Power Amplifier on GU-43B Manual

Using of Amplifier is only by special agreement with Alex !!! 

Please carefully read the following text to the end with full concentration before you start to do any operation! 

After that go step by step paying  attention  to every phrase!


Connect AC cable (white socket) to 230VAC mains under the table and connect the 3-phase socket of the Power Amplifier (PA) to corresponding 3-phase AC outlet (s.next pic).

It is not necessary to push any buttons or activate any switches in the PA under the table itself. Don’t touch the PA, please – it might cause damage!


This is RCU  (remote control unit on the table):

On the RCU you may choose one of four modes:

1 OFF Activate OFF mode
2 FAN In the Bypass mode the fan is working, bias voltage feed is switched ON, there is no screen voltage on the tube and no relay switching voltage. This mode is used for cooling of the tube during switching OFF while there is no filament voltage.
3 STB Standby mode. Filament voltage is fed to the tube. Otherwise everything is just the same as in point 2. In this mode PA continues to work in Bypass mode.
4 ON

Operate mode

Switching ON

Before switching the PA «ON» the tube must be heated minimum for two (2) minutes in the STB mode.

Switching OFF

Like a diesel turbine - PA should work after the engine stops :

  1. Switch the PA to the mode STB for two (2) minutes
  2. Switch the PA to the mode FAN to cool the tube for min. two (2) minutes
  3. After two (2) minutes switch the PA to the OFF mode.


HF Drive power from exciter to the PA must be no more than 20 W (20% at Icom 7300)  on the 80, 40, 20 meter bands and no more than 10W (10% at Icom 7300)   on the 160, 15 and 10 meter bands (see next picture):

Band switching

All bands are pretuned to the corresponding antennas. To switch to the desired band you must:

-        choose the band on the Radio ;

-        make sure you have selected the correct ANT;

-        choose the band on the RCU and after that briefly push this black button on the RCU (see next picture):

Switching is automatic. When the STB led switches OFF, switching to an other band is done and the PA is ready for operation. 

If STB led is not turning OFF, try to push the black button once more.

Do not switch the bands too fast. 15 seconds after starting last band switching you should not switch to a new band. 

Led “АВАРИЯ” is switched ON

In case of High Voltage (HV) or Screen Current (SCREEN) protection the light emitting diode (Led) «Авария» (ALARM) on the RCU is switched ON.

To switch the protection off you have to go to the mode STB and then back again to the mode ON. If the protection is activated once more, you must find the reason for this and solve it. The reason may be a mismatch of the antenna or excess HF drive power from the exciter (radio).

Please pay attention to the following points:

Download PDF