Mechanics & Electronics ME3000-V User manual

ME3000-V
2M LINEAR AMPLIFIER
GU78B
Mechanics & Electronics Inc. Hungary
Draskovits Gábor HA1YA Szombathely, Kárpáti K. u. 43. H-9700
e-mail: [email protected] [e-mail]

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CONTENT
1.0 General overview.................................................................2
2.0 Specifications ......................................................................4
3.0 Technical description..........................................................5
3./a Front Panel...........................................................................6
3./b Rear Panel............................................................................8
4.0 Installation ...........................................................................9
5.0 Troubleshooting ................................................................10
6.0 Drawings ............................................................................13

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ATTENTION!
Please read this manual carefully before operating the equipment!
The Linear Amplifier is easy to use, and damages can be avoided by following the
instructions stated below. Incorrect use may cause the loss of warranty.
1.0 G E N E R A L O V E R W I E W
The Linear Amplifier is produced by M+E Mechanics & Electronics Inc.
During the design of the ME series , the main point was to construct Linear Amplifiers for HF, VHF,
and UHF amateur bands with similar mechanical measures and appearance ,using ceramic valves
easily available on the market.
The ME 2500and 3000-V utilises the advantage of the valve GU84B and GU78B, and considering the
power output and price, is a worthy competitor of similar equipment on the market.
The Amplifiers are protected by modern circuits,-specially designed and used only by our
company,-providing a very high level of protection. With their low input power and high efficiency
they fulfil the requirement of an improved amateur station.
To use the Amplifier with satisfaction and utilising all it’s advantages ,please read the following
general instructions carefully:
1.1 Do not use higher driving power as given in the instruction manual. During SSB transmission the
‘MIC GAIN’ control of the TCVR is not fit for the TCVR is regularly 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 VSWR > 1:2 in QRO mode, the protection is active.
1.3 The required power supply input is 230V 50/60 Hz or 400V 50/60 Hz between two phase
according to the EU standard. Verify that the rating of the line fuses located in the rear panel of
power supply in fuse holders is suitable for the AC line voltage you will be using. The fuse
should be the glass cartridge slo-blow type. The rating should be 25 Ampere by 230V AC, 16
Ampere by 400 V AC.
1.4 The Amplifier is constructed with a forced air cooling. Free air movement has to be provided and
considered during positioning.
Do not operate the Amplifier in excessively warm locations or near heating vents or radiators.
Be sure air can circulate freely around and through the Amplifier cabinet, and can provide an
unobstructed air inlet for the internal cooling fan. Do not place any books, magazines, manuals,
or equipment that will impede the free flow of air near the sides and the hot air exhaust holes
located on the top of the cabinet. The internal fan allows an air flow of approximately
200m3/hours. The exhaust air becomes quite warm at high power levels. Do not position any
heat-sensitive objects in the exhaust airflow path.

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1.5 The PA is constructed with the following protection circuits and useful features:
-Heat up time checking circuit (3min)
-Protection circuits (Ia, Ig1, Ig2, temperature, SWR>3, ext.)
-Cooling fan 250m3/h, 230V, 60W.
-Function and status indicator LEDs (6 pcs)
-4.5KVA transformer
-OPTO coupled PTT switch
-Built in I/O coax relays
-External HV power supply (ME2500-S,ME3000-S)

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2.0 S P E C I F I C A T I O N S
ME3000-V
Frequency coverage 144-146MHz
Operating modes ALL mode
Output Power 3000 W pep min. CW/SSB
Driving Power 0-40W max.
Input VSWR max 1:1.5
In/Out impedance 50 Ohm
Valve(s) GU78B
T/R System opto 24V/8mA OPEN COLL. OK
Harmonic supression >50dB at 2500W RF out
Intermodulation >35dB at 2500W RF out
Protection Ia > 1.5A
Ig1 > 20mA
Ig2 > 40mA
Temp > 75Co
VSWR > 2
Dimension 19X14X14 coll
Weight 22kg

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3.0 TECHNICAL DESCRIPTION
1. GENERAL
RF deck of this amplifier is built in aluminium compartment wich must be
electrically tight to avoid RF radiation. RF radiation will decrase output power
and can cause self oscillation of the transmitter chain as well as a health risk.
We can built in normal19” “box” version the line ME3000..
2. INPUT CIRCUIT
Tube is driven in grid 1 with grounded catode. Grid 1 is loaded with 200 ohm RF
power resistor in order to decrease gain end increase stability factor. Loading
resistor is connected on the “way” between grid 1 and resonance tuning
capacitor of the matching circuit due to this parasitic inductance of the tube
plus tube socket. The input circuit is working between 144-146 MHz without
extarnal tuning. The input SWR is better than 1:1.5 in this segment.
3. OUTPUT CIRCUIT
Output resonator is based on W6PO design. Tuning for resonance should be
done by changing length of two resonators rather than increasing C5 tuning
capacitor. The output capacitor value is about 3-4 pF.
Tune is very easy to maximum output .
4. COOLING
Cold air inlet is located in to input conpartment. We can deliver the PA with
internal or external fan.
Air flows trought over the catode box and across the tube body and anode
cooling fins. Hot air outlet is located above the tube anode cooling fins. The
protection circuit will work over 75 degr air temperature.
5. TUNING THE AMPLIFIER
Tuning the input resonance circuit should be done using VSWR meter
connected between driver and input. Output coupling capacitor should be set as
on the schematic to about 4pF.
Output you can indicate across the built in power meter. /FWD knob in/ The
output is 3KW in right end of the meter. /10x scale/ All was made by the factory /
Before any high voltage will applied to the tube, tube should be run on heater for
several hours especially if the tube wasn’t use for long time. From this point of
time, cooling must be operational.
Having heater voltage connected to the tube without adequate cooling will
damage the tube.

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The anode voltage should be applied from your external high voltage supply ME
3000-S and idle conditions of the amplifier checked. Push the PTT and you can
see about 150mA on left meter. When you have more than this value, you can
adjust for this value with P1 poti on UG1 stabilizer PCB. /On case you use home
brew HV supply with lower or larger Ua voltage than 2500Von case ME2500-V
and 3500Von case ME3000-V.

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3/a FRONT PANEL
1. POWER ON
Main switch of the equipment is on the power supply (ME2500/3000-S).
2. ON LED
The LED indicator glows when the Linear is switched on. Doesn’t lit in case the
24V DC –supply for the protection circuits and antenna switch -is missing.
3. OVR LED
The blinking LED indicates the active stage of the protection circuit. The
protection might be active due to overdrive, IG1 higher as specified, SWR > 3,
or any other case. (See specifications)
If the protection is active, the TCVR power by-pass the PA. To reset the
protection release the STBY button, than push it again. The reason of the
trouble has to be cleared first.
4. AIR LED
The indicator glows while transmitting and the T/R relay is switched on. Without
driving power the PLATE meter indicates the base current of 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 by the STBY/OPR
switch on front page. In case the OPR mode is not active, only the TCVR power
is on the aerial. (Small PWR STBY mode)
8. Ua PUSHBUTTON
Selects the anode voltage (kV) indication on the POWER meter using the PLATE
scale. There is only one way selection between Ua -Ig2 pushbuttons.
9. Ig1
The current of the grid (Ig1) can be checked. Current limit is 20 mA, when the
protection is activated.

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10. FWD
Output power indication. Used for tuning the Linear. The indication calibrated
for 50 ohm aerial impedance.
At other values the accuracy may be +-10%.
11. REV
Will indicate the relative reflected power on the right side meter. Helps to check
the aerial.
12. Ig2
The concerning grid current can be checked (max 50mA).
13. STBY
The PA can be driven only if this button is on OPR, otherwise the TCVR power
by-passes the PA. In case the overload protection is active, release the switch
and push it again.
14. PLATE meter
Indicates always the anode current of the PA. The green mark is the limit for the
base current, while the red shows the maximum allowable current.
15. POWER meter
Multifunctional meter. Forward or reflected power, anode voltage or grid
current indications can be selected.
16. TUNE knob
Tuning knob of the anode cavity. Use for tuning the PA.

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3/b REAR PANEL
1. Remote connector
Connecting with short cable to ME2500-S or to ME3000-S power supply.
2. FAN 1
Cooling fan for the RF tube (230V/AC)
3. PTT
Connection for PTT RCA. The relays are closed by earth connection. Low
voltage, low current opto entry. Fit for open collector control a well (24V 10mA).
5. INP
Input connection for the driver TCVR. 50 Ohm.
6. OUT
Aerial connection 50 Ohm (“ 7/16”connector).
7. GND
Ground connection.
8. 5PIN tuchel connector
Connect to external units, preamplifier, etc….

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4.0 INSTALLATION
4.1 Connect your TCVR to the Linear using a short, 50 Ohm coaxial cable.
4.2 Connect your TCVR ground giving connector to the PTT RCA connector on the
rear panel of the Linear, using a screened cable.
In case your TCVR has an open collector PA controller output, you can use it
without difficulties. The input of the PA PTT is 24V 10mA.
4.3 Connect your aerial to the OUT socket of the Linear. VSWR must be better than
1:2.
4.4 Using a flexible cable at least 6mm2, connect your PA to a suitable grounding
point and to the grounding point of the transceiver, and to ME3000-S HV power
supply.
4.5 Connect the power cord to the mains and switch on the equipment (ME3000-S).
Check before the exact input voltage of the ME3000-S (230 or 400V AC!). The
ON LED glows and the WAIT led start blinking for a period of abt. 180 sec,
during the heating period.
The readiness of the Linear is indicated by the OPR LED. If the PA was out of
use for a longer period (2-3 month), it would be advisable to keep the PA heated
without driving for a few hours. The control unit switch the high voltage to
linear, when the OPR LED lits. The vacuum relay can switch the HV only on
case if you connected the HV cable to linear!
4.6 Using the tuning mode of the TCVR (CW) give driving power to reach 300-400
mA indication on the PLATE meter. Push the FWD button and with the Tune
knob tune the Linear to reach maximum output power indication. Increase the
driving power until maximum anode current, than carry out fine tuning using
the Tune knob again. In case a 50 Ohm aerial, the power meter will indicate the
output power exactly.
REMEMBER THIS AMPLIFIER DOES NOT REQUIRE MUCH DRIVE POWER. SO
START WITH LOW DRIVE POWER, AND THEN TUNE TO RESONANCE AS
OUTLINED ABOVE. OTHERWISE, ARCING MAY OCCUR INSIDE YOUR
AMPLIFIER.
NEVER RUN YOUR AMPLIFIER FOR ANY SUSTAINED PERIOD WITH A SCREEN
CURRENT READING GREATER THAN SPECIFIED. IF YOU DO, POSSIBLE
DAMAGE AND FAILURE OF THE TUBE(S) WILL RESULT, AND THEY WILL NOT
BE COVERED BY WARRANTY!
4.7 Check the grid 1 current using the Ig1 push-button. Reduce the driving power or
make fine tuning in case the grid current would exceed THE SPECIFIED VALUE!
Check the G2 current with G2 pushbutton.

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4.8 During SSB transmission the peak power of the TCVR may exceed the allowed
maximum driving power of the transceiver! Use The POWER knob on the TCVR
in this case.
4.9You can not switch the Amplifier to transmission if Ua, UG2, or UG1 voltage is
missing (You can control these voltages on LEDs of control unit.)
4.10 You can use for external units the TX-GND and RX-GND contacts of G2
stabilizer PCB. The delay is 100mSec from RY1 input relay.

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5.0 TROUBLESHOOTING
Malfunctions are mostly due to improper handling, overload or similar reason.
5.1Do not use higher input power as stated in the specification. The grid protector
circuit will usually safe the power valves, but OVERLOAD alarm will appear
regularly. This may happening often in SSB mode, especially in case of old
transceivers, when the output power in SSB mode is not adjustable. The ‘MIC
GAIN’ knob is not fit for power reduction!
5.2 INPUT SWR
The input SWR of the Linear is < 1:1,2.
A well adjusted TCVR will tolerate these values without any trouble.
5.3 OUTPUT SWR
The protection of the Linear will block the transmission in case the SWR of the
aerial exceed 1:2.
5.4 FAILURES
¾The PA not turn on, nothing happens ON switch is pushed.
External AC wiring, fuse or circuit breaker may be open.
Amplifier power cable not in place -cover safety interlock open.
Fuse F1, F2,F3, F4 open or missing -check fuses with an ohmmeter.
¾The PA turns on but no HV is indicated on meter.
Possible HV circuit fault.
HV sampling resistor in power supply damaged.
The HV cable is not on his connector.
The OPR LED not lits.
¾No base current when you push the PTT (about 150 mA on meter).
Not Ua, Ug2 or Ug1 voltage.
Check fuses on Ug2 and Ug1 board, check both stabilizer board.
(Bottom side of PA)
¾The base current is too low or too high.
Check the Ig1 and Ig2 voltage on his PCB boards. (-Ug1 approx. -65V,
Ug2 must be 295V) You can set the base current on minor PCB of Ug1
stabilizer panel.
¾You can indicate Ip current on meter when drive PA but no output power.
Check the output coaxial relay.

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5.5 LIMITED WARRANTY
The M+E Mechanics & Electronics will warrant that the equipment will perform
substantially in accordance with the written materials for a period of 12 month
from the date of receipt and will be free from defects in material and
workmanship under normal use. This Limited Warranty is void if failure of the
equipment has resulted from accident or misapplication, any kind of
modification done, overvoltage, shipping, and in case the damage of the power
valves.
Warranty repairs done only on the base of the M+E Mechanics & Electronics.
Return cost will be covered by the owner.
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 pr otective
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 ava ilable 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 thi s 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 cop per 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.

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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.