User's Manual
8 3 6 A 2 k W UHF Tr a nslat or , I nt erna lly Diple x ed Sit e Con sider a t ions
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There are special considerat ions t hat need t o be m ade before inst alling the 836A and this sect ion
will help you plan ahead.
The Translator requires an AC I nput Line of 220 VAC wit h a rat ing of 80 Am ps. Check that the site
has t he volt age requirem ent needed.
836A is designed and built t o provide long life wit h a m inim um of m aint enance. The environm ent in
which it is placed is im portant and certain precautions m ust be t aken. The t hree greatest dangers
to your Translator are heat , dirt and m oist ure. Heat is usually t he great est problem , followed by
dirt and then m oist ure. Over-t em perat ure can cause heat relat ed problem s such as therm al
runaway and com ponent failure. Each Am plifier Tray in the Translat or contains a Therm al I nt erlock
Prot ection Circuit t hat will shut down that Tray until t he t em perat ure drops t o an accept able level.
To begin t o design a suit able environm ent for your new Translat or it is im perat ive that you
understand what an " I deal Environm ent " is and how it can enhance t he overall perform ance and
reliabilit y of your Translat or, thereby m axim izing revenues by m inim izing down t im e. A properly
designed facilit y will have an adequat e supply of cool clean air, free of airborne particulat es of any
kind, and wit hout excessive hum idit y. An I deal Environm ent will require t em perature in t he range
of 40 degrees F t o 70 degrees F year round, reasonably low hum idit y and a dust free room . I t
should be not ed t hat t his is rarely if ever at t ainable in the real world. However, the closer your
environm ent is t o t he I deal Environm ent t he greater t he operat ional elevat ion. A heat related
problem m ay not surface for m any m onths if t he installat ion is com plet ed during cool weather, but
m ay suddenly appear during the heat of sum m er.
The fans and blowers designed and built int o your Translat or will rem ove t he heat from wit hin the
cabinet but addit ional m eans is required for rem oving this heat from the building. I n doing this a
few considerat ions should be noted. The first st ep is to determ ine t he am ount of heat t o be
rem oved. There are generally t hree sources of heat t hat m ust be considered. The first and m ost
obvious is t he heat from the 2 kW Translator it self. This can readily be det erm ined by subtract ing
the Average Power t o the Ant enna ( 1290 Watt s) from the AC I nput Power ( 8000 W) . These
num bers will be different for t he 5 kW and 10 kW Translat or but can be found by referring to t he
published lit erat ure or direct ly from Axcera. This num ber in Wat t s ( 6710) is then m ult iplied by 3.41
which gives ( 22881.1) t he BTU's t o be rem oved every hour. 12,000 BTU's per hour equals one ton,
so a t wo- t on air condit ioner will cool a 2 kW Translator. The second source of heat is other
equipm ent in the sam e room . Calculat e t his num ber as you did above. The t hird source of heat is
equally obvious but not as sim ple t o calculat e. This is the heat com ing t hrough t he walls, roof and
windows on a hot sum m er day. Unless the underside is exposed, t he floor is usually not a problem .
Determ ining this num ber is usually best left up to a qualified HVAC Technician. There are far t oo
m any variables t o even estim at e t his num ber without det ailed drawings of the site showing all
const ruct ion det ails. The sum of these t hree sources is t he t ot al am ount of heat that m ust be
rem oved. There m ay be ot her sources of heat , such as personnel, and all should be t aken into
account.
Now t hat you know t he am ount of heat that m ust be rem oved we will consider how t his can be
accom plished. Your opt ions are air condit ioning, vent ilation or a com bination of the two. Air
condit ioning is always the preferred m et hod and is the only way t o approach the I deal
Environm ent .
Ventilat ion will work quit e well if t he am bient air t em perature will be below 100 degrees F or about
38 degrees C and the hum idit y should be at a reasonable level. I n addit ion, t he air stream m ust be
adequat ely filt ered t o ensure t hat no airborne particulat e of any kind will be carried into the
Translat or. The com bination of air condit ioning for sum m er and ventilation during the cooler
m ont hs is acceptable when the proper cooling cannot be obt ained t hrough t he use of ventilat ion
alone and air condit ioning year round is not feasible for what ever reason. However, opera t ion of
air con dit ioning a nd vent ilat ion sim ult a neou sly is n ot re com m e nded because t his can cause