DRAKE HCP2550A Instruction Manual - Page 7

Browse online or download pdf Instruction Manual for Computer Hardware DRAKE HCP2550A. DRAKE HCP2550A 16 pages. Commercial heterodyne channel processor (for use in ntsc systems)

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Front Panel Controls and Indicators, continued

F5 – INPUT CHANNEL Number Switch

Sets the input channel number for off-air TV channels 02

through 69, for standard CATV channels 02 through 125,

or IRC, HRC* channels 01 through 125. See also Item F4

which sets the type of channel (off-air or various types of

CATV channel plans) and sets the leading "1" for CATV

channels 100 through 125.

*HRC – Harmonically Related Carrier

*IRC – Incrementally Related Carrier

F6 – LOCK DETECT Indicator

Lights to indicate that both input signal synthesizers are

locked. Additionally, if the 'AFC' switch is on, this LED

lights to indicate that the AFC is locked. If this indicator is

off, check for 'Channel Plan' switch settings that are

consistent with the type of input signal that is supplied to

the HCP2550A.

F7 – SIGNAL Indicator

Lights to indicate that an input signal is being received as

set by the input channel switches and has a signal

strength greater than the PILOT THRESHOLD setting.

F8 – PILOT THRESHOLD Control

When enabled by the rear panel 'PILOT' switch, the

setting of this control determines the input signal level

threshold at which an internal visual carrier is generated

to replace the (missing) input signal carrier. This feature

provides full black screen video and muted audio at a

connected TV receiver in the absence of, or below

threshold level, input signal. This threshold level is

reduced approximately 10 dB if the input preamp is

switched on (see Item F2).

F9 – A/V RATIO Control

This screwdriver adjustment varies the level of the output

aural carrier over a range from +5 to –12 dB relative to the

input A/V ratio. The aural carrier should be adjusted to

approximately 15 dB below the visual carrier (normal

operation). Clockwise rotation increases the output aural

carrier level and thus decreases the output A/V ratio.

F10 – OUTPUT LEVEL Control

This screwdriver adjustment varies the RF OUTPUT level.

Clockwise rotation increases the level.

F11 – OUTPUT ENABLED Indicator

Lights to indicate that a valid channel is selected.

The RF output is switched off for any invalid output

channel settings.

F12 – OUTPUT CHANNEL Number Switch

Sets the output channel number for standard CATV

channels 02 through 78 and 95 through 99. Note that

these switches set the output frequency for a visual carrier

frequency of 'xx.25' or 'xxx.25' MHz along with any

required FCC offset for shared aviation/navigation

frequencies. See Table 2 – "OUTPUT CHANNEL"

included in this manual for the list of corresponding

operating frequency, and offset, if any, for each channel

number. It is important to note, however, that the output

frequency is accurate only if the input signal is on a proper

frequency (includes any offset, plus or minus, if required)

or the AFC function is active and locked. It is

recommended that the AFC (see Item F3) be switched

on for all combinations of input and output channels,

except when the output channel is set for the same

channel as the input.