I N STRUCTI ON M AN UAL 334B 2000 WATT VHF LOW BAND TRANSMI TTER AXCERA, LLC 103 FREEDOM DRI VE P.O. BOX 525 LAWRENCE, PA 15055- 0525 USA ( 724) 873- 8100 • FAX ( 724) 873- 8105 w w w . ax cera. com • info@axcera.
000- Wat t VHF Low Band Tr ansm it t er Table of Cont ent s TABLE OF CON TEN TS CHAPTER 1 I NTRODUCTI ON SECTI ON 1.1 1.2 1. 3 1.4 1.5 1.6 PAGE Manual Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Assem bly Designat ion Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Safet y. . . . . . . . . . . . . . . . . . . . . .
2000- Wat t VHF Low Band Tr ansm it t er Table of Cont ent s TABLE OF CON TEN TS ( cont inued) SECTI ON PAGE 4.4 Harm onic Filt er, Bandpass Filt er and Coupler Assem bly . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 31 CHAPTER 5 DETAI LED ALI GNMENT PROCEDURES 5.1 5.2 5.3 5.4 5.5 5.6 VHF Low- Band Excit er Tray wit h Baseband Video and Audio I nput s . . . . . . . . . . . 5- 1 VHF Excit er Tr ay w it h 4.5- MHz Com posit e I nput Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2000- Wat t VHF Low Band Tr ansm it t er Table of Cont ent s LI ST OF FI GURES FI GURE PAGE 3- 1 3- 2 1 kW Minim um Vent ilat ion Configurat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 4 Chassis Trak Cabinet Slides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 5 5- 1 Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2000- Wat t VHF Low Band Tr ansm it t er Table of Cont ent s LI ST OF TABLES TABLE PAGE 2- 1 2- 2 2- 3 2- 4 2- 5 2- 6 2- 7 2- 8 2- 9 2- 10 334B Trays and Assem blies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 1 VHF Excit er Tray Met ers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 5 VHF Excit er Tray Swit ches . . . . . . . . . . . . . . . . . . . . . .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 1, I nt r oduct ion Ch a pt e r 1 I ntroduction This m anual explains t he inst allat ion, set up, alignm ent , and m aint enance procedures for t he 334B 2000- w at t solid st at e VHF Low Band t ransm it t er. I t is im port ant t hat you read all of t he inst r uct ions, especially t he safet y inform at ion in t his chapt er, before you begin t o inst all or operat e t he unit . provided in t he appendices.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 1, I nt r oduct ion Follow I nst ruct ions – All of t he operat ing and use inst ruct ions for t he t ransm it t er should be followed. 2. 3. 4. Cle a ning – Unplug or ot herwise disconnect all pow er fr om t he equipm ent before cleaning. Do not use liquid or aerosol cleaners as dam age t o silk screens m ay occur. Use a dam p clot h for cleaning. 5. Ve nt ila t ion – Openings in t he cabinet s and t ray front panels are provided for vent ilat ion.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 1, I nt r oduct ion When shipping an it em t o Axcera, please include t he MRA# on t he packing list and on t he shipping cont ainer. The packing list should also include cont act inform at ion and a brief descript ion of why t he unit is being ret urned.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions Ch a pt e r 2 Syst em Descript ion, Maint enance & Rem ot e Cont rol Connect ions The 334B is a com plet e 2000- w at t VHF Low Band solid st at e int ernally diplexed t elev ision t r ansm it t er t hat oper at es at a nom inal visual out put power of 2000 w at t s peak sy nc and an av erage aural out put pow er of 200 w at t s, at an A/ V rat io of 10 dB, 10% sound, or 100 wat t s
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions m odulat ed 4.5 MHz I F, from t he aural I F synt hesizer board, is m ixed wit h t he 45.75 MHz CW t o produce a m odulat ed 41.25 MHz aural I F out put . The video m odulat ed 45.75 MHz is t hen diplexed w it h t he audio m odulat ed 41.25 MHz t o produce t he com bined Visual I F + Aural I F out put of t he boar d t hat connect s t o t he ALC board.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions Channel Oscillat or Board VHF Low Band Am plifier Tray NOTE: I f t he pr ecise fr equency kit is present in your t ransm it t er, t he VCXO Channel Oscillat or Board ( 1145- 1204) will be used. Th e out put s of t he split t er feed t he t hr ee ( A6, A7 and A11) VHF am plifier t rays ( 1304363) .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions NOTE: I f t he rem ot e int erface panel is not present in your t ransm it t er t he dum m y j um per plug m ust be present on J11, wit h a j um per bet ween pins 23 and 24, locat ed on t he back of t he VHF excit er t ray. The j um per provides t he int erlock needed for t he t ransmit t er t o oper at e.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions 2 .2 .1 VHF Excit er Tray ( A4 ) Table 2- 2. VHF Ex cit er Tr ay Met er s METER M e t e r ( A4 - A1 8 ) 334B, Rev. 0 FUN CTI ON This m et er reads pow er in t erm s of a percent age of t he calibrat ed out put pow er level on t he upper scale. The volt age level or fr equency level is r ead on one of t he bot t om t w o scales. A fullscale reading on t he t op scale is 120% .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions Table 2- 3. VHF Ex cit er Tr ay Sw it ches SW I TCH S1 Tr ansm it t er Oper at e/ St andby S2 Mode Select Aut o/ Manual R1 Power Adj ust FUN CTI ON The m om ent ary swit ch S1 applies a ground t o K1, a lat ching relay on t he t ransm it t er cont rol board. K1 will swit ch eit her t o Operat e or t o St andby depending on w hich direct ion S1 is pushed.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions 2 .2 .2 VHF Am plifier Tray ( A6 , A7 & A1 1 ) Table 2- 6. VHF Am plifier Tr ay Sw it ches SW I TCH CB1 On/ Off Circuit Breaker S1 Sw it ch , M e t e r S2 Sw it ch , M e t e r 334B, Rev. 0 FUN CTI ON Swit ches 220 VAC t hrough a 15- am p circuit breaker- t y pe pr ot ect ion dev ice. The sw it ch light s if AC is pr esent .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions Table 2- 7. VHF Am plifier Tray Fault I ndicat or s I NDI CATOR DS1 Overdrive DS2 Enable DS3 Module St at us DS4 VSWR Cut back DS5 Overt em perat ure DESCRI PTI ON I ndicat es t hat t he lev el of dr iv e is t oo high. The pr ot ect ion circuit will lim it t he drive level t o t he set t hreshold. The fault is generat ed on t he overdrive prot ect ion board.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions t his dat a be ret ained in a rugged folder or envelope. A sam ple form at for a log sheet is provided in Appendix B. Phot ocopies of t he log sheet should be m ade t o allow you t o m ake cont inued dat a ent r ies. syst em , t he baseband video and audio input s connect dir ect ly t o t he r ear of t he VHF excit er. NOTE: I f your t ransm it t er does not cont ain t he 4.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions Table 2- 10. 334B Rem ot e I nt erface Connect ions t o ( A12) t he A/ V I nput and Rem ot e I nt er face Assem bly REMOTE JACK/ PI N N UMBER FUN CTI ON Transm it t er Enable I nt erlock J9- 21 Transm it t er Enable I nt erlock Rt n. J9- 22 I NTERFACE TYPE J9- 21 and J9- 22 m ust be connect ed t oget her for norm al operat ion.
2000- Wat t VHF Low Band Tr ansm it t er FUN CTI ON Chapt er 2, Sy st em Descr ipt ion, Maint enance & Rem ot e Cont r ol Connect ions REMOTE JACK/ PI N N UMBER Re m ot e M e t e r ing I NTERFACE TYPE Visual Out put Pow er Visual Out put Pow er Rt n J9- 1 J9- 2 1V full scale at 1kΩ sour ce r esist ance Aural Out put Power Aural Out put Power Rt n J9- 3 J9- 4 1V full scale at 1kΩ sour ce r esist ance Reflect ed Pow er Reflect ed Pow er Rt n J9- 5 J9- 6 1V full scale at 1kΩ sour ce r esist ance
00- Wat t VHF Low Band Tr ansm it t er Chapt er 3, I nst allat ion and Set up Procedures Ch a pt e r 3 I nst allat ion and Set up Procedures Ther e ar e special consider at ions t hat need t o be t ak en int o account befor e t he 334B can be inst alled. For exam ple, if t he inst allat ion is com plet ed during cool w eat her , a heat - relat ed problem m ay not sur face for m any m ont hs, suddenly appearing during t he heat of sum m er.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 3, I nst allat ion and Set up Procedures Now t hat t he am ount of heat t hat m ust be rem oved is known, t he next st ep is t o det erm ine how t o accom plish t his. The opt ions are air condit ioning, vent ilat ion, or a com binat ion of t he t wo. Air condit ioning is always t he preferred m et hod and is t he only w ay t o cr eat e anyt hing close t o an ideal environm ent . t ransm it t er under cert ain condit ions.
2000- Wat t VHF Low Band Tr ansm it t er 5. 6. 7. 8. 9. 10. Chapt er 3, I nst allat ion and Set up Procedures The ex haust should be locat ed as high as possible. Som e duct ing is usually required t o insure t he com plet e flushing of heat ed air w it h no st agnant ar eas. The ar ea of t he filt er , locat ed in t he duct ing, m ust be large enough t o insure a maxim um air velocity of 300 feet per m inut e t hrough t he filt er .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 3, I nst allat ion and Set up Procedures Figur e 3- 1. 1 kW Minim um Vent ilat ion Configurat ion Rem ove t he cabinet and t he t rays from t he cr at es and boxes. Rem ove t he st r aps t hat hold t he cabinet t o t he shipping skid and slide t he cabinet from t he skid. Rem ove t he plast ic wrap and foam prot ect ion from around t he cabinet .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 3, I nst allat ion and Set up Procedures Figur e 3- 2. Chassis Trak Cabinet Slides Open t he rear door and inspect t he int erior of t he cabinet for packing m at erials and carefully rem ove any t hat are found. Slowly slide each t ray in and out t o v er ify t hat t hey do not r ub against each ot her and hav e no r est r ict ions t o free m ovem ent . I t m ay be necessary t o adj ust t he posit ion of t he t r ay s t o k eep t hem from rubbing.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 3, I nst allat ion and Set up Procedures This com plet es t he unpacking and inst allat ion of t he 334B 2000- w at t VHF t elevision t ransm it t er . Refer t o t he set up and operat ion procedures t hat follow before applying power t o t he t ransm it t er. I f t he ( A12) A/ V input and rem ot e int erface assem bly is not present in t he sy st em , connect ions ar e m ade dir ect ly t o t he r ear of t he VHF ex cit er t r ay.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 3, I nst allat ion and Set up Procedures panels of t he VHF am plifier t rays, in t he power supply posit ion. not be t he sam e. Refer t o t he Test Dat a Sheet for t he t r ansm it t er t o com par e t he final readings from t he fact ory wit h t he r eadings on each of t he t r ay s aft er t he set up.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions Ch a pt e r 4 Circuit Descriptions is applied t o t he boar d. The out put s of U1B and U1C are applied t o t he different ial am plifier U1A t hat elim inat es any com m on m ode signals ( hum ) on it s input leads. A pre - em phasis of 75 µs is provided by R11, C11, and R10 and can be elim inat ed, if not needed, by rem oving t he j um per W5 on J5.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions m ode signals ( hum ) t hat m ay occur on it s input leads. The com posit e audio input signal is applied t o t he am plifier U2B whose gain is cont rolled by t he com posit e audio gain pot R17. The com posit e audio signal is t hen connect ed t o t he sum m ing point at U2D pin 13. U11B. The out put of U11B is connect ed t o t h e 4 . 5- MHz out put j acks at J7 and J8. 4.1.1.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions - 12 VDC is connect ed t o J1- 5 and filt ered by L1, C1, and C2 befor e it is connect ed t o t he r est of t he boar d. Tw o connect ions of t he + 12 VDC are t o U8 and U9, which are 5- volt regulat or I Cs t hat pr ov ide t he v olt age t o t he U10 and U5 I Cs. Test point TP1 is provided t o m onit or t he lev el of t he input .
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions video t hat is split off from t he m ain video pat h at t he em it t er of Q3. The v ideo sam ple is buffered by U3A and connect ed t o U4A. The lev el at w hich t he t ip of sy nc is clam ped, approxim at ely - 1.04 VDC, as m easur ed at TP2, is set by t he v olt agediv ider net w or k connect ed t o U4A. I f t he video level changes, t he sam ple applied t o U4A changes.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions 1, t he L input of m ixer Z1. The adj ust able capacit or C78 and resist or R53 are set up t o add a sm all am ount of incident al carrier phase m odulat ion ( I CPM) cor r ect ion t o t he out put of t he m ixer st age t o com pensat e for any nonlinearit ies generat ed by t he m ixer. 45.75- MHz I F carrier oven oscillat or board or t he I F VCXO board, in a precise frequency syst em . The m odulat ed baseband 4.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions The Mixer Z2 het erodynes t he auralm odulat ed, 4.5- MHz signal wit h t he 45.75- MHz CW signal t o produce t he m odulat ed 41.25- MHz aural I F signal ou t pu t . com bines t he NI CAM signal wit h t he 45.75- MHz visual I F + 41.25- MHz aural I F signal. The out put of t he m ixer at pin 4, t he R out put , is fed t o a bandpass filt er t hat is t uned t o pass only t he m odulat ed 41.25MHz aural I F signal.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions is at t ained. The delay - equalized video signal out put of t he board is at J1- 4. A sam ple of t he delayed video signal is provided at J2 on t he board and can be used for t est ing purposes. pF, prevent s t he oscillat or from being loaded down by Q2. Q2 is operat ed as a com m on- em it t er am plifier st age whose bias is provided t hrough R8 from t he + 12 VDC line.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions The st ages U1, U2, U3, Q5, and Q6 are powered by + 5.1 VDC, which is obt ained from t he + 12 VDC line volt age using t he v olt age- dropping resist or R16 and t he zener diode VR2. 10 pF, prevent s t he oscillat or from being loaded down by Q2. Q2 is operat ed as a Com m on Em it t er Am plifier st age whose bias is provided t hrough R8 from t he + 12 VDC line.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions volt age dropping resist or R16 and Zener Diode VR2. I f a receiver t ray is part of your syst em , t hen t he r elays need t o be cont r olled by t he Modulat or Select com m and t hat is connect ed t o J30 on t he boar d, so t hat eit her t he receiver I F or t he m odulat or I F can be used by t he boar d.
2000- Wat t VHF Low Band Transm it t er 4.1.5.5 Main I F Signal Pat h ( Part 1 of 3) The select ed visual + aural I F input ( 0 dBm ) signal is split at L1 and L2, wit h one half of t he signal flowing t hrough L1 and ent ering a bandpass filt er t hat consist s of L3, L4, C4, L5, and L6. This bandpass filt er can be t uned w it h C4 and is subst ant ially broader t han t he I F signal bandw idt h.
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions com parat or circuit m ade up of U9C and U9D. The r efer ence volt age for t he com parat ors is det erm ined by a volt age divider net work consist ing of R129, R64, R65, R66, and R130, off t he - 12 VDC line. When t he input signal level falls below t his reference t hreshold, w hich act s as a loss of sy nc det ect or cir cuit , t he out put s of U9C and U9D m ove t owards t h e - 12 VDC rail.
2000- Wat t VHF Low Band Transm it t er at t enuat or ( m inim um signal out put ) . By cont r olling t he value of t he volt age applied t o t he pin diodes, t he I F signal level is m aint ained at t he set level. 4.1.5.8 Main I F Signal Pat h ( Part 2 of 3) When t he I F signal passes out of t he pindiode at t enuat or t hrough C11, it is applied t o t he m odular am plifier U1.
2000- Wat t VHF Low Band Transm it t er sam ple of t he correct ed I F is provided at TP2. The I F out put is nor m ally connect ed t o an ext er nal I F phase cor r ect or boar d. Chapt er 4, Cir cuit Descr ipt ions fr equency- r esponse cor r ect ion t ak es place. 4.1.5.11 ALC Circuit 4.1.5.10 Main I F Signal Pat h ( Part 3 of 3) Aft er t he I F signal passes t hr ough t he ext ernal I F phase correct or board, it ret urns t o t he ALC board at I F input j ack J7 (0 dBm ).
2000- Wat t VHF Low Band Transm it t er This ALC volt age, and t he DC level corresponding t o t he I F level aft er signal correct ion, are fed t o U10A pin 2, w hose out put at pin 1 connect s t o t he ALC pindiode at t enuat or circuit , CR1 - CR3.
2000- Wat t VHF Low Band Transm it t er t han j ust pulling t he ALC reference down. Two different m echanism s are em ployed. One is a very fast - act ing cir cuit t o incr ease t he at t enuat ion of t he pin- diode at t enuat or, CR3, CR1, and CR2, and t he second is t he r efer ence v olt age being pulled away from t he ALC am plifier device.
2000- Wat t VHF Low Band Transm it t er t he signal. This at t enuat ion is adj ust ed by adding R7, a variable resist or, in parallel wit h t he L- pad. R7 is only in parallel when t he signal reaches a level large enough t o bias on CR1 and CR2 t hat allow s current t o flow t hrough R7. When R7 is put in parallel wit h t he L- pad, t he at t enuat ion t hr ough t he L- pad is low er ed, causing black st r et ch.
2000- Wat t VHF Low Band Transm it t er The am ount of st ret ch is det erm ined by t he adj ust m ent of R35. The signal is next applied t o t he am plifier U5 t o com pensat e for t he loss in level t hr ough t he L- pad. The breakpoint , or cut - in point , for t he cor r ect or st age is set by cont rolling where CR8 and CR9 t urn on. This is achieved by adj ust ing t he cut - in resist or R31 t o form a volt age divider from + 6.8 VDC t o ground.
2000- Wat t VHF Low Band Transm it t er at J2. The t ypical LO signal out put level is + 5 dBm . The volt age m easured at TP2 is t ypically + 0.6 VDC. The + 12 VDC for t he board ent ers t hrough j ack J3- 3 and is filt ered by L3, C2 and C7 before being dist ribut ed t o t he r est of t he boar d. 4 .1 .7 .
2000- Wat t VHF Low Band Transm it t er or aut o gain by it s posit ion on t he j ack. Bet ween 1 and 2 is m anual gain, which uses pot R9 t o set t he out put lev el. Bet ween pins 2 and 3 is aut o gain, which uses an ext er nal cont r ol volt age input at j ack J4 as t he level cont r ol. NOTE: Th e 334B t ransm it t er operat es in Manual only. The level set RF is pre - am plified by U1 and connect ed t o Q1, t he out put am plifier for t he board.
2000- Wat t VHF Low Band Transm it t er st andby indicat or, if present , and J18- 1. The low from U4B- 13 also connect s t o Q10, w hich is biased on, and connect s a high t o Q6, Q7, Q8, and Q9, which are biased on and apply - 12 VDC enables t o J8- 2, J8- 3, J8- 4, and J8- 5 t hat connect t o t he VHF am plifier t rays.
2000- Wat t VHF Low Band Transm it t er 4.1.8.3 The Aut om at ic Turning On and Off of t he Tr ansm it t er Using t he Pr esence of Video. The t ransm it t er cont rol board also allows t he t r ansm it t er t o be t ur ned on and off by t he pr esence of v ideo at t he t ransm it t er when t he t ransm it t er is in Aut o. When a v ideo fault occur s due t o t he loss of video, J7- 5 goes low .
2000- Wat t VHF Low Band Transm it t er high at U5C pins 8 and 9, causes it s out put at pin 10 t o go low . This low is connect ed t o U5D pin 12. I f t he t ransm it t er is in Aut o, pin 13 of U5D is also low. The lows on pins 12 and 13 cause t he out put of U5D t o go high and forward bias Q19. The drain of Q19 goes low and energizes t he coil con n ect ed t o pins 1 and 6 in relay K1, causing it t o sw it ch t o St andby .
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions J8- 37 for t he connect ion t o a r em ot e VSWR cut back indicat or. Q25, w hich is biased on and causes t he drain t o go low . The low is connec t ed t o J8- 12, which can light any rem ot e r eceiv er fault indicat or t hat is connect ed t o it . 4.1.8.
2000- Wat t VHF Low Band Transm it t er • • • • % Aural power = 100% % Excit er = The level on t he m et er needed t o at t ain 100% out put power from t he t ransm it t er ALC = .8 VDC Audio = ± 25 kHz wit h a balanced audio input or ± 75 kHz wit h a com posit e audio input Refer t o t he t est dat a sheet for t he t ransm it t er for t he act ual reading: Chapt er 4, Cir cuit Descr ipt ions for m onit oring on t he front panel m et er.
2000- Wat t VHF Low Band Transm it t er 4.1.9.2 Visual Level Circuit The ot her det ect ed visual + aural level out put from U6B is connect ed t o U1C and, if t here is no scram bling, connect s direct ly t o int ercarrier not ch L3, w hich is adj ust ed t o filt er out t he aur al and t he 4. 5- MHz int ercarrier frequencie s, leaving only a visual + sync out put . The visual + sy nc out put is fed t o a peak det ect or circuit consist ing of CR5 and U2A.
2000- Wat t VHF Low Band Transm it t er ( 1145- 1201) t hat gener at es a st able fr equency r efer ence signal of approxim at ely 100 MHz. The channel oscillat or assem bly is an enclosure t hat provides t em perat ure st abilit y for t h e cr y st al oscillat or . An SMA out put at j ack J1 and an RF sam ple at BNC connect or j ack J2 are also part of t he assem bly. Adj ust m ent s can be m ade t hr ough access holes in t he t op cover of t he assem bly.
2000- Wat t VHF Low Band Transm it t er det erm ines t he lengt h of t im e bet ween t he sending of t he ident ificat ion code. R14 is adj ust ed t o set t his t im e int erval. R14, fully CW, is t he longest int erval bet w een ident ificat ion calls, approxim at ely eight m inut es. R14, fully CCW, is t he shor t est int er v al bet w een t he sending of t he code ( approxim at ely 10 seconds) .
2000- Wat t VHF Low Band Transm it t er Chapt er 4, Cir cuit Descr ipt ions assem bly) M AJOR ASSEM BLY DESI GNATOR A3- A2 A3- A3 A4- A1, A4- A2 and A4- A3 A5- A1 A13 A8 A10 BOARD/ ASSEMBLY N AME Overdrive prot ect ion board ( m ount ed in [ A3] an RF enclosure assem bly) 3- way split t er board ( m ount ed in [ A3] an RF enclosure assem bly) Three low band VHF am plifier pallet s ( m ount ed in [ A4] an RF enclosure assem bly) 3- way com biner board ( m ount ed on [ A5] t he com biner heat sink assem b
2000- Wat t VHF Low Band Transm it t er J1 on t he low band VHF am plifier board ( 1198- 1605) t hat am plifies t he signal approxim ately 22 dB. The RF out put of t he low band VHF am plifier board at J2 ( + 41.5 dBm ) connect s t o J4 of ( A3 - A2) t he overdrive prot ect ion board ( 1198- 1601) . The RF signal is t hr ough connect ed dir ect ly t o J5, t he RF out put j ack of t he boar d. A sam ple of t he RF on t he board is applied t o a diode- det ect or cir cuit t hat consist s of CR1 and U1A.
2000- Wat t VHF Low Band Transm it t er shift er board, t he ( A2- A2) filt er/ am plifier board and t he ( A3- A2) overdrive pr ot ect ion boar d. The fuses F1, F2 and F3 ar e 20- amp fu ses. F4 is a 5- am p fuse, F6 is a 2- amp fuse, and F7 is a 1- am p fuse. F5 is not used in t his configurat ion.
2000- Wat t VHF Low Band Transm it t er Fr ont Panel Met er ing The front panel m et er ( A9) uses t he front panel Select or swit ch S1 t o m o nit or t he AGC Volt age, % Forward Power, % Reflect ed Pow er , t he pow er supply volt age, and t he cur r ent . The m et er in t he AGC posit ion will read bet ween 1 and 2 volt s. The pow er supply volt age reading is calibrat ed using R86 on t he AGC cont rol board.
2000- Wat t VHF Low Band Transm it t er connect or J2 is t hen fed t o t he ant enna for your syst em . 334B, Rev. 0 Chapt er 4, Cir cuit Descr ipt ions This com plet es t he descr ipt ion of t h e 334B VHF Low Band Transm it t er.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures Ch a pt e r 5 Det ailed Alignm ent Procedures The 334B t ransm it t er was aligned at t he fact ory and should not require addit ional alignm ent s t o achieve norm al operat ion. int er face panel.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures 5 .2 ( A4 ) VH F low - Ba n d Ex cit e r Tr a y w it h t he 4 . 5 - M H z Com posit e I nput Kit ( NOTE: I f your t ransm it t er does not cont ain t he 4.5MHz com posit e input kit , skip t his sect ion.) changed w it h t he adj ust m ent of t he envelope delay. 5 .3 ( A4 ) VH F Ex cit e r Tr a y w it h eit her Ba se b a n d or t h e 4 .5- M H z Com posit e I nput Wit h t he 4.
2000- Wat t VHF Low Band Tr ansm it t er • DS4 ( Mut e) – I ndicat es t hat a v isual Mut e com m and is present . ( NOTE: not used in t his configurat ion) • DS5 ( Modulat or Enable) – I ndicat es t hat t he m odulat or I F out put has been select ed ( NOTE: t his is only used if a receiver t ray is present in t he syst em . DS5 is always on wit h no receiver pr esent .) Chapt er 5, Det ailed Alignm ent Procedures clockw ise ( CCW) .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures t hreshold point . Refer t o t he assem bly drawing for t he ALC board ( 1265- 5305) , t o find t he adj ust m ent s for t he fir st t hrough t hird linearit y correct or st ages. Because t he st ages ar e cascaded, t he order of correct ion is im port ant .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures ( 1142- 1601) in Manual. The idling current s for t he am plifier boards are adj ust ed wit h no RF drive applied. Remember t o put S1 back t o t he Aut o AGC posit ion aft er any adj ust m ent s. Aut o AGC is t he norm al posit ion during operat ion of t he t ransm it t er.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures t o 110% , sync only, and adj ust R12 unt il t he out put pow er begins t o dr op off. Ret ur n t he out put pow er level of t he t ransm it t er t o 100% . in t he VHF L.B. am plifier t ray, t o t h e Manual posit ion. Turn t he t ransm it t er t o t he Oper at e posit ion. 2. Connect a sy nc and black t est signal t o t he video input j ack of t he r em ot e int erface panel. 5 .6 .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures panel light s. This set s up t he VSWR cut back cir cuit r y . Readj ust R5 for 100% on t he m et er t o achiev e a 750 w at t s peak of sy nc out put + 75 wat t s aural power. However, if t he syst em requires less out put power per am plifier t ray, adj ust each t ray by t he sam e am ount t o give t he desired t ot al out put pow er .
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures Reflect ed Pow er . Be car eful not t o incr ease Reflect ed Pow er on t he ot her Am plifier Trays. The Am plifier Trays should int er act in such a w ay t hat t he phasing of any one am plifier t ray will affect t h e Reflect ed on t h e ot her am plifier t r ay s. Wit h t he spect r um analy zer set t o t he zero span m ode, obt ain a peak reference on t he scr een.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures 5 .1 0 ( A8 ) 3 - W a y Com bin e r Asse m bly ( 1 0 6 5 2 4 1 ; Appe ndix C) The t r ay has been fact or y t uned and should not need any alignm ent s t o achieve norm al operat ion. To align t he t r ay for t he 4. 5- MHz com p osit e input , apply t he 4.
2000- Wat t VHF Low Band Tr ansm it t er and pot ent iom et ers ( R7, R12, R17, and R22) unt il t he signal at t ains t he FCC gr oup delay cur v e. The st ages are arranged in order of increasing frequency. Adj ust R29, as needed, t o at t ain t he sam e lev el out of t he board as int o t he board. 5 .1 2 .3 ( Opt iona l) ( A2 4 ) Com posit e 4 . 5- M H z Filt er Boa rd ( 1 2 2 7 - 1 2 4 4 ; Appendix D) This boar d is par t of t he 4.5- MHz input kit and will only funct ion properly wit h a 4.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures j um per W7 on j ack J4 t o t he Clamp - Off, Disable, posit ion. 3. Connect a 5- st ep st air case v ideo t est signal t o t he input of t he t ransm it t er. 4. Monit or TP2 w it h an oscilloscope. Adj ust R12, t he video gain pot , for 1 Vpk- pk. 5. Change t he video input t est signal t o a m ult iburst t est pat t ern. While m onit oring TP2, adj ust C8 and R32 for a flat - fr equency r esponse.
2000- Wat t VHF Low Band Tr ansm it t er 10. Move j um per W7 on J4 t o t he Clam p Enable posit ion. Readj ust pot R152, dept h of m odulat ion, for t he cor r ect dept h of m odulat ion. 11. Set t he waveform m onit or t o display I CPM. Preset R53 fully CCW, adj ust C78 for t he gr eat est effect at whit e on t he I CPM display, and t hen adjust R53 for m inim um I CPM. 12. Recheck t he dept h of m odulat ion and, if necessary, adj ust R152, dept h of m odulat ion. 13.
2000- Wat t VHF Low Band Tr ansm it t er D. 2. 3. Connect a cable from t he 600Ω audio out put j ack of t he dem odulat or t o t he input of an audio dist ort ion analyzer. Set t he out put fr equency of t he audio oscillat or t o 400 Hz and t he output level to + 10 dBm . Chapt er 5, Det ailed Alignm ent Procedures 4. Adj ust R13, balanced audio gain, on t he aural I F synt hesizer board for ± 25- kHz deviat ion. 5. Check t he dist ort ion on t he aural dist ort ion analyzer ( THD= < 0.5% ) . 6.
2000- Wat t VHF Low Band Tr ansm it t er Chapt er 5, Det ailed Alignm ent Procedures 2. 3. Place j um per W3 on j ack J6 in t he Manual m ode and adj ust R87 for 0.5 v olt s at TP4. 4. Place j um per W3 on J6 in t he Aut o m ode and adj ust t he front panel pow er adj ust c ont rol A20 fully CW. I f t he ( opt ional) rem ot e power raise/ lower kit is present , t hen adj ust sw it ch S1 on t he boar d t o m axim um volt age at TP4. Adj ust R74, t he range adj ust , for 1 volt at TP4. 5.
2000- Wat t VHF Low Band Tr ansm it t er 9. of t he t ransm it t er. R103 and R106 ar e used t o adj ust t he dept h and w idt h of t he cor r ect ion not ch. 3. The linear it y cor r ect or s ar e set up during t he syst em alignm ent procedure. Cont rols R13, R18, and R23, t he m agnit ude cont r ols, should be set fully CW. Cont rols R34, R37, and R40 are t he linearit y cut - in adj ust m ent s. NOTE: Do not repeak C6, C18, L2, or L4. This m ay change t he out put level. 5 .1 2 .
2000- Wat t VHF Low Band Tr ansm it t er 5 .1 2 .1 3 ( A1 1 - A2 ) VHF Filter/ Mixer Boa rd ( 1 1 5 3 - 1 1 0 1 ; Appendix D) Typically a + 15dBm RF input at J3, a 0dBm com bined I F input at J7, and a RF out put of 0dBm at J2. To align t he board: 1. 2. Monit or J4, t he LO out put of t he board, wit h a spect rum analyzer and adj ust C12 and C18 for m axim um output (+ 14 dBm ) at t he LO frequency and m inim um out - of- band product s.
APPENDI X A SYSTEM SPECI FI CATI ONS
VHFSolidStateTransmitter/Translator 334B/336B434B/436B TheselowpowerVHFtransmittersandtranslatorsdeliverhighqualityandperformance inacompactandeconomicalpackage.Thetime-provenAxceraexciterprovidesa pre-correctedoutputdirectlytothehigh-gainfinalpoweramplifiermodules.The entirepackageishousedinasingle19inchrack-mountcabinet.
VHFSolidStateTransmitter/Translator 300/400Series 334B/336B434B/436B VisualPerformance AuralPerformance General PowerOutput 2000W PowerOutput(Average) 200W OutputImpedance 50Ω Distortion 0.5% FMNoise -60dB AMNoise -55dB AuraltoVisualSeparation 4.
APPENDI X B SAMPLE LOG REPORT SHEET AND TYPI CAL READI NGS
2000- Wat t VHF Low Band Tr ansm it t er Appendix B, Sam ple Log Report Sheet V H F Ex cit e r ( A4 ) ALC ( 0 t o 1 V) = ____________V % Aural Power ( 0 t o 120) = __________% % Excit er ( 0 t o 120) = ______________% Video ( 0 to 1 V) = ________________I RE % Reflect ed ( 0 t o 120) = ____________% Audio (0 to 100 kHz) = ____________kHz % Visual Power ( 0 t o 120) = _________% VH F Am plifie r Tr a ys # 1 ( A6 ) # 2 ( A7 ) AGC Volt age ( 0 t o 10 V) = ___________V AGC Volt age ( 0 t o 10 V) = _
2000- Wat t VHF Low Band Tr ansm it t er Appendix B, Typical Readings VH F Low Ba nd Ex cit e r Tr a y ( A4 ) ALC = .8V % Excit er = The level needed t o at t ain 100% out put power from t he t ransm it t er ( Typically bet ween 80 & 100% ) . % Reflected = < 10% % Visual Power = 100 % ( 2000 Wat t s Peak of Sync) % Aural Power = 100 % ( 200 Wat t s @ 10 dB A/ V Rat io) Video = 1 V at Whit e w/ .
2000- Wat t VHF Low Band Tr ansm it t er Appendix B, Sam ple Log Report Sheet VH F Am plifie r Tr a ys # 3 ( A1 1 ) AGC Volt age ( 0 t o 10 V) = ___________V % Reflect ed Power ( 0 t o 120) = _______% % Out put Power ( 0 t o 120) = ________% Power Supply Volt age ( 0 t o 100 V) = ___V Current ( 0 t o 10A scale, readings are t hen mult iplied by 2) Current I 1 = ___________A Current I 2 = ___________A Current I 3 = ___________A Current I D = ___________A Dat e __________________ Custom er Nam e __________
APPENDI X C ASSEMBLY DRAWI NGS AND PARTS LI STS
2000- Wat t VHF Low Band Tr ansm it t er 3 3 4 B Syst e m : 334B VHF Low 334B VHF Low 334B VHF Low 334B VHF Low Appendix C, Assem bly Drawings Band Transm it t er Typical Racking Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304405 Band Transm it t er Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304535 Band Transm it t er I nt erconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPENDI X D SUBASSEMBLY DRAWI NGS AND PARTS LI STS
2000- Wat t VHF Low Band Tr ansm it t er Appendix D, Subassem bly Drawings Different ial Gain Correct or Board Schem at ic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1138- 3107 AGC Cont rol Board Schem at ic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2000- Wat t VHF Low Band Tr ansm it t er Appendix D, Subassem bly Drawings ALC Board Schem at ic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1265- 3305 ( Opt ional) EEPROM FSK I dent ifier Board ( Used wit h AM I dent ifier Kit ) Schem at ic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .