m., r». I 11I 411.1ME

Transcription

1 I I 4 'Á Í ( m, r» I I 4ME A PUBLICATION OF THE TUBE DEPARTMENT RCA HARRISON, N J Volum 3, No January Marh, 953 GEORGE M ROSE, K2AH, AND HIS HISTORY MAKING, 46 MC TRANSISTOR TRANSMITTER (S pag 3 or story)

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4 January Marh, 953 RCA HAM TIPS 4 th oil is 3/4 inh (masurd rom th ntr o th wir as shown in Fig 2), th oil will hav an indutan o approximatly 025 µh (inluding th indutan o th on inh lads) Coils wound in aordan with Figurs I and 2 ar suiintly aurat or most TVI appliations; thy may b soldrd into a lowpass iltr without urthr adjustmnt I dsird, th oil may b wound to othr dimnsions Th nomograph shown in Fig 4 ailitats th sltion o suitabl valus o indutan and apaitan or a iruit rsonant at a givn rquny For xampl, th indutan nssary or rsonan at 6725 M with a 20µµ apaitor an b dtrmind by plaing a straight dg on th nomograph so that it onnts th 6725 M point on th rquny sal and th 20µµ point on th apaitan sal Th intrstion o th straight dg with th indutan sal dtrmins th rquird indutan valu Th indutan, apaitan, and rquny rangs ovrd in this nomograph ar appliabl to most lowpass, TVI iltr dsigns Masurmnts Th indutan o th oil may b masurd with a Q mtr, or it may b hkd in a rsonant iruit with a grid dip mtr as shown in Fig 3 To ailitat masurmnt o indutan in a rsonant iruit with a grid dip mtr, a alibratd variabl apaitor should b inludd in th rsonant iruit Sin suh a apaitor annot b ound in th avrag ham shak, a rasonably aurat apaitan standard an b mad rom a st o six silvr mia apaitorson ah o 5, 0, 20, 40, 70, and 00 µµ (iv pr nt tolran) Combinations o ths six apaitors will provid a apaitan rang o 5 to 50 µµ in 5 µµ stps Errors an b kpt to a minimum by lipping th apaitor lads short and by soldring short onntions to th oil bing tstd Lumping o apaitan tolran rror an b minimizd by using a singl apaitor whnvr asibl rathr than a ombination o apaitors; th us o a singl apaitor is pratial whn th rquny o th signal sour an b varid Th XYL's TV rivr an b usd to alibrat th grid dip osillator On or two wid, blak, vrtial bars will b visibl on th kinsop whn th grid dip osillator rquny is approximatly th sam as th pitur arrir rquny Whn th osillator rquny approahs th sound arrir rquny, a T6 w signal will manat rom th spakr Th distan btwn th TV antnna transmission lin and th grid dip mtr may b iv t or mor during this alibration TV sound and pitur arrir rqunis or svral hannls ar indiatd on th nomograph, Fig 4, or onvnint rrn whn a TV rivr is usd or alibrating th grid dip osillator Th TV rivr an also b usd, alon, as a rsonan indiator whn a grid dip mtr is not availabl* Whn this mthod is mployd, th paralll rsonant iruit ontaining a known apaitan and an unknown indutan is onntd btwn on sid o th 300 ohm transmission lin and th TV rivr antnna trminal as shown in Fig 3b Whn th indutor and th apaitor ar rsonant at a pitur arrir rquny, th pitur brightnss is rdud Whn th indutor and apaitor ar rsonant at a sound arrir rquny, th volum is rdud Two xampls ar givn blow to illustrat this mthod o adjusting oils to spii in dutan valus In ah as, th oil is onntd in paralll with a apaitor (dtrmind rom th nomograph or a givn TV sound or pitur arrir rquny) and onntd in on sid o th transmission lin as dsribd abov Exampl Using Channl 2 arrir rqunis, adjust a TVI indutor or an indutan o 02 µh (a) From th nomograph, slt th valu o apaitan nssary or rson Th Pratial Sid o Building TVI Filtrs," by J H Owns, "Radio Eltronis," May, 952 Fig 3 Two mthods o hking indutan by th rsonant iruit mthod Capaitor C is a silvr mia typ o known apaitan, and L is th unknown indutan LO 00 IIIHIIII C SEE TEXT) (a) GRID DIP OSCILLATOR METHOD (b) TV RECEIVER METHOD

5 January Marh, 953 RCA HAM TIPS 5 an with a 02 ph oil at 5525 or 5975 mgayls: (C = 4 µµ or th pitur arrir rquny, and 36 o or th sound arrir rquny) (b) Compar ths valus o apaitan with standard valus o silvr mia apaitors and slt th losst availabl apaitor 40 µµ in this as Connt th oil aross th 40µµ apaitor and prun th oil and vary th spaing btwn th turns until th Channl 2 pitur brightnss drass to a minimum Th indutan o th oil will thn b los nough to 02 µh or TVI iltr appliations Exampl 2 Sam as Exampl I xpt Channl 3 arrir rquny is usd as th rsonant rquny (a) From th nomograph, slt th valu o apaitan nssary or rsonan with a 02 ph oil at 625 or 6575 mgayls: (C = 35 µµ at th pitur arrir rquny, and 30 µµ at th sound arrir rquny) (b) Us a apaitan o 30 µµ (20 and 0µµ apaitors in paralll) Prun th oil and vary th spaing btwn th turns until th Channl 3 sound drops to a minimum Fig 4 Nomograph or dtrmining any on o th thr paramtrs, indutan, apaitan, or rsonant rquny o a paralll rsonant iruit whn th othr two ar known For a givn rquny,, and th dsird indutan, L, th valu o apaitan or th paralll iruit shown in Fig 3 is dtrmind by th intrstion, C, o lin AB and th apaitan sal FREQUENCY (M) s LC INDUCTANCE (Chi CAPACITANCE (C ) II 005 = X30 0 C ' (SOUND} 02 CHANNEL 6 5 (PIX) 83 25, 6 75, (PIX) 7725, 05 (SOUND) 80 CHANNEL " (SOUND) TO CHANNEL 4 (FIX) 6725 A (5OUND) CHANNEL (P IX) ,5' 50 OUND) CHANNEL 2 (PIX) , 50 0 = 5 = 2 5 to I

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