Amateur xov tooj cua receiver: yam ntxwv

Amateur mloog xov tooj cua kav hlau txais xov uas tau txais pua pua txhiab tus xov tooj cua Pib ntsais koj teeb ib txhij. Lawv zaus tej zaum yuav txawv nyob ntawm seb cov kis rau ntev, nruab nrab, luv luv, ultra luv luv tsis thiab TV bands. Nruab nrab ntawm lawv khiav lag luam pib xyaum ua, tsoom fwv, coj mus muag marine thiab lwm yam noj. Lub amplitudes ntawm tus ntsais teeb noj mus rau lub receiver kav hlau txais xov tswv yim, thaj tsam li ntawm tsawg tshaj li 1 MV rau ntau millivolts. Amateur mloog xov tooj cua hu tshwm sim nyob rau theem ntawm ib tug ob peb Microvolts. Sij hawm ntawm pib xyaum ua receiver ob: xaiv, amplification, thiab demodulation ntawm yam xov tooj cua teeb liab, thiab ntsuam xyuas cov tag nrho cov lwm leej lwm tus. Amateur mloog xov tooj cua txais txiaj ntsim zoo muaj yog nyias los yog raws li ib feem ntawm cov transceiver.

Lub ntsiab Cheebtsam ntawm lub receiver

Ham xov tooj cua receivers yuav tsum tau txais kev tsis tshua muaj zog Pib ntsais koj teeb, cais lawv los ntawm lub suab nrov thiab high-zog noj, yeej ib txwm tam sim no nyob rau hauv cov huab cua. Yog li rau lawv cov tuav thiab demodulation yuav tsum tau txaus stability. Zuag qhia tag nrho kev kawm (thiab tus nqi) ntawm lub xov tooj cua nyob rau lub Translation, selectivity thiab stability. Muaj lwm yam tseem ceeb hais txog kev kawm ntawm lub ntaus ntawv. Cov muaj xws li cov kev pab them nqi thiab nyeem ntawv zaus, demodulation hom los yog cov nrhiav kom tau ntawm LF, MF, HF, VHF radios, fais fab yuav tsum. Thaum receivers yog distinguished los ntawm, tag nrho cov complexity thiab kev kawm ntawv pab txhawb nqa 4 lub ntsiab functions: txais tos, selectivity, demodulation thiab tu tub tu kiv. Ib txhia kuj muaj xws li enhancers rau kom lub teeb liab qib tau qhov tseem ceeb.

txais tos

Nws yog ib lub peev xwm ntawm lub receiver lis tsis muaj zog Pib ntsais koj teeb sau los ntawm kav hlau txais xov. Rau xov tooj cua, qhov no feature yog feem ntau txuam nrog rhiab heev. Feem ntau cov qauv muaj ob peb cascades ntawm amplification yuav tsum tau rau koj ntxiv kom lub teeb liab hwj chim los ntawm Microvolts rau volts. Yog li, lub zuag qhia tag nrho receiver nce yuav mus txog qhov kev txiav txim ntawm ib lab mus rau ib.

Beginners hams pab tau paub hais tias cov receiver rhiab heev yog cuam tshuam los ntawm hluav taws xob nrov generated nyob rau hauv lub kav hlau txais xov Circuit Court thiab lub ntaus ntawv, tshwj xeeb tshaj yog nyob rau hauv lub tswv yim thiab RF modules. Lawv tshwm sim thaum lub sij hawm thermal excitation neeg xyuas pib molecules thiab amplifier Cheebtsam xws li transistors thiab hlab. Nyob rau hauv kev, hluav taws xob nrov yog zaus nyob thiab tsub kom nrog kub thiab bandwidth.

Tej suab nrov tam sim no nyob rau hauv lub receiver kav hlau txais xov terminals yog amplified nrog rau cov tau txais lub teeb liab. Yog li, muaj ib tug txwv ntawm rhiab heev ntawm lub receiver. Feem ntau cov niaj hnub ua qauv yuav tau txais 1 MV los yog tsawg dua. Muaj ntau specifications txhais no feature nyob rau hauv Microvolts mus rau 10 dB. Piv txwv li, qhov rhiab heev ntawm 0.5 MV mus rau 10 dB txhais tau tias lub amplitude suab nrov generated nyob rau hauv lub receiver los ntawm kwv yees li 10 dB hauv qab no lub teeb liab ntawm 0.5 MV. Nyob rau hauv lwm yam lus, lub receiver suab nrov theem yog hais txog 0,16 MV. Tej teeb liab hauv qab no tus nqi yuav sib tshooj thiab lawv yuav tsis tau audible nyob rau hauv cov lus.

Thaum frequencies ntawm 20-30 MHz lwm cov suab nrov (atmospheric thiab tus txiv neej-ua) feem ntau yog ntau dua sab hauv cuam. Feem ntau cov receivers muaj txaus rhiab heev rau lub teeb liab ua nyob rau hauv no ntau zaus.

selectivity

Qhov no muaj peev xwm qhib cov receiver rau cov kev kawm lub teeb liab thiab tsis lees paub leej twg kiag. Nyob rau hauv receivers siv high-Q LC-lim rau dua xwb ib tug nqaim bandwidth. Yog li, lub receiver bandwidth yog ib qho tseem ceeb los mus tshem tawm pliaj Pib ntsais koj teeb. Selectivity ntau DV-receivers ntawm qhov kev txiav txim ntawm ob peb puas Hertz. Qhov no yog txaus rau cov nroj tsuag tawm feem ntau ntawm cov Pib ntsais koj teeb uas yog nyob ze rau qhov kev khiav hauj lwm zaus. Tag nrho cov pib xyaum ua xov tooj cua receivers HF thiab SV yog hom twg yuav tsum tau xim txog 2500 Hz rau pib xyaum ua lub suab txais tos. Muaj ntau receivers thiab transceivers ET / switchable HF cov ntxaij lim dej yuav siv los muab zoo txais tos lub teeb liab ntawm txhua yam.

Demodulation, los yog nrhiav kom tau

Qhov no txoj kev ntawm kev sib cais ntawm LF-tivthaiv (suab) los ntawm cov khoom modulated cab kuj teeb liab. Lub demodulation circuits siv transistors los yog lub teeb. Lub ob feem ntau hom detectors siv nyob rau hauv RF receivers, - ib tug diode rau LW thiab MW, thiab LW zoo tagnrho tov khoom los yog HF.

playback

Qhov kawg cov txheej txheem yog mus hloov lub txais tos lub teeb liab kuaj nyob rau hauv cov suab pub rau cov lus qhia los yog headphones. Feem ntau, amplification ntawm ib tug tsis muaj zog tso zis ntawm lub ntes theem yog siv nrog high efficiency. suab amplifier tso zis no ces noj mus rau ib tug hais lus los yog earphone rau me nyuam.

Feem ntau cov amateur xov tooj cua receivers muaj ib tug nrog hais lus thiab ib tug lub mloog pob ntseg tso zis nkaus. Tej yam yooj yim ib theem suab amplifier haum rau siv nrog headphones. Rau cov lus qhia feem ntau yog yuav tsum tau 2 los yog 3-theem suab amplifier.

yooj yim receivers

Tus thawj receivers rau xov tooj cua yog ib tug yooj yim ntaus ntawv uas muaj ib qho oscillatory Circuit Court, kristallodetektora thiab headphones. Lawv yuav muab ib tug xov tooj cua chaw nres tsheb. Txawm li cas los, tus siv lead ua ntes tsis tau kom raug demodulate tus ntsais teeb LW los yog SW. Tsis tas li ntawd, rhiab heev thiab selectivity ntawm xws li ib tug tswvyim yog tsis txaus rau pib xyaum ua hauj lwm. Kom lawv los ntawm kev ntxiv lub suab amplifier mus rau lub tso zis ntawm lub ntes.

Xov tooj cua direct amplification

Lub rhiab heev thiab selectivity yuav kho los ntawm kev ntxiv ib los yog ntau tshaj theem. Qhov no hom ntawm ntaus ntawv yog hu ua ib tug tib neeg receiver nce. Muaj ntau coj mus muag SW Receivers '20s thiab' 30s. Peb siv cov nram qab no cov tswvyim. Ib txhia ntawm lawv muaj nce theem 2-4 mus muab tau cov kev kawm rhiab heev thiab selectivity.

direct hloov dua siab tshiab receiver

Qhov no yog ib tug yooj yooj yim thiab nrov mus kom ze rau uas tau txais thiab HF ET. Lub tswv yim teeb liab yog noj mus rau ib tug ntes nrog rau ib tug RF generator. Xeem ob peb zaus saum toj no (los yog hauv qab no) tus thawj yuav tsum tau txais lub plawv dhia. Piv txwv li, yog hais tias tus tswv yim 7155,0 kHz, thiab cov RF generator yog configured 7155,4 kHz, ces nws nyob rau hauv lub ntes tsim ib lub suab ntawm 400 Hz. Xeem los nyob rau hauv ib tug high-power los ntawm ib tug nqaim heev audio lim. Selectivity nyob rau hauv no hom ntawm receiver yog tiav ntawm LC-oscillatory circuits thiab ib lub suab ntes nyob rau hauv pem hauv ntej ntawm lub taub lim ntawm cov ntes thiab lub suab amplifier.

superheterodyne

Tsim nyob rau hauv thaum ntxov 1930s nyob rau hauv thiaj li yuav tshem tawm feem ntau ntawm cov teeb meem kev nyuaj siab los ntawm cov laus hom ntawm pib xyaum ua xov tooj cua receivers. Niaj hnub no superheterodyne receiver yog siv nyob rau hauv txhua hom ntawm xov tooj cua cov kev pab cuam, xws li kev pib xyaum ua xov tooj cua, coj mus muag, raws li tau zoo raws li amplitude thiab zaus tes taws los piav thiab TV. Lub ntsiab sib txawv ntawm qhov ncaj-amplification receivers yog hloov cov khoom RF teeb liab mus rau ib nrab (YOG).

RF amplifier

Comprise LC-circuits uas muab ib co selectivity thiab tsawg amplification ntawm ib yam kev zaus. Lub RF amplifier kuj muab ob tug cov kev pab nyob rau hauv ib tug superheterodyne receiver. Firstly, nws txiag tus tov khoom theem thiab lub zos oscillator Circuit Court mus rau lub kav hlau txais xov. Rau xov tooj cua, lub zoo dua cov lus dag nyob rau hauv lub fact tias cov attenuated undesired Pib ntsais koj teeb uas nws zaus yog ob zaug raws li high school raws li xav.

generator

Yuav tsum tau mus tsim ib tug sinusoidal teeb liab nrog rau qhov amplitude, uas nws zaus raws ntawm lub tswv yim cov cab kuj los ntawm ib tug nqi sib npaug zos rau cov HAIS TIAS. Generator tsim deeg, uas yuav ua tau zaus yog saum toj no los yog hauv qab no cov cab kuj. Qhov no kev xaiv yog txiav txim los ntawm lub bandwidth yuav tsum thiab configuring RF. Feem ntau ntawm tej cov rooj sib txoos nyob rau hauv lub NE-receivers thiab qis amateur band VHF-receiver generating ib lub tswv yim zaus saum toj no cov cab kuj.

tov khoom

Lub hom phiaj ntawm qhov no unit yog mus hloov lub zaus ntawm cov khoom cab kuj teeb liab mus rau ib tug YOG-amplifier zaus. Tov Khoom 4 outputs lub ntsiab tso zis teeb liab los ntawm 2 lub tswv yim: f _1, f _2, f ₁ + f _2, f ₁ -f _2. Nyob rau hauv ib tug superheterodyne receiver yog tsuas yog siv yog lawv zaum los yog sib txawv. Lwm cov yuav ua cuam tshuam, yog hais tias tsim nyog ntsuas tsis npaum li cas.

YOG amplifier

Cov yam ntxwv ntawm cov HAIS TIAS amplifier nyob rau hauv ib tug superheterodyne receiver yog zoo tshaj plaws piav nyob rau hauv cov nqe lus ntawm koj qhov nce (CG) thiab selectivity. Feem ntau hais lus, cov tsis yog txiav txim los ntawm lub YOG amplifier. Lub selectivity ntawm lub YOG amplifier yuav sib npaug zos rau cov dav ntawm cov khoom modulated RF teeb liab band. Yog hais tias nws yog, ces tej uas nyob ib sab zaus yog raug hla lawm thiab ua cuam. Nyob rau lwm cov tes, yog hais tias tus selectivity yog ib yam nkaus thiab nqaim, ib co sab bands yog txiav. Qhov no ua rau ib tug tsis txhais ntawm lub suab los ntawm cov lus qhia los yog headphones.

Lub optimum luv luv-receiver bandwidth yog 2300-2500 Hz. Txawm tias ib co ntawm lub siab dua sab bands txuam nrog hais lus Pib ntsais koj teeb tshaj 2,500 Hz, lawv tsis tsis ho muaj kev cuam tshuam lub suab los yog cov ntaub ntawv kis tau los ntawm cov neeg teb xov tooj. 400-500 Hz txaus selectivity rau ET. Qhov no nqaim band pab los tsis lees txais tej lub teeb liab ntawm qhov uas nyob ib sab zaus, uas tej zaum yuav cuam tshuam nrog kev txais tos. Nyob rau hauv pib xyaum ua radios, tus nqi ntawm uas saum toj no yog siv ob los yog ntau tshaj cascade YOG amplification nrog ib tug heev crystalline los yog ua ntej cov neeg kho tshuab lim. Nrog rau qhov no arrangement, nruab nrab ntawm lub blocks siv LC-circuits thiab inverter converters.

Xaiv ntawm lub intermediate zaus yog txiav txim los ntawm ob peb yam tseem ceeb, uas muaj xws li: enhanced selectivity thiab teeb liab hluav. Rau cov tsawg zaus bands (80 thiab 40 m) inverter siv nyob rau hauv ntau niaj hnub pib xyaum ua xov tooj cua receivers yog 455 kHz. YOG amplifiers yuav muab yav tom ntej nce thiab selectivity ntawm 400-2500 Hz.

Detectors thiab dhia oscillators

Kom paub tias, los yog demodulation, yog txhais raws li tus txheej txheem faib Suab zaus Cheebtsam ntawm lub modulated cab kuj teeb liab. Detectors nyob rau hauv superheterodyne receivers, kuj hu ua theem nrab, tab sis thawj tov khoom yog ib tug node.

Tsis Siv Neeg tau tswj

Lub hom phiaj ntawm lub AGC chav tsev yog kom muaj ib qhov zis teeb liab theem, txawm hloov nyob rau hauv lub tswv yim. Xov tooj cua tsis propagating los ntawm cov ionosphere, ces tsis muaj zog txaus, ces augmented los ntawm lub phenomenon hu ua fading. Qhov no ua rau ib tug kev hloov nyob rau hauv lub txais tos theem ntawm cov kav hlau txais xov chaw nres nkoj nyob rau hauv ib tug ntau ntawm cov qhov tseem ceeb. Txij li thaum lub rectified voltage teeb liab xwm yeem mus rau amplitude ntawm tus tau txais ntes, ib feem ntawm nws yuav siv tau rau koj qhov nce tswj. Rau receivers ua hauj lwm lub teeb los yog npn-transistors ntawm cov ntshav ua ntej lub ntes, los txo cov KU tsis zoo voltage yog thov. Amplifiers thiab mixers, siv pnp-transistors yuav tsum tau ib tug zoo voltage.

Ib txhia pib xyaum ua xov tooj cua receivers, tshwj xeeb tshaj yog qhov zoo tshaj plaws transistor kom muaj ib tug amplifier nrog automatic nce tswj rau ntau dua tswj cov yam ntxwv ntawm tus ntaus ntawv. Tsis Siv Neeg hloov yuav muaj ntau lub sij hawm constants rau ntau hom kev Pib ntsais koj teeb. Lub sij hawm tas li txiav txim lub duration ntawm lub tswj tom qab txiav ntawm txhais lus. Piv txwv li, thaum lub sij hawm cov Team sib ntawm cov nqe lus HF receiver rau tam sim ntawd rov pib dua tag nrho nce, ua ib tug annoying audible suab nrov.

Ntsuas ntawm lub teeb liab lub zog

Nyob rau hauv ib co receivers, thiab transceivers muab ib qho taw qhia seb txheeb ze zog ntawm cov tshaj tawm hauv xov. Feem ntau cov rectified feem ntawm lub YOG teeb liab los ntawm lub ntes yog noj mus rau ib tug micro- los yog milliammeter. Yog hais tias lub receiver muaj ib tug AGC amplifier, qhov no unit yuav kuj yuav siv los tswj cov zaub. Feem ntau ntawm cov ntsuas pab kiag li lawm yog kom nyob rau hauv S-units (1 mus rau 9) uas yog kwv yees li 6 dB hloov nyob rau hauv tau txais lub teeb liab lub hwj chim. Qhov nruab nrab nyeem ntawv los yog S-9 yog siv los qhia rau cov theem ntawm 50 MV. Lub sab sauv ib nrab ntawm S-meter scale kom nyob rau hauv decibels saum toj no S-9, feem ntau li 60 dB. Qhov no txhais tau tias lub hwj chim ntawm tus tau txais lub teeb liab ntawm 60 dB saum toj no 50 uv thiab sib npaug zos rau 50 MV.

Lub ntsuas no yog qhov tsis tshua muaj tseeb, vim hais tias nws ua hauj lwm yog los ntawm ntau yam tseem ceeb. Txawm li cas los, nws yog heev pab tau nyob rau hauv kev txiav txim tus kwv tij kev siv ntawm cov khoom Pib ntsais koj teeb, raws li zoo raws li kev kuaj los yog teem tuaj rau receiver. Nyob rau hauv muaj ntau yam transceivers qhia ua hauj lwm pab mus tso saib tus txheej xwm ntawm lub ntaus ntawv nta, xws li zaum kawg RF amplifier tam sim no thiab ib tug RF tso zis ntau zog.

Cuam thiab kev txwv

Beginners hams pab tau rau koj paub tias tej receiver tej zaum yuav muaj teeb meem nrog lub txais tos vim hais tias ntawm peb yam tseem ceeb: nrog thiab lwm cov suab nrov thiab teeb liab ntsais ntsais koj teeb. Sab nraud RF cuam, nyob rau hauv particular hauv qab no 20 MHz, ntau ntau dua li cov nyob hauv sawv daws yuav. Tsuas yog ntau dua frequencies receiver ntshav roos ib tug kev hem thawj rau lub muaj zog heev Pib ntsais koj teeb. Feem ntau ntawm nrov generated nyob rau hauv thawj thaiv, raws li nyob rau hauv lub xov tooj cua-zaus amplifier, thiab nyob rau hauv ib tug cascade tov. ntau zog tau kom tsis txhob muaj nrog receiver suab nrov mus rau ib tug tsawg kawg nkaus theem. Raws li ib tug tshwm sim, muaj tsis muaj suab nrov circuits thiab Cheebtsam.

Sab nraud cuam yuav ua rau muaj teeb meem nrog kev txais tos ntawm tsis muaj zog Pib ntsais koj teeb rau ob yog vim li cas. Ua ntej, lub suab nrov ntes tau los ntawm lub kav hlau txais xov, yuav npog lub tawm. Yog hais tias tus tom kawg yog nyob ze los yog hauv qab no rau theem ntawm kev tuaj nrov nrov, tus txais tos yog suab tsis yooj yim sua. Ib txhia tej tswv yuav tau txais tshaj tawm hauv xov nyob rau hauv lub Far East, txawm nyob rau hauv siab cuam tshuam, tab sis lub suab thiab lwm yam kev pib xyaum ua tseg nyob rau hauv cov tej yam kev mob yog tsis meej.