Kenwood-PF810-fpm-sm 维修电路原理图.pdf

.TRIOFUNCTIONPOWERMETERPF-810OPERATING INSTRUCTIONSf.-RadioFans.CN 收音机爱 好者资料库CONTENTSIntroduction. . . . . . . . . . . . . . . . . . . . . . . . . .3Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Specifications. . . . . . . . . . . . . . . . . . . . . . . . . .4Principles ofoperation. . . . . . . . . . . . . . . . . . .5Operating parts. . . . . . . . . . . . . . . . . . . . . . . .7Cautions. . . . . . . . . . . . . . . . . . . . . . . . . . . .9Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . .9Schematic diagram. . . . . . . . . . . . . . . . . . . . . .12Smithchart. . . . . . . . . . . . . . . . . . . . . . . . .13Applications. . . . . . . . . . . . . . . . . . . . . . . . .14-,.INTRODUCTIONThe Function Power Meter ModelPF-810 isa passingtype power/SWRmeter coveringa wide frequency rangeof 1.8MHzto 200MHz. It isa laboratory quality, profes-sional instrument for observing and measuringforwardpower from transmitter to load (antenna) and reflectionpowerfrom 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 powergreater 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 andbusinessuse 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 calibrationtables; calculationsand handling knob of frequencyvariation.*Frequencies are practically flat over the range of 1.8MHz to 200MHz in full scale of meter even in 1.9MHzor 3.5MHz band,thus permittingmeasurementsofvarious functionsin low bands with small power.*Radiant power (RAD) indicator (Pat. pending) to in-dicateforwardpowerminusrefrectionpower,isincluded in the instrument.This is particularly usefulto prevent trouble which might occur during matchingwork, and facilitatesmonitoringand adjustmentsoftransm itter.* Aritennaselectorswitchis self-containedto selecteither of two antennasfor quick QSY. If a dummyload is connectedinstead of antenna, the instrumentfunctions as a terminal type power meter.*Large sized, linear scalefor easy and error-free reading of SWR and power.4Measurement items:SPECIFICATIONSFrequency range:Power measurementrange:Range setting:SWR measurementrange:Minimum power forSWR measurement:Power measurementaccuracy:Residual SWR:Frequency response:Insertion Loss:Type of connector:Input/outputimpedance:Output terminal:Forward power, refrectionpower, radiant power and SWR1.8MHzto 200MHz1Wto 150W5W, 25W and 150W(3 ranges)-+1.0to 10IJ.11WWithin :t10% of full scaleLess than 1.2Within :t 0.25dBLess than 0.5dBUHF type50-ohmTwo (selected by pushbuttonswitch)j,IIIJ-PRINCIPLESof OPERATIONThe Model PF-810 is composed of four major units,a directionalcoupler,a voltage converter,an indicatorand a switching unit; all units except the antenna selectorand the directional coupler, function as a DC circuit.DirectionalcouplerThe directional coupler is used to pick up a very smallpower from the coaxial cable connectedbetween trans-mitterand load by separating forward wave and refrec-tion wave components.The directionalcouplerused in PF-810 consists ofa wide band current transformerT1 and a voltage trans-formerT2, bothemployingtroidalcores as shown inFig. 1.iITXANTRfwd1In Fig. 1, suppose that a currentil flows from TXtoANT, thena reverse currenti2flowsinto thesecondary of the current transformerT2. At this time, acurrenti3is flowing into the primary of the voltagetransformerand, hence, a current i4 (=i2/2) developedfrom 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 voltageappears across Rrefbecause the currents flowing intoRrefin reverse directioneach otherare cancelled,however, a voltage appears across Rfwdbecause thecurrents flowing into Rfwdhave the same directivity.If power is refrectedby ANT, the currenti5con-tinues to flow in the same direction,while the currenti4flows in reverse direction,thus a voltage appearsacross Rref,too.Such an actionis independentoffrequenciesif T1 and T2 each ahve a wide frequencyband.The directionalcouplerof PF-810uses wide bandtransformersconstructedwithtroidalcore and newlydevelopedwindings,topickup thediodedetectedvoltage,proportionalto forwardpower and refrectionpower, from the resistors of Rfwdand Rref.Voltage converterThe voltage converteris used to provide linear read-ings of power on the scale. Without this converter,theDC voltage from the directionalcoupler,which is pro-portionaltoforwardpoweror refrectionpower,isproportionedtothesquarerootof power,thus the5T1i2-i3)-.i4 $ Rrefi5Fig. 1readingson 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 converterisconnectedto boththeforwardpower and refrectionpower terminals.Indicationand selectionThe voltage signal from the voltage converter, whichis proportionalto power, is indicated on the 100,uA DCammeterthroughthefunctionselectorswitch.Thepower range is selected by the range selector resistors.Two sets of voltage converter and selector of the samedesign are providedfor forwardpower and refrectionpower.Thesecan be usedsimultaneously.Being sodesigned, PF-810 is able to indicate radiant power(RAD).Thisis achievedby thedifferentialoperationof thevoltage converters to which forward and refrection wavevoltages applied respectively.In PF-810, two identical circuits are connectedbacktobacktofurtherimprovetheperformanceof thedirectionalcoupler.6TXANT.II4IJ;V.REFV.FWDFig. 2TX.4ANT1()()ANT2.;fig. olockDiagramOPERATING PARTSMeterPower rangeselectorswitchSWRcalibrator.TUOFUNCTIONPOWER METERPF-8I0RANGE (W)FUNeT,REFRAO,15_SWROFF.CALeingused, creating an illusion thattherefrectionpower was very small. However, thiscan be eliminatedby setting the functionswitch to.2.5a:;a:SlO2dAll resistors are 1/4W :t5%, unlessotherwisenoted. The circuit is sub-ject to change withoutnotice forimprovement.CIOO.IF12SIOIS102a-dS103a-dcoANTSELECTORFUNCTIONRANGEC-ANT IOFF05W0 ANT 20 FWD025W0 REF150W0 RAD0 CAL0 SWRSMITHCHARTt.I.I11III1I:111IiI.13APPLICATIONS14DX and local transmissionor quick aSY to other bandswith two antennas000000Transmitteror transceiverTune-up of antenna and TXTransmitteror transceiverNT100ANT 2TX0PF-810PF-810Tune-up of TX or antenna couplerTransmitteror transceiverANT1ANT250-ohm dummy loadc,00Txll 0011ANT2PF-8tOTune-up of TX and antenna couplerTransmitteror transceiverIi-!Antenna couplerANTI_foTXI 0ANT2PF-810Observationandadjustmentof sending waveformswith monitor-scopeTransmitteror transceiverrIr*15