Acom 1500, Руководство пользователя, Страница: 16 / 25

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We recommend that you tune-up at the center frequencies of the preferred frequency band.
First select the band switch and the correct antenna number (never with RF applied!). Then
use table 4-I in order to achieve an approximate preset for both TUNE capacitor and LOAD
capacitor knobs:
Band, MH z Tune Knob Dial Load Knob Dial
1.8 - 2 62 - 30 65 - 38
3.5 - 4 59 - 40 72 - 53
7 - 7.3 57 - 55 65 - 60
10.1 - 10.2 15 - 14 27 - 26
14 - 14.35 60 - 50 32 - 30
18 - 18.2 70 - 68 67 - 65
21 - 21.45 19 - 15 47 - 44
24.9 - 25 67 - 66 60 - 59
28 - 29.7 26 - 12 46 - 39
50 - 54 32 - 13 24 - 20
Table 4-I. Approximate tuning presets
b) Selecting the plate-load True Resistance Indicator (TRI) tuning aid.
You may select TRI scale in three different ways:
-
By pressing simultaneously the PREV+NEXT buttons shortly. This will insert a 6dB
attenuator between the driver and the amplifier's input (the ATT LED will light), so you'll not
need to reduce the drive power during tuning. Press PREV+NEXT buttons momentarily again
to switch the attenuator off the input and to return to the old screen. If you use any of PREV
or NEXT buttons only, the attenuator would be switched off too, but the information screen
would change to respectively previous or next.
-
By pressing repeatedly either PREV or NEXT button (whichever is nearest), until you reach
the TRI scale. This will not insert the attenuator, so you'll have to use less than 20W drive
(unless the amplifier is near correct tuning), otherwise the next step would be executed
automatically:
-
By simply applying a normal working (60-85W) drive power, while the amplifier is not yet
tuned. This will automatically invoke the TRI tuning aid and will insert the input attenuator
(the ATT LED will light) after one second. The attenuator will be switched off, and the old
screen will be returned automatically, after you release the PTT shortly. If you have achieved
meanwhile a nearly good tuning, the attenuator would not be inserted again. If the old screen
was the same (TRI, selected manually earlier), you'll then be able to precisely tune the
amplifier also at nominal power, without changing drive at all. Use this hint to shorten the
tuning process duration.
c) Tuning Procedure.
While a continuous (CW) signal at the desired frequency is still applied:
-
Look at the upper scale (forward power); obtain maximum power using the upper (TUNE)
knob;
-
Look at the lower (Load Cap) scale and turn the lower (LOAD) knob in order to center the
triangle marker at the "!" mark.
-
Release the PTT shortly in order to disable the attenuator, then repeat both steps at
nominal power. - Always finish by peaking with the TUNE knob.