Specifications

12
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 “V”-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.
N O T E
Appearance of an arrow on either the left or right TRI scale edges means that the LOAD knob is too far from
the proper position. To correct for this, turn the LOAD knob to the prompted direction until the “V”-marker
appears inside the scale field. Then center it.
i iiii iiiiiiiii iiiiii iiiiiiiiiiiiii
-----!----- >----!----- -----!----< -----!---v- -----v-----
no marker: marker is far left: marker is far right: marker inside: LOAD is tuned:
use TUNE knob turn LOAD knob turn LOAD knob turn LOAD knob turn TUNE knob
for max.P pointer to the right pointer to the left slightly to the left to peak Forward
to get any marker until marker is inside until marker is inside to center it Power & finish.
Fig.4-1. 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 antenna selection and VSWR at
same drive frequency.
d) Tuning hints.
While rotating 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 center of the scale 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.
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 10% difference from the nominal.
4-4. "ON LINE" Information Screens and Control Functions.
a) Besides the Warming Up and TRI (described above in S.4-1 through S.4-3), 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