TX range expansion on HF, VHF and UHF is very simple. When modified the radio will also transmit AM mode in the aircraft band with approximately 1 watt at 118 MHz to about 17 watts am carrier at 136 MHz.
On MAIN BOARD under speaker near Xtal you can see two rows of solder dots for SMD components. Only on position 10 (from left) is diode (D2030), which is necessary to remove.
Thats all.
After connecting power radio will be reseted and TX range is expanded.
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Transmit power output after modification
Power output in watts as measured from an uncalibrated Diawa CN-620 wattmeter with vhf,uhf dummy load. Power output on radio set to highest level.
| FREQ | FM PWR | AM CARR | FREQ | FM PWR |
| 105 MHz | 1.0 | 0.0 | 400 MHz | 2.0 |
| 110 | 1.0 | 0.0 | 405 | 7.0 |
| 115 | 2.0 | 0.0 | 410 | 9.0 |
| 118 | 3.5 | 0.7 | 415 | 10.0 |
| 120 | 5.0 | 1.0 | 420 | 12.0 |
| 125 | 14.0 | 3.5 | 425 | 15.0 |
| 130 | 20.0 | 15.0 | 430 | 18.0 |
| 135 | 25.0 | 17.0 | 435 | 20.0 |
| 140 | 28.0 | 18.0 | 440 | 20.0 |
| 145 | 32.0 | 18.0 | 445 | 19.0 |
| 150 | 32.0 | 18.0 | 450 | 18.0 |
| 155 | 20.0 | 18.0 | 455 | 15.0 |
| 160 | 13.0 | 10.0 | 460 | 8.0 |
| 165 | 6.0 | 1.5 | 465 | 0.8 |
| 170 | 1.5 | 0.0 | 467 | 0.15 |
| 175 | 0.5 | | 470 | 0.00 |
| 180 | 0.1 | | | |
| 185 | 0.0 | | | |
|
These are the readings I took after performing the mod. I took readings at key frequencies troughout the band to measure the efficiencies of the different band pass filters, especially in the HF band. The attenuation at the edges of the filters are very visible especially at the 8MHz crosspoint.
All readings were took with a bird wattmeter and a home made RF voltmeter, the latter is not reliable over 200MHz.
| MHz |
V @ 50 Ohms |
W from Bird Wattmeter |
W
from RF Voltmeter |
| 0.1 |
0,00 |
- |
0,00 |
| 0.2 |
0,04 |
- |
0,00 |
| 0.3 |
0,31 |
- |
0,00 |
| 0.5 |
1,95 |
- |
0,01 |
| 0.65 |
4,16 |
- |
0,11 |
| 0.75 |
8,60 |
1,5 |
0,59 |
| 0.85 |
24,20 |
7 |
5,25 |
| 0.95 |
52,00 |
18 |
25,01 |
| 1.2 |
98,20 |
75 |
90,37 |
| 1.5 |
99,40 |
80 |
92,61 |
| 1.995 |
104,70 |
87 |
102,82 |
| 2 |
107,90 |
86 |
109,25 |
| 3 |
101,40 |
92 |
96,40 |
| 3.995 |
104,60 |
95 |
102,62 |
| 4 |
95,80 |
92 |
85,98 |
| 6 |
103,40 |
96 |
100,27 |
| 7.995 |
88,60 |
75 |
73,45 |
| 8 |
99,70 |
95 |
93,17 |
| 10 |
103,20 |
98 |
99,88 |
| 14.995 |
101,90 |
96 |
97,36 |
| 15 |
102,40 |
96 |
98,32 |
| 20 |
102,40 |
96 |
98,32 |
| 21.995 |
101,80 |
95 |
97,17 |
| 22 |
102,20 |
96 |
97,94 |
| 25 |
101,20 |
94/92 |
96,02 |
| 28 |
99,50 |
90/90 |
92,80 |
| 29.995 |
97,90 |
86/87 |
89,81 |
| 30 |
95,60 |
82/82 |
85,61 |
| 35 |
93,80 |
80 |
82,40 |
| 38 |
91,30 |
76 |
78,03 |
| 40 |
89,30 |
77 |
74,62 |
| 43 |
95,10 |
85 |
84,71 |
| 48 |
97,30 |
89 |
88,71 |
| 50 |
98,00 |
90 |
90,00 |
| 54 |
100,20 |
93 |
94,12 |
| 56 |
100,90 |
94 |
95,45 |
| 58 |
99,10 |
90 |
92,05 |
| 59.5 |
94,10 |
82 |
82,93 |
| 59.995 |
89,90 |
72 |
75,64 |
| 60 |
13,50 |
1 |
1,56 |
| 62 |
16,50 |
1,25 |
2,37 |
| 65 |
26,40 |
3 |
6,27 |
| 70 |
55,40 |
14/22 |
28,44 |
| 75 |
63,30 |
22/37 |
37,25 |
| 78 |
71,00 |
27/50 |
46,98 |
| 80 |
71,90 |
2752 |
48,19 |
| 83 |
65,50 |
22/40 |
39,91 |
| 86 |
54,40 |
15/28 |
27,41 |
| 90 |
39,20 |
7/14 |
14,09 |
| 95 |
22,00 |
1,5/4 |
4,31 |
| 100 |
14,30 |
0,75/1,8 |
1,76 |
| 105 |
12,10 |
1,3 |
1,23 |
| 110 |
9,80 |
1 |
0,79 |
| 115 |
7,40 |
0,5 |
0,43 |
| 120 |
7,30 |
- |
0,41 |
| 125 |
11,30 |
1 |
1,07 |
| 130 |
22,60 |
5,2 |
4,56 |
| 135 |
47,00 |
21 |
20,37 |
| 140 |
63,20 |
37 |
37,13 |
| 145 |
70,30 |
48 |
46,05 |
| 150 |
72,20 |
52 |
48,59 |
| 155 |
60,00 |
34 |
33,42 |
| 160 |
39,50 |
15,5 |
14,31 |
| 163 |
29,90 |
9 |
8,10 |
| 165 |
22,10 |
5 |
4,35 |
| 167 |
15,50 |
2,5 |
2,08 |
| 169 |
10,60 |
1,2 |
0,93 |
| 171 |
7,40 |
0,5 |
0,43 |
| 174 |
4,40 |
- |
0,13 |
| 178 |
1,91 |
- |
0,01 |
| 183 |
0,33 |
- |
0,00 |
| 190 |
0,16 |
- |
0,00 |
| 195 |
0,35 |
- |
0,00 |
| 199.995 |
0,60 |
- |
0,00 |
| 400 |
6,33 |
0,8 |
0,30 |
| 405 |
14,10 |
3,8 |
1,70 |
| 410 |
18,30 |
6 |
2,94 |
| 415 |
20,70 |
7,5 |
3,80 |
| 420 |
24,10 |
10 |
5,20 |
| 425 |
31,10 |
17 |
8,78 |
| 430 |
30,20 |
16 |
8,27 |
| 435 |
29,20 |
15 |
7,72 |
| 440 |
30,90 |
16 |
8,67 |
| 445 |
30,30 |
16 |
8,32 |
| 450 |
28,00 |
14 |
7,08 |
| 455 |
27,40 |
13 |
6,77 |
| 460 |
20,60 |
8.5 |
3,76 |
| 463 |
14,50 |
4.5 |
1,81 |
| 466 |
7,80 |
1.6 |
0,48 |
| 468 |
4,50 |
0.6 |
0,14 |
| 470 |
2,35 |
- |
0,03 |
| 2-30MHz plug |
|
| 2-30Mhz plug /
25-60MHz plug |
|
| 25-60MHz plug |
|
| 25-60MHz plug /
100-250MHz plug |
|
| 100-250MHz plug |
|
| 200-500MHz plug |
|
| Not reliable |
|
|
