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Ehrhorn Technological Operations
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PA-76
Operation Manual
20 pgs690.46 Kb0

Ehrhorn Technological Operations PA-76P, PA-76C, PA-76 Operation Manual

Ehrhorn Technotogical Operations, Inc.
Colorado Springs, C O 80919
OPERATING AND TECHNICAL MANUAL
HIGH FREQUENCY LINEAR POWER AMPLIFIERS
MODELS PA-76, PA-76P, and PA-76C
EHRHORN TECHNOLOGICAL OPERATIONS, INC.
Revised May 1, 1977
4975 North 30th Street
-1-
SECTION 1
GENERAL DESCRIPTION
T h e ALPHA 7 6 ( m od e l P A- 7 6 ) is a self-contained high frequency lin
e a r po wer amplifier ca pa bl e o f co ntinuous operation a t d - c p la te
po we r inp uts o f 2 . 5 ki lo wat ts PEP for S SB voice a nd o n e kilowatt av er age o r con tinuous ca rrier with no t im e limi t (NTL). T h e AL PH A
76 is tun abl e ov er t he ra ng e 1.8- 2.0 MH z plu s 3_3° M H z , opti mi zed
f o r conve nience i n t he six amat eur band s o f 1 0 through 1 60 m et e r s .
SPECIFICATION S (M od e l PA-76)
Fre quency Coverage: 1.8 -2.0 and 3- 30 M Hz (i ncl udin g 1 0- 16 0 me t er s ).
P la t e Power Input; 2 . 5 KW PE P /S S B, 1 KW average o r key d o w n , CC S.
R F Powe r Output: Typically 1. 5 KW PE P/SSB , 650 wa tts ca r rie r, CC S.
Driv e Powers Nominal 10 0 watt s P EP , 6 0 wa t ts c ar r ie r.
I np ut & Output Impedances; Nominal 5 0 o h m s re sis tiv e, unba lan ce d;
V SW R 2 : 1 o r l e s s .
Distortion: Third or de r I M more th an 30 3 b below 1 KW PE P o u t p u t .
Harmo nics : More tha n 5 0 d b below mean fundament al frequency o u t p u t .
T ub e Complement; Two Eim ac 88? ^ ceramic-metal grounded-grid triodes.
Cooling: Ful l-c abi net , du cte d fo rced a i r; centrifugal b lo w er. ALC: Adjustable thres hold , negative-going stan dard a s s hi p pe d. Protection: Primary fu s e s, plat e overcur rent r el a y, AC and HV
interlocks.
Primary Power: 24QV /10 A o r 12 0V /2 0A, no mi na l, 50 -60 Hz. S iz e and Weight: 7 . 5 " h . x 1 7 " w . x l4. 75 " d. Shipping w t . , 75 lb.
Op tio nal Modificat ions Available:
Op tio n "L" --
Ligh tweigh t Hipersir^ power transformer r ed uc es
Optio n "R " --
Model 76 ? --
Model 76C --
ne t an d shipping wei ght s by approximately 2 0 lb. HI/LO ( or "SSB/CW-TUNE”) tap ch an ge rela y , f ro n t
pa ne l con tr ol le d.
Id ent ica l with PA- 7 6 ab ove ex ce pt tu be co mplem ent
is th re e 8874's, increasing pl ate power in pu t rat
in g to 3 + KW PEP and typical rf ou tp ut t o 2 KW P EP . D oe s not affect long te rm average o r con ti nuo us power ratings.
"Co mm er ci al " model ide ntic al with PA-76 ex c ep t
tub e compl ement is th re e 8 8 7 4 ' power transfor
mer is spe cial 2. 4 KVA Hi per sir^ , an d option "R"
is st andar d. PEP ra ting s, d - c in pu t 3 K W , typi
c a l r f outp ut 2 K W ; co ntinuous carrier o r long
te rm av erage ra ti ng s, d - c in put 1. 6 K W, rf o ut p u t
1 KW C CS ( R AT T , A0, e t c . )
INS TALLATION
Unpacking: Carefully r em ov e amplifier and transfo rmer from car
t o n s ; SAVE ALL PACKING MATERIAL FO R RE-USE - SHI PMEN T OF TH E ALPH A
76 IN OTHER THAN FA CTORY PA CKING MAY RESULT IN DAM AGE NO T CO VER ED
2-
SE CTION 2
UNDER WA RR ANTY.
In sp ect cl osely fo r ev idence of shipping da ma ge ; i f any is f o u n d,
notify delivering car r ie r and se lle r a t o n c e . Com ple te warranty
registration fo rm an d mail t o ET O .
2. Transformer Installation; T h e t o p cover a nd t h e right-han d e n d pa ne l assembly o f t h e amplif ier a re easily removed fo r tran sfor mer
in st al lati on . Remo ve t h e si x fl a t head Ph ill ips sc rew s fr om t h e
t op and t w o pan head s cr ew s fr om t h e rea r fl an ge o f th e top c o v e r ,
and li ft i t o ff. T o rem ove t h e right-h and si d e panel as se mb ly , rem ov e the tw o fl a t
h ea d sc rews a t th e ri gh t e d g e o f th e fr on t p a n el , t w o at t h e e d g e
o f th e rea r p an e l, a nd t hr e e pa n he ad sc rews a t t h e ed g e o f t he
bottom pl a t e . Pul l t h e e n d panel assembly st rai ght away fr om t h e
main ch as sis assem b ly .
O ri en t th e transformer s o th at t h e tw o mu lti-pin, molded pl u gs o n
t h e transformer ha rn es s p oi n t to war d t h e fr on t o f th e am pl if ie r;
mo ve th e corr esponding mating con nectors in the amplifier it s el f
temporarily o u t o f t h e way (i t may b e necessary t o t ap e o r t i e
o n e o r both o f them o u t o f t h e way whi le insta lling t h e transfor
m er ) . Carefully sli de t h e transformer in t o position s o th at t h e
i- 20 tapped mounting ho le s i n i t s ba se li ne up with corresp onding hole s in t he ampl ifier b a s e p la t e . I nstal l t h e J- 20 bolt s an d
wa shers provided th rou gh t h e bottom p la te , an d tig ht en se curely. Check both pa ir s o f c on ne ct or s visually fo r prop er mating orienta
ti on (a v oi d ex cess ive ha rn e ss bending o r twi stin g, a s i t may c au se da ma ge t o wire s or co nnec tor p in s ) and mate them f ir m ly, pushing
until t h e integral la t c h es en g a g e.
3» Electrical Installation: If t h e amplifier i s t o b e used with t h e
t yp e o f a - c mains arr ang eme nt fo r which i t h a s be en facto ry-wir ed
( 2 20 - 2 50 V , 50- 60 Hz , 1 p h a s e, unless ot her wis e spec ifi ed) t h e en d
panel and top cover may b e re pl ac ed. I f chang e-over t o 11 0-125V
power is necessary , ma ke t h e following cha nges f i r s t : Change-Over t o 110-125V Ope rat ion - ( T he amplifier wil l op er at e
normally on 11 0- 12 5V , 5 0- 6 0 H z power i f the primary supply cir
c ui t is o f adequate cap aci ty to deliver t he required cu rrent wi th
reaso nable regulation (appro ximat ely 2 0 a mp s pe a k , 5-10 am p s aver
a ge a t full p owe r, e xc e pt PA-76C up t o 1 5 am ps av er ag e). T o
ch an ge from 220-250V to 11 0-12 5V ope ra ti on:
(a) Loca te R4 ( 2 0 0 0 o hm / 1 2 watt resistor mounted j u s t above t h e
RELAY j a c k on t h e rea r panel); install a sh or t ju m pe r of # 22
o r larg er wire acr os s i t s l u gs , shorting i t ou t.
(b) Locate th e 9 pin trans former plug P2. T h e transformer le a d
wi re originally i n t h e pin 3 position o f P 2 must be moved tc>
t he pin 2 position in t h e molded s he ll ? a l s o , th e lea d orig
inall y in th e pin 6 posi tion must b e moved t o th e pin 5 h o l e .
C AU TION! D O NOT AT TEMPT T O REMOVE THE CRIMP ED-ON PINS FR OM THE PLUG WITHOUT AN APPROPRIATE EXTRACTION TOOL A S DAMAGE T O
I
3
PIN S O R CONNECT OR I S AIMOST CERTAIN TO R ES UL T . O n r e qu e st ,
ET O will supply a t n o ch ar ge extr a push-in pin s with sh o r t
l ea d s atta ch ed . O nc e t he ampl ifier i s changed ove r fo r 1 10 -
125 vo lt op era ti on , i t i s strongly urged th at a cons pic uou s
label o r tag b e attached t o t he power cable t o avoid accidental
connection t o 220-250 volt l in e s lat er on.
Power Ca ble Conne ction - The gree n wir e of the amplifier powe r
cabl e i s a ch assi s safety gr o un d , an d must always ( a n d only) b e con nected t o th e safety ground o f t he a- c mains - - NEVER t o o n e o f t he " h o t" pow er wi re s . T he black an d whit e wi res ar e inter
ch angeable an d sho uld b e conn ected t o th e tw o " h o t " cond ucto rs
o f the se rvic e.
4. High Voltage Tap Selection: If your amplifier does not con tai n t h e high vol tage ta p cha nge relay with a fron t panel Hl/LO s w it c h,
it wa s shipped from t he factory with t h e internal HV tap co nne cted
f or ful l power SSB op er at io n. T hi s connection is als o su it able
fo r keyed CW an d for int ermit tent duty FSK or SSTV operation a t up t o o n e kilowatt d - c i n p u t. For continuous or oth erwise heavy-duty
carrier op er at io n, slightly higher efficiency and cooler ope rat ion
may b e achieved by moving th e int ernal ta p t o th e medium vo lta ge
(M V) pos it ion , a s fol lo ws: (a) DISCONNECT A-C PO W E R ; rem ove amplifier top co v er ; shor t c ro w ba r . (b) O n HV & control circuit board loc ated at ri gh t, fr ont o f t h e
chassis, n o t e sh or t loop o f blu e HV wire terminated in a fema l e
quick-connect (QC ) l u g . For normal high voltage SS B op era tio n
thi s b lu e wi re i s mated with another bl ue HV wire fro m t h e main
wiring ha rne ss ..• via t he rear-most dou ble male Q C lug o n t h e
circuit bo ard. T o connect ins tead th e medium voltage t ap , re
move on ly the fe ma le QC lug connected t o the short blu e jumper
wire and push i t fully on t o th e front-most male Q C lug (w h ic h
i s already als o connected t o a green HV wire from the harn e ss ).
No-load plate voltage will thereby be reduced from 2.4 KV (H I) t o approximately 1 .6 KV ( LO).
I t i s desirable th at you famil iarize yourself with amplifier opera
t i on , and perform initial tu ne -u p, using t h e "L O ” t a p. A c ha rt of
TUNE and LOAD con trol settings determine d under th ese condit ions
will then permit presetting the con trol s very closely when changing
frequency ther eaf ter , requiring on ly minor touch-up in o pe ra t io n.
N O TE * Use of t he optional HV tap chan ge relay permits conven ient
( a nd on-the-air le g al ) tune-up a t o n e kilowatt i np ut ; switching
then t o the HI position prepares t h e amplifier instantly fo r fu ll
power SSB operation at 2 + KW. PEP in put -- without further ad ju st men t.
5* Physical Locationt Th e ALPHA 7 6 must be located s o that in take o f
co ol air through th e rea r pan el , and exh aust of ho t air thr ough
t he top cover perf orat ions, is no t impeded in any w a y . A minimum
o f 4 t o 6 in ch es o f clea rance sh oul d b e allowed behind and ab ov e t he amplifier cabi net for air ci rcu lati on. Be careful not t o block th e top-cover exha ust op eni ng s with log books o r eq u ip me nt.
4
6. RF And Control Co nn ec ti on s : Interconnection o f the ALPHA 7 6 fo r ope ration with any pop ular transceiver o r exc it er i s ext rem ely
s i mp l e . Connect t he re ar pa nel j a ck s as fo l lo w s:
RF INPUT - Us e a sta nda rd " R CA " ty pe plug a nd RG-58C/U or similar
sm al l 50 ohm co axia l ca b le t o con nec t t o transceiver o r ex ci te r
"r f output” o r ’’a ntenna" c on ne ct or. Keep cab le sho rt i f p os si b le .
R F OUTP UT - Use a st and ard PL -25 9 ( " U H F " t y pe ) plug and RG -8A /U
o r similar 50 oh m co ax ia l ca b le to co nnect t o antenna s ys t e m .
RELAY - U se a sta nda rd "p ho no-t yp e" patch ca bl e t o conn ect t h i s
j a c k t o con tac ts wh ich a re " o p e n " o n rec eive an d "sh or te d" on
transmit (" N .O ." -- normally o p en ). Such con tacts ar e usua lly ava ilable on t h e re ar pa nel o f th e exciter o r transceiver i n t h e form o f a matching " p ho n o" co nn ec to r. A few trans ceiv ers, su c h
a s Atl as and Dr ake uni*t^ may require spe cial conn ectors fo r tying in to their in te rn al transmit- receive relay co nta ct s.
NOTE: When t h e amplif ier is OF F o r i n th e RECEIVE condition with
n o shor t acros s t h e RELAY l i ne , th e RF OU TPU T connector is inter nally
connected directly t o t he RF INPUT co nn ec to r, providing n ormal
"transc eive-ty pe" an te nna in p ut t o t he re ce iv er .
A LC - For use with convent iona l transceivers having neg ative-
going AL C sy st em s, simply patch t his j a c k t o t he mating AL C j a c k o n t h e transceiver (o r ex c it er ) , using standard "phono” c a b l e .
Certain solid-state tra nsc eiv ers utilize positive-going A LC which re quir es slig ht modification o f th e ampl ifier's ALC ci r cui t, o r u s e o f an ad ap te r, i f AL C feedbac k is t o b e em pl oy ed . Normally i t i s quite satisfactory t o simply u se t he transce iver's int er nal
AL C system with A t la s , Tr i to n , and similar ra dio s.
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