Elenos T25000, Handbook

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Hand Book T25000 -
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OPERATIONAL LIMITS
The T25000 power amplifier can function at full power if the ambient conditions fall within the limits
defined in the chapter entitled "First Phase of Installation". The maximum altitude of the installation
must not exceed 2000m above sea level to guarantee maximum RF power output. If the altitude of the
installation does exceed 2000m, the specified RF power output must be reduced, also in correlation
with the ambient temperature. The limits of the working output power in this case have to be found
experimentally, the performance of the unit is not readily definable under these conditions. It is not
however possible for the equipment to conform to conditions of safety and the guarantee if the site has
an atmospheric pressure equivalent to an altitude in excess of 3500 m above sea level. The ambient
humidity is very important in relation to the high voltage circuits; a value of up to 95% can be
tolerated at a temperature of 45°C, but only if variations in atmospheric pressure do not provoke
condensation. The equipment cannot function under any condition if the ambient humidity is
condensing. If fluctuations in line voltage are very large, the whole system should be adjusted taking
account that the RF power output can exceed the safety limits of the equipment or the radiating system.
If the only unit dependant on line voltage is the T25000, the voltage/power characteristics are as
follows:
A 2% variation of line voltage implies a 5% variation of RF power output
A 5% variation of line voltage implies a 15% variation of RF power output
A 10% variation of line voltage implies a 25% variation of RF power output
The equipment will not operate however if line voltage exceeds 15% of nominal or is 20% less than
nominal. The thermionic tube is subject to wear through use. After a year of operation, the
performance of the T25000 will most certainly have been degraded, but not necessarily terminated.
The thermionic tube must be changed when the gain of the amplifier falls below 9dB.
The radiating system must present an electrical impedance of 50
Ω
. The T25000 amplifier can function
normally if the standing wave ratio (S.W.R. or R.O.S) is less than 1.6. When the radiating system
exceeds this figure permanently, it is possible for the protection mechanism to trigger due to standing
waves. Operation at reduced power levels is useful to avoid loss of service but does not guarantee that,
due to variations of electrical or ambient conditions, loss of service will be avoided.