Assembly Instructions

835A 4 kW, 5 kW or 6 kW UHF Transmitter Site Considerations
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2. Do not have the air conditioner blowing directly onto the Transmitter. Condensation may occur on, or worse, in the
Transmitter under certain conditions.
3. Do not isolate the front of the Transmitter from the back with the thought of air conditioning the front only. Cooling
air is drawn in the front of all Transmitters and in the front and back of others. Any attempt to isolate the front from
the rear will adversely affect the cooling air flow.
4. Interlocking the Transmitter with the air conditioner is recommended to preclude operation of the Transmitter without
the necessary cooling.
5. The periodic cleaning of all filters is a must.
When using ventilation alone, the following general statements apply.
1. The Blower with attendant filters should be on the inlet, thereby pressurizing the room which prevents the ingress of
dirt.
2. The inlet and outlet should be on the same side of the building, preferably the leeward side. The pressure differential
created by wind will be minimized. Only the outlet may be through the roof.
3. The inlet and outlet should be screened with 1/8" hardware cloth (preferred), galvanized hardware cloth (acceptable).
4. Cooling air should enter the room as low as practical but in no case higher than four feet above the floor. The inlet
must be located where dirt, leaves, snow, etc. will not be carried in with the cooling air.
5. The exhaust should be located as high as possible. Some ducting is usually required to insure complete flushing of
heated air with no stagnant areas.
6. The filter area must be adequate to insure a maximum air velocity of 300 feet per minute through the filter. This is not
a conservative number but a never exceed number. In a dusty or remote location, this number should be reduced to
150 CFM.
7. The inlet and outlet(s) must have automatic dampers that close any time the ventilation blower is Off.
8. Where Transmitters are regularly Off for a portion of each day, a temperature differential sensor controlling a small
heater must be installed. This sensor will monitor inside and outside temperatures simultaneously. If the inside
temperature falls to within 5° F of the outside temperature the heater will come On. This will prevent condensation
when the ventilation blower comes On and applies even in the summer.
9. A controlled air bypass system must be installed to prevent the temperature in the room from falling below 40° F
during Transmitter operation.
10. The blower should have two speeds, which are thermostatically controlled, and interlocked with the Transmitter.
11. The blower on high speed must be capable of moving the required volume of air into a half inch of water pressure at
the required elevation. The free air delivery method must not be used.
12. Regular maintenance of the filters if present can not be overemphasized.
13. Tube Transmitters should not rely on the internal blower for exhausting cooling air at elevations above 4000 feet. For
external venting, the air vent on the cabinet top must be increased to an 8" diameter for a 1 kW Transmitter and to 10"
for 4, 5 kW, 6 kW & 10 kW Transmitters. An equivalent rectangular duct may be used but in all cases the outlet must
be increased in area by 50 % through the outlet screen.
14. It is recommended that a site plan be submitted to Axcera for comment before installation commences.