Mechanics & Electronics ME750-FD Operating Manual Download Page 11

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5.6    ALWAYS THINK -  SAFETY 

 

THIS LINEAR AMPLIFIER DESCRIBED IN THIS MANUAL CONTAINS VOLTAGE HAZARDOUS TO 
HUMAN LIFE AND SAFETY WHICH IS CAPABLE OF INFLICTING PERSONAL INJURY. NEVER 
OPERATE THE AMPLIFIER WITH THE TOP COVER REMOVED AND THE TOP COVER SAFETY 
SWITCH DEFEATED. BEFORE REMOVING THE TOP COVER MAKE SURE THE AC LINE POWER 
CORD HAS BEEN DISCONNECTED FROM THE AC POWER SOURCE. ALLOW A MINIMUM OF 5 
MINUTES TO ELAPSE BEFORE REMOVING THE TOP COVER AFTER POWER HAS BEEN 
REMOVED. THIS IS NECESSARY TO ALLOW THE PLATE VOLTAGE FILTER CAPACITORS TO 
BLEED DOWN TO A SAFE LEVEL. 
 

Before operating this unit ensure that the protection conductor (green/yellow wire) is 
connected to the ground (earth) protective conductor of the power outlet. Do not defeat the 
protective features of the third protective conductor in the power cord by using a two 
conductor extension cord or a three-prong/two-prong adapter. 

 
Before operating this unit: 
 

1. Ensure that the instrument is configured to operate on the voltage available at the power 

source. (See Installation Section) 

 

2. Ensure that the proper fuses are in place in the amplifier's AC line fuse holders located 

 

on the rear panel. 

 

3. Ensure that all other devices connected to or in proximity to this amplifier are properly 

 

grounded or connected to the protective third-wire earth ground. 

 

If at any time the amplifier shows visible damage, has sustained stress, emits a foul smell, 
fails to operate satisfactorily, it should not be used until its performance has been checked 
by qualified service personnel. 

 

Connect a good earth or water pipe ground to the ground post on the rear of the Amplifier. Use 
the heaviest and shortest connection possible. Before you use a water pipe ground, inspect the 
connections around your water meter and make sure that no plastic or rubber hose 
connections are used. These connections interrupt the continuity to the water supply line. 
Install a jumper around any insulating water connectors you may find. Use heavy copper wire 
and pipe clamps. 
It is best to ground all equipment to one point at the operating position and then ground this 
point as described above. 
 

5.7 SAFETY INTERLOCK SWITCH 

 

While the Amplifier's top cover is in place, the interlock switch closes to allow AC line voltage to reach 
the power transformer. When the top cover is removed, the interlock switch opens and disconnects the 
line voltage. This does not discharge the bank of power supply filter capacitors. Be sure to allow the 
filter capacitors to discharge before you touch anything inside the Amplifier. You can select the High 
Voltage function of the Multimeter to check the high voltage potential. 
 

Summary of Contents for ME750-FD

Page 1: ...RATING MANUAL ME750 FD 4 6m LINEAR AMPLIFIER 2XGI7BT LED BARGRAPH VERSION Mechanics Electronics Inc Hungary Draskovits Gábor HA1YA Szombathely Kárpáti K u 43 H 9700 e mail ha1ya chello hu www ha1ya hu M E ...

Page 2: ...2 C O N T E N T 1 0 General overview 3 2 0 Specifications 5 3 a Front Panel 6 3 b Rear Panel 8 4 0 Installation 9 5 0 Troubleshooting 10 6 0 Drawings 12 ...

Page 3: ...ly activating the protection of the Linear In case of lately designed equipment the output power of the TCVR is control of the radio 1 2 The SWR protection of the Linear is inactive during STBY mode In case the SWR 1 3 in QRO mode the protection is active the PA can be use only with Antenna Tuner 1 3 The required power supply is 230V 50Hz according to the EU standard Verify that the rating of the ...

Page 4: ... temp SWR 3 Temperature dependent ventilating speed control Cooling fans 2 pcs Function and status indicator LEDs 6 pcs 1 8KVA transformer 3 way PIC controlled sequencer 4 LED bargraph on new front page version PWR out VSWR Ig Ia ...

Page 5: ...s common outp Driving Power 0 50W max on both bands Input WSVR max 1 1 5 on both bands In Out impedance 50 Ohm separate input bands Valve s 2XGI7BT T R System SEQUENCER OPEN COLL OK Harmonic supression 50dB at 700W RF out Intermodulation 35dB at 700W RF out Protection Ia 1 0A Ig1 250mA VSWR 3 Temp 75C o Dimension 410X185X300 mm Weight 25kg Mains 220 230V 10A 50 60 Hz ...

Page 6: ... the PA 5 OPR LED Glows when the PA is ready for transmission During heating up period when the LED doesn t lit the driving is blocked The stby time is about 180 sec 6 WAIT LED Blinking during the heating up period indicating that the heating is in progress Required time is abt 180 sec when the light goes out and the OPR led lit up 7 QRO LED Indicates the high power mode of the PA Can be activated...

Page 7: ...d knobs Tuning knobs of the anode and antenna side capacitor Used for tuning the PA for max output The position of the capacitors is different on 4m an 6m 14 4 6m SWITCH Switching the input output of the PA to 4m 6m For QRP mode must switch to real band If you use bypass mode on 4m switch it to 4m if on 6m switch it to 6m ...

Page 8: ...former 12V 0 2A DC 6 FAN 2 Cooling fan for the power valves 12 18V 0 3A DC or 230V AC 18W 7 PTT Connection for PTT RCA The relays are closed by earth connection Low voltage low current entry Fit for open collector control as well 8 INPUT Input connection for the driver TCVR 50 Ohm N connectors on both bands the 6m input is on the center position 9 OUTPUT Aerial connection 50 Ohm Common ant connect...

Page 9: ...ut of use for a longer period 2 3 month it would be advisable to keep the PA heated without driving for a few hours 4 6 When the OPR LED is light push on the OPR switch The PA is ready to work Don t forget choose the wanted band with the 4 6m bandswitch 4 7 Using the tuning mode of the TCVR CW give driving power to reach 200 400 mA indication on the Ip bargraph Tune for maximal output power with P...

Page 10: ...V is indicated on the Ip bargraph Possible HV circuit fault check the F3 fuse 1A on rear panel HV sampling resistor in power supply damaged HV panel R23 0 47 Ohm No idle current when you push the PTT about 120 mA on the Ip bargraph Not Ua voltage Push the red HV knob If anode voltage is missing check F3 HV fuse 1 A fuse on rear panel The idle current is too low or too high you can set the needed v...

Page 11: ...oximity to this amplifier are properly grounded or connected to the protective third wire earth ground If at any time the amplifier shows visible damage has sustained stress emits a foul smell fails to operate satisfactorily it should not be used until its performance has been checked by qualified service personnel Connect a good earth or water pipe ground to the ground post on the rear of the Amp...

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