Acom International Inc A1010 User Manual
Exhibit 6 page 13 of 15
5-2. Fuse Replacement
CAUTION
For 120 V ac operation, the fuses should be rated at 10 A; for 240 V ac operation, the fuses should be rated
at 6.3 A. If it is necessary to replace the line (mains) fuses, use only those that are permitted under local
safety codes.
The two primary line (mains) fuses in the amplifier are located on the rear panel (Fig. 2-1). They are of the
fast (quick blow) type, European size 5 x 20 mm. Use 10 A for 100-120 V ac operation; 6.3 A for 200-240 V
ac operation. Suitable types are:
For 120 V: 10 A 250 V 5 x 20 mm fast (quick blow), Littlefuse 0217010; Wickmann 1942100000
For 240 V: 6.3 A 250 V 5 x 20 mm fast (quick blow), Littlefuse 021706.3; Wickmann 1931630000
Besides the primary fuses, there are also fuses located on the HV PCB and on the MAINS PCB (inside the
amplifier). They are European size 5 x 20 mm, 2 A and 5 A, time lag (slow-blow) type.
Suitable types are:
HV PCB: 2 A 250 V SLOW BLOW (Time Lag) 5 x 20 mm; Littlefuse 0218002; Wickmann 1951200000
MAINS PCB: 5 A 250 V SLOW BLOW (Time Lag) 5 x 20 mm; Littlefuse 0218005; Wickmann 951500000
These latter fuses must not be replaced by the user. Replacing these internal fuses is potentially dangerous
and must be done only by a trained service technician. Contact your Acom dealer for assistance.
at 6.3 A. If it is necessary to replace the line (mains) fuses, use only those that are permitted under local
safety codes.
The two primary line (mains) fuses in the amplifier are located on the rear panel (Fig. 2-1). They are of the
fast (quick blow) type, European size 5 x 20 mm. Use 10 A for 100-120 V ac operation; 6.3 A for 200-240 V
ac operation. Suitable types are:
For 120 V: 10 A 250 V 5 x 20 mm fast (quick blow), Littlefuse 0217010; Wickmann 1942100000
For 240 V: 6.3 A 250 V 5 x 20 mm fast (quick blow), Littlefuse 021706.3; Wickmann 1931630000
Besides the primary fuses, there are also fuses located on the HV PCB and on the MAINS PCB (inside the
amplifier). They are European size 5 x 20 mm, 2 A and 5 A, time lag (slow-blow) type.
Suitable types are:
HV PCB: 2 A 250 V SLOW BLOW (Time Lag) 5 x 20 mm; Littlefuse 0218002; Wickmann 1951200000
MAINS PCB: 5 A 250 V SLOW BLOW (Time Lag) 5 x 20 mm; Littlefuse 0218005; Wickmann 951500000
These latter fuses must not be replaced by the user. Replacing these internal fuses is potentially dangerous
and must be done only by a trained service technician. Contact your Acom dealer for assistance.
5-3. Tube Replacement
A single Svetlana 4CX800A (GU74B) high-performance ceramic-metal tetrode is used in the amplifier.
Replacement is a complex and potentially dangerous operation that involves adjustment of the plate idling
current. This should not be attempted by the user. Contact your Acom dealer.
Replacement is a complex and potentially dangerous operation that involves adjustment of the plate idling
current. This should not be attempted by the user. Contact your Acom dealer.
5-4. Simplified Schematic Diagram
See Fig. 5-1 ACOM1010 Simplified* Schematic Diagram. The 4CX800A (GU74B) Svetlana high
performance ceramic-metal tetrode (V1) with plate dissipation of 800 W is grid-driven. The input signal from
the RF INPUT jack is passed through a broadband input matching circuit, which consists of components on
the INPUT PCB and includes the drive-power swamping resistor Rsw. This circuit tunes out the input
capacitance of the tube. The swamping resistor Rsw is a termination load for the matching circuit and can
dissipate up to 80 W of RF drive power. It also eliminates any tendency toward oscillation by the tube,
ensuring excellent RF stability of the amplifier.
The cathode resistor Rc creates DC and RF negative feedback, thus stabilizing gain and equalizing
frequency response. The combination Lp1-Rp1 in the plate circuit is a VHF/UHF parasitic suppressor. DC
plate voltage is fed through chokes RFC1-RFC2 and the capacitor Cb3 blocks it from the output. The output
tank, comprised of LP1, LP2, LL, CP1, CP2, and CL1-CL3 , form a classic Pi-L network and suppress
harmonic frequency emissions. This circuit is switched and tuned by S1A-S1C and the air variable
capacitors CP1, 2 and CL1, 2. The output signal is fed through the antenna relays K1 or K2 in the
WATTMETER PCB. The WATTMETER PCB also includes a high-pass filter for frequencies below 100 kHz,
and it prevents the plate supply from reaching the antenna.
The plate RF voltage is monitored through the capacitor Ca and together with the RF WATTMETER is the
main source of information for the control circuit of the amplifier in evaluating tuning quality. The control
circuit is based on the ATMEGA-8L micro-controller from Atmel. All voltages are delivered from the line
(mains) and HV PCBs. The currents of the control grid, screen grid, and the plate, as well as the reflected
power and tuning quality, etc., are continuously monitored by the micro-controller. Many software-derived
protections are based on this information.
* Detailed electrical schematic diagrams are available from ACOM or from your dealer on request.
performance ceramic-metal tetrode (V1) with plate dissipation of 800 W is grid-driven. The input signal from
the RF INPUT jack is passed through a broadband input matching circuit, which consists of components on
the INPUT PCB and includes the drive-power swamping resistor Rsw. This circuit tunes out the input
capacitance of the tube. The swamping resistor Rsw is a termination load for the matching circuit and can
dissipate up to 80 W of RF drive power. It also eliminates any tendency toward oscillation by the tube,
ensuring excellent RF stability of the amplifier.
The cathode resistor Rc creates DC and RF negative feedback, thus stabilizing gain and equalizing
frequency response. The combination Lp1-Rp1 in the plate circuit is a VHF/UHF parasitic suppressor. DC
plate voltage is fed through chokes RFC1-RFC2 and the capacitor Cb3 blocks it from the output. The output
tank, comprised of LP1, LP2, LL, CP1, CP2, and CL1-CL3 , form a classic Pi-L network and suppress
harmonic frequency emissions. This circuit is switched and tuned by S1A-S1C and the air variable
capacitors CP1, 2 and CL1, 2. The output signal is fed through the antenna relays K1 or K2 in the
WATTMETER PCB. The WATTMETER PCB also includes a high-pass filter for frequencies below 100 kHz,
and it prevents the plate supply from reaching the antenna.
The plate RF voltage is monitored through the capacitor Ca and together with the RF WATTMETER is the
main source of information for the control circuit of the amplifier in evaluating tuning quality. The control
circuit is based on the ATMEGA-8L micro-controller from Atmel. All voltages are delivered from the line
(mains) and HV PCBs. The currents of the control grid, screen grid, and the plate, as well as the reflected
power and tuning quality, etc., are continuously monitored by the micro-controller. Many software-derived
protections are based on this information.
* Detailed electrical schematic diagrams are available from ACOM or from your dealer on request.