Print Date 04/01/11 Page 29 of 42 E2165-00MA-04
10) The channel frequencies (seven total) are stored in non-volatile ‘flash’ memory and are thus
retained whilst power is removed. To load the frequency, entered in Channel 0, into one of the
seven stored channels, press the left hand [
∧
] and [
∨
] keys as required to obtain the
destination Channel number display. The presently selected channel (for transmission) will
indicate ‘(int. selected)’ or ‘(ext selected)’ the other six will indicate ‘(stored frequency)’ as well
as ‘Select’ and ‘Update’ above the extreme left and right hand [soft keys].
11) The frequency in channel 0 can only be loaded into one of the six channels by pressing the
[soft key] below ‘Update’. The seventh, presently selected, channel cannot be over-written
with a new frequency. To do this, first select another channel for transmission by pressing the
[soft key] below ‘Select’ when its’ screen is displayed. This will ‘free’ the previously transmitted
channel for a frequency update (note the comments in section 2.3.5 about locked channels).
12) It is recommended that if only one frequency is required, then that frequency should be loaded
into all seven channels. If required however, a channel can be cleared by updating it with
‘……MHz’ from channel 0. If selected for transmission a cleared channel will produce a muted
output (although the Exciter will ‘rest’ at 98MHz).
13) If not already selected, select the channel required for transmission by pressing the [soft key]
below ‘Select’ when its’ screen is displayed. The display will show ‘(int. selected)’. Press
[MAIN] to return to the main screen which will show the selected channel and its’ frequency.
14) Reconnect the rear panel Interlock connection between pins 20 and 21 of SK12
15) Turn the Front Panel POWER control clockwise to increase the selected Exciter’s output
power until the required ‘Fwd’ power is obtained, as indicated on the LCD display The
displayed ‘Rev’ power depends on the return loss of the load presented to the Exciter’s RF
output but should generally be less than one twentieth of the ‘Fwd’. To ensure complete
accuracy, an external calibrated power meter should be used to measure the ’Fwd’ output
power.
The Exciter will now be ready for operation with audio and or data sources applied to the rear panel
inputs, the instantaneous deviation being displayed on the main screen bargraph. Input levels or the
corresponding rear panel sensitivity controls may need adjusting to obtain the required deviation. Note
that when the /S Stereo Encoder option is fitted, its Limiter and Clipper functions (on or off) will affect
the deviation levels obtained from the Left/Right or digital AES inputs.
The Front Panel RF MON output can be used to check the close-in spectrum of the Exciter output
signal, noting that any harmonic levels shown will not necessarily be the same as those present at the
Exciter output. The Front Panel BASEBAND MON output can similarly be used to check the spectrum
of the final modulating signal. Any test equipment should not however normally be left connected to
these two outputs.
2.3.4 Channel and Frequency Selection and Setting During Operation
Channel frequencies may be loaded or altered whilst the Exciter is operating, delivering output power,
as detailed in section 2.3.3, steps (8) to (11). The frequency of the channel on which the Exciter is
operating however, cannot be altered, this channel frequency display showing ‘(int. selected’) or ‘(ext
selected)’ see step (10).
To change the operating channel, press [MODE] on the front panel keyboard, then the [soft key] under
‘Freq.’, then the left hand [
∧
] and [
∨
] keys as required to obtain the channel and frequency required,
and finally, the [soft key] below ‘Select’ (note ‘Select’ will not appear on special channel 0 or on the
channel already selected). Note also the comments in section 2.3.5 about locked channels.
The front panel SYSTEM NORMAL LED will show red until the new frequency is ‘in lock’, this taking
several seconds. After a total of about 12 seconds, RF will be output at the new frequency. However, if
the frequency is ‘……MHz’ (the clear channel) the output will remain muted. Press [MAIN] to confirm
operating channel and frequency.