 Frequency configuratio n

The overall frequency configuration of the TS-440 is show n in Figure 1 . The incoming received signal (f, N l is applied to the ANT terminal . This signal is mixed with the local oscilla- tor signal (fvco) in RX MIX 1 to obtain the first IF frequen- cy . This signal is then mixed with the HET Oscillator signa l (fHET) in RX MIX 2, to obtain the 2nd IF frequency . Th e resulting signal is then mixed with the second local oscilla -

tor frequency (f Lo) to obtain the 3rd IF frequency . The sig- nal is then combined with the CAR signal for detection . fiN is expressed mathematically as follows :

fiN = fvco fHEr – fLo fcAlt 1

4