AOR AR5000 User Manual download pdf (Page 21)

AR5000 OPERATING MANUAL PAGE 21

Select receive bandwidth: For point-to-point

communications a bandwidth of 15 kHz usually provides

best results, however if adjacent channel interference is

experienced a bandwidth of 6 kHz may provide better

results. Press

o access the I.F. bandwidth

menu then use the SUB DIAL to make the selection (in this

example select 15 kHz). Press

to accept the

selection and return to VFO mode.

If the MAIN DIAL is rotated the frequency will increment in

10 kHz steps but the trailing 1.25 kHz will remain in place...

27.60125 MHz, 27.61125 MHz, 27.62125 MHz etc.

The trailing digits will not be set to zero enabling tracking

of unusual band plans.

The

MAIN DIAL

follows the adjusted frequency

bandplan while the

SUB DIAL

kills the trailing digits

and steps rigorously in round numbers.

To cancel step-adjust

The easiest way to cancel step-adjust is to return to

AUTOMODE, press and hold the

key for more

than one second. Step-adjust will be cancelled and the

frequency will hop to the nearest whole increment as

determined by the automode bandplan data.

You may also cancel step-adjust using the STEP MENU.

Press

to activate the step menu. If step-adjust is

active, the legend “*” will be displayed on the left of the

LCD. Press

to toggle the step-adjust facility On/

Off. To accept the change to OFF, press

to return

to VFO mode.

Another example:

If the frequencies you need to search are allocated as:

145.210 145.224 145.238 145.252 145.266 145.280

145.294 145.308

Check the stepping size at first:

145.224 - 145.210 = 0.014 STEP SIZE

To enter this step size and data using the

easiest

method!

First key in the start frequency while in VFO mode:

Select the step menu by pressing

Key in the required step size:

Select

step-adjust

by pressing the key, the legend

“*” appears on the left of the LCD to confirm selection.

Complete the entry by pressing

The MAIN DIAL will now tune the receiver in 14 kHz steps

with the trailing offset maintained. The SUB DIAL tunes the

receiver in 14 kHz steps but clears the offset to a round

number (i.e. zero).

Note: You may review the step-adjust value quite simply...

While in VFO mode, press

followed by

access the step-adjust sub menu. In the above example

the step-adjust value will be 2.0 kHz, refer to the following

text for the mathematical explanation...

this is not

essential but makes good bedtime reading!!!

Application of arithmetic for the step-adjust

For those who wish further information on the

mathematics involved... the AR5000 works this out for

you automatically! The following examples should explain

how the step-adjust works in theory.

If the frequencies you need to search are allocated as:

145.210 145.224 145.238 145.252 145.266 145.280

145.294 145.308 (MHz)

Check the stepping size at first:

145.224 - 145.210 = 0.014 STEP SIZE (MHz)

Now you have found that each frequency is allocated

with a 0.014 MHz (14kHz) spacing you now have to

calculate the value of the internal processing frequency:

145.210 / 0.014 = 10372.14285

This should be rounded as 10372 INTERNAL

PROCESSING VALUE

To obtain the internal processing frequency, multiply the

STEP SIZE by the INTERNAL PROCESSING VALUE:

0.014 x 10372 = 145.208 INTERNAL PROCESSING

FREQUENCY (in MHz).

Now calculate the STEP-ADJUST VALUE by subtracting

the INTERNAL PROCESSING FREQUENCY from the

DESIRED FREQUENCY:

145.210 - 145.208 = 0.002 (MHz) = 2 kHz

STEP-ADJUST VALUE

It can be concluded that a step-adjust value of 2 kHz is

required.

In order to step through the above frequency

allocation you need to apply a STEP SIZE OF 14 kHz

with a 2 kHz STEP-ADJUST.

To apply a step size of 14 kHz and step-adjust of 2kHz:

Select VFO mode by pressing

, select the desired

VFO (displayed in the right hand lower corner of the LCD).

Press

to activate the STEP select menu.

Press

to select STEP-ADJUST. The legend

“*” will appear on the left of the display to confirm selection

of step-adjust.

Key in the required step size for tuning (14 kHz in this

example) by pressing

Press the

key to select the step-adjust entry menu.

The “STEP-ADJ” legend will flash in the middle of the

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AOR AR5000 User Manual Page 21

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