Kenwood-PF810-fpm-sm 电路图 维修手册.pdf

.TRIO FUNCTIONPOWERMETER PF-810 OPERATING INSTRUCTIONS f. . . - RadioFans.CN 收音机爱 好者资料库 CONTENTS Introduction. . . . . . . . . . . . . . . . . . . . . . . . . .3 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Specifications. . . . . . . . . . . . . . . . . . . . . . . . . .4 Principles ofoperation. . . . . . . . . . . . . . . . . . .5 Operating parts. . . . . . . . . . . . . . . . . . . . . . . .7 Cautions. . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Schematic diagram. . . . . . . . . . . . . . . . . . . . . .12 Smithchart. . . . . . . . . . . . . . . . . . . . . . . . .13 Applications. . . . . . . . . . . . . . . . . . . . . . . . .14 -,. INTRODUCTION The Function Power Meter ModelPF-810 isa passing type power/SWRmeter coveringa wide frequency range of 1.8MHzto 200MHz. It isa laboratory quality, profes- sional instrument for observing and measuringforward power from transmitter to load (antenna) and reflection powerfrom loadto transmitter. It is also capable of measuring power actually con- sumed in load (forward power minus reflection power) for convenience of checking the conditions of trans- mitter and load, in addition to measuringSWRat power greater than 1W. Besides being used to monitor the operating condi- tions of transmitter or to adjust filters, matching circuit, etc., it is also used to monitor production lines and businessuse radio stations. 3) RadioFans.CN 收音机爱 好者资料库 FEATURES *Troidal core type directional coupler assuresflat fre- quency response, eliminating the need for calibration tables; calculationsand handling knob of frequency variation. *Frequencies are practically flat over the range of 1.8 MHz to 200MHz in full scale of meter even in 1.9MHz or 3.5MHz band,thus permittingmeasurementsof various functionsin low bands with small power. *Radiant power (RAD) indicator (Pat. pending) to in- dicateforwardpowerminusrefrectionpower,is included in the instrument.This is particularly useful to prevent trouble which might occur during matching work, and facilitatesmonitoringand adjustmentsof transm itter. * Aritennaselectorswitchis self-containedto select either of two antennasfor quick QSY. If a dummy load is connectedinstead of antenna, the instrument functions as a terminal type power meter. *Large sized, linear scalefor easy and error-free read ing of SWR and power. 4 Measurement items: SPECIFICATIONS Frequency range: Power measurement range: Range setting: SWR measurement range: Minimum power for SWR measurement: Power measurement accuracy: Residual SWR: Frequency response: Insertion Loss: Type of connector: Input/output impedance: Output terminal: Forward power, refrection power, radiant power and SWR 1.8MHzto 200MHz 1Wto 150W 5W, 25W and 150W(3 ranges) -+ 1.0to 10 I J. 1 1W Within :t10% of full scale Less than 1.2 Within :t 0.25dB Less than 0.5dB UHF type 50-ohm Two (selected by pushbutton switch) j, I I I J - RadioFans.CN 收音机爱 好者资料库 PRINCIPLESof OPERATION The Model PF-810 is composed of four major units, a directionalcoupler,a voltage converter,an indicator and a switching unit; all units except the antenna selector and the directional coupler, function as a DC circuit. Directionalcoupler The directional coupler is used to pick up a very small power from the coaxial cable connectedbetween trans- mitterand load by separating forward wave and refrec- tion wave components. The directionalcouplerused in PF-810 consists of a wide band current transformerT1 and a voltage trans- formerT2, bothemployingtroidalcores as shown in Fig. 1. iI TX ANT Rfwd 1In Fig. 1, suppose that a currentil flows from TX toANT, thena reverse currenti2flowsinto the secondary of the current transformerT2. At this time, a currenti3is flowing into the primary of the voltage transformerand, hence, a current i4 (=i2/2) developed from i2and a currenti5 developed from i3 to- gether flow into the secondary of the transformer. If these two currents(i4 and i5) are equal, no voltage appears across Rrefbecause the currents flowing into Rrefin reverse directioneach otherare cancelled, however, a voltage appears across Rfwdbecause the currents flowing into Rfwdhave the same directivity. If power is refrectedby ANT, the currenti5con- tinues to flow in the same direction,while the current i4flows in reverse direction,thus a voltage appears across Rref,too.Such an actionis independentof frequenciesif T1 and T2 each ahve a wide frequency band. The directionalcouplerof PF-810uses wide band transformersconstructedwithtroidalcore and newly developedwindings,topickup thediodedetected voltage,proportionalto forwardpower and refrection power, from the resistors of Rfwdand Rref. Voltage converter The voltage converteris used to provide linear read- ings of power on the scale. Without this converter,the DC voltage from the directionalcoupler,which is pro- portionaltoforwardpoweror refrectionpower,is proportionedtothesquarerootof power,thus the 5 T1 i2 -i3 )-. i4 $ Rref i5 Fig. 1 readingson thescale are crowdedwhichcauses dif- ficulty in reading or loss of reading accuracy. The voltage converteruses specially selected diodes, resistors and capacitors.The same type of converteris connectedto boththeforwardpower and refrection power terminals. Indicationand selection The voltage signal from the voltage converter, which is proportionalto power, is indicated on the 100,uA DC ammeterthroughthefunctionselectorswitch.The power range is selected by the range selector resistors. Two sets of voltage converter and selector of the same design are providedfor forwardpower and refrection power.Thesecan be usedsimultaneously.Being so designed, PF-810 is able to indicate radiant power(RAD). Thisis achievedby thedifferentialoperationof the voltage converters to which forward and refrection wave voltages applied respectively. In PF-810, two identical circuits are connectedback tobacktofurtherimprovetheperformanceof the directionalcoupler. 6 TX ANT . I I 4 IJ; V.REF V.FWD Fig. 2 TX .4 ANT1 ()()ANT2 .; fig. olockDiagram OPERATING PARTS Meter Power range selector switch SWR calibrator .TUO FUNCTIONPOWER METERPF-8I0 RANGE (W)FUNeT, REFRAO , 15 _SWR OFF. CALeingused, creating an illusion that therefrectionpower was very small. However, this can be eliminatedby setting the functionswitch to . 2.5 a: ; a: SlO2d All resistors are 1/4W :t5%, unless otherwisenoted. The circuit is sub- ject to change withoutnotice for improvement. CIOO.IF 12 SIOIS102a-dS103a-d coANTSELECTORFUNCTIONRANGE C - ANT IOFF05W 0 ANT 20 FWD 025W 0 REF150W 0 RAD 0 CAL 0 SWR SMITHCHART t. I. I 11 II I 1I :1 11 Ii I. 13 APPLICATIONS 14 DX and local transmission or quick aSY to other bands with two antennas 000 000 Transmitteror transceiver Tune-up of antenna and TX Transmitteror transceiver NT1 00ANT 2 TX0 PF-810 PF-810 Tune-up of TX or antenna coupler Transmitteror transceiver ANT1 ANT2 50-ohm dummy load c, 00 Txll 0011ANT2 PF-8tO Tune-up of TX and antenna coupler Transmitteror transceiver I i- ! Antenna coupler ANTI_fo TXI 0ANT2 PF-810 Observationandadjustmentof sending waveformswith monitor-scope Transmitteror transceiver r I r * 15