1 7
N O T E
Appearance of an arrow on either left or right TRI scale edges means
that the LOAD knob is too far from the proper position. To correct
this, turn the LOAD knob to the prompted direction until the triangle
marker appears inside the scale field.
I
_____
!
_____
IIII
> ____
!
_____
IIIIIIIIIII
_____
!
____<
IIIIIII
_____
!
__v___
IIIIIIIIIIIIIIII
_____
v
_____
no marker:
use TUNE knob for
max. P to get any
marker.
marker is a far left:
turn LOAD knob
pointer to right until
marker inside.
marker is a far right:
turn LOAD knob
pointer to left until
marker inside.
marker inside:
turn LOAD knob
slightly left to
center it.
LOAD is tuned:
turn TUNE knob to
peak Forward
Power & finish.
Fig. 4-I. Using TRI tuning aid
Please note also, that the TRI mark will not appear until at least 5W drive is applied, and at
least 20W forward power is achieved.
If, for some reason, matching cannot be accomplished successfully, check the
BAND switch
position and proper antenna selection. Then check the antenna VSWR at the same drive
frequency.
d) Tuning hints.
While turning the
knobs, you'll note that both tunings would be virtually independent. This is
a benefit of the TRI. The plate-load resistance increases to the right and decreases to the left
of the TRI center.
The
scale center corresponds to the proper LOAD capacitor tuning, which presents an
optimum load resistance to the tube.
If you tune to the right, you'll obtain more gain, but less undistorted output power will be
attainable. You may prefer to use this hint when your drive power is insufficient or when you
need less output but better efficiency, for instance at heavy duty modes (RTTY, SSTV etc)
where less heat is wanted (not only in the amplifier but also in the transceiver).
Tuning to the left of the center would lead to the opposite: less gain and more power
attainable. Of course, this requires more drive power, more plate current, and more plate
heat, which shortens tube's- expected life, as its cathode would be faster exhausted.
You might use the off-center tuning hint also to compensate for mains voltage variations in
order to maintain tube efficiency: tune to the right when mains is higher, or tune to the left if
it's lower than the nominal voltage. Please see S.2-2 (Line Voltage Selection) for more than
5% difference from the nominal.
4-5. ON LINE Information Screens and Control Functions.
a)
Besides the Warming Up and TRI (described above in S.4-1, S.4-3 and S.4-4), you have 12
more Information screens available. They are as follows: Forward Power, Reflected Power,
Output Power (difference between forward and reflected), Antenna VSWR, Drive RF Power, RF
Power Gain, Plate Current, High Voltage, Plate RF Peak, Screen Current, DC Power Input
(product of plate current and high voltage), and Exhaust Air Temperature (Celsius and
Fahrenheit scales). You can use them to monitor the technical state of the amplifier and the
associated parameters in a digital form.
Selection is made by the PREV and NEXT buttons. You may change them in a closed loop,
while the amplifier is used and controlled in operate and standby modes, changes transmit
and receive, without any influence by the measurement process.
Summary of Contents for 1500
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