some information about the repair of my ic7700 power ... · amplifire input: two times 0 dbm...
TRANSCRIPT
Pictures - IC7700 PA repair
Zawatzki / DF9VH Page 1 of 19 Date: 2015-07-31
Dipl.- Ing. Frank-Pierre ZawatzkiD F 9 V H
Hauffstrasse 775438 Knittlingen
Germany
Priv.Tel : +49(0)7043/33036Fax # : +49(0)32121259487E-Mail : [email protected]
Some information about the repair of my IC7700 Power Amplifire Module
Pictures - IC7700 PA repair
Zawatzki / DF9VH Page 2 of 19 Date: 2015-07-31
Two of three shunt are blowing (three times 10 mΩ in series connection = 30 mΩ)
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Zawatzki / DF9VH Page 3 of 19 Date: 2015-07-31
Preparation for soldering the MELF resistors (Part 1)
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Zawatzki / DF9VH Page 4 of 19 Date: 2015-07-31
Preparation for soldering the MELF resistors (Part 2)
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Zawatzki / DF9VH Page 5 of 19 Date: 2015-07-31
Preparation for soldering the MELF resistors (Part 3)
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Zawatzki / DF9VH Page 6 of 19 Date: 2015-07-31
Left block is 14 x 220 mΩ + 1 x 300mΩ connect in parallel - and the right block the same –> add together = 29.9 mΩ
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Zawatzki / DF9VH Page 7 of 19 Date: 2015-07-31
Side-face
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Zawatzki / DF9VH Page 8 of 19 Date: 2015-07-31
Preparation for testing the both main field-effect transistors
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Zawatzki / DF9VH Page 9 of 19 Date: 2015-07-31
The left field-effect transistor is blowing
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Zawatzki / DF9VH Page 10 of 19 Date: 2015-07-31
Preparation to replace a new pair of main field-effect transistors
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Zawatzki / DF9VH Page 11 of 19 Date: 2015-07-31
View of the two Motorola MRF150 field-effect transistors from an old Siemens printed circuit board
Pictures - IC7700 PA repair
Zawatzki / DF9VH Page 12 of 19 Date: 2015-07-31
Only one of the MaCom`s is blowing - Old Siemens printed circuit board supplied a matched pair of MRF150 field-effect transistors- The other matched pair of VRF150 from Microsemi go into action when the Motorola´s are died
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Zawatzki / DF9VH Page 13 of 19 Date: 2015-07-31
Preparation for measurement the third order IMD
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Zawatzki / DF9VH Page 14 of 19 Date: 2015-07-31
Measurement of the third order IMD
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Zawatzki / DF9VH Page 15 of 19 Date: 2015-07-31
Amplifire Module Gain: 67 dB
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Zawatzki / DF9VH Page 16 of 19 Date: 2015-07-31
CLRWR
A
Ref 5 dBm Att 30 dB
Center 3.54 MHz Span 20 kHz2 kHz/
*
3DB
RBW 50 Hz
VBW 200 Hz
SWT 9.6 s
1 PK *
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
1 Marker 1 [T1 ]
-0.10 dBm
3.543205128 MHz
2
Delta 2 [T1 ]
-76.41 dB
-9.198717949 kHz
Date: 31.JUL.2015 14:07:28
Amplifire Input: two times 0 dBm carriers – 20 dB step attenuator = -17dBm single tone input
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Zawatzki / DF9VH Page 17 of 19 Date: 2015-07-31
A
Ref 15 dBm Att 40 dB
Center 3.54 MHz Span 20 kHz2 kHz/
* RBW 200 Hz
VBW 500 Hz
SWT 500 ms
3DB
*1 PK
VIEW
-80
-70
-60
-50
-40
-30
-20
-10
0
10 1Marker 1 [T1 ]
6.92 dBm
3.537980769 MHz
2
Delta 2 [T1 ]
-32.88 dB
-4.006410256 kHz
Date: 31.JUL.2015 15:00:07
Amplifire Output: two times 7 dBm carriers + 40 dB directional coupler = 50 dBm single tone output (100 W)
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Zawatzki / DF9VH Page 18 of 19 Date: 2015-07-31
Reinsert a low voltage fuse (20 A)
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Zawatzki / DF9VH Page 19 of 19 Date: 2015-07-31
And add a isolation