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the corner of the hood which puts it about as close as possible to the driver. Here are the
results of my RF field strength measurements using a Haladay HI3004 RF field strength
meter when running a 100W FM signal as measured in the front seat near the driver's
head:
Band Field
strength
10M 8
V/m
12M 20
V/m
15M 15
V/m
17M 15
V/m
20M 12
V/m
40M 16
V/m
Outside the vehicle, the field strength was about 30V/m when measured 2M horizontally
from the antenna.
The FM signal was about twice the strength of a typical SSB signal since it puts out
100W at 100% duty cycle whereas SSB was about half of that. So the readings above are
about 2 times higher than you would expect in normal HF operation.
The maximum exposure limit for a controlled environment is 61.4 V/m at 30-300Mhz
and it rises as the frequency decreases according to the equation 1842/f. For an
uncontrolled exposure, the 30-300Mhz limit is 27.5 V/m and increases according to the
equation 824/f as the frequency decreases where f is frequency in MHz
You can see from the readings that the fields inside the vehicle are well below the
maximum allowable for a controlled environment such as a ham station, and even meet
the more stringent limits for an uncontrolled environment. Combine that with the fact that
the measurements were taken at 100W with 100% duty cycle, and you can see that this
antenna arrangement is considered to be safe by FCC standards.
Transmit problems on 80/160M
Some FT100 owners find that they cannot transmit on any bands below 40M. This is
almost always a result of having menu item 61 set to either ATAS-1 or ATAS-2. Since
the ATAS autotuning antenna only works with bands 40M and above, the FT100 will
refuse to transmit on 80 or 160M if you set it incorrectly. To get around this, you need to
set that menu item to Tuner or 'OFF' if you're not using an ATAS antenna.
S-Meter Anomalies
Several owners have noticed that the S-meter on the FT100 tends to be somewhat stingy,
particularly with FM repeaters. Many radios will give 60+dB readings on local FM
repeaters whereas the FT100 will rarely register more than an S-9. Some responses to the
FT100 mailing list indicated that the FT100 was correctly reporting signal strength
whereas all the rigs that give readings such as 60+dB were overloading and going into
limiting. If you would like to make the S-meter more sensitive, here are the procedures:
•
First off, tune the radio to receive a strong signal from a local 2M FM repeater.
Summary of Contents for FT-100 Micro Mobile
Page 1: ...Yaesu FT 100 undocumented Compiled by PA3GMP Printed 4 April 2004...
Page 10: ...9 ATAS 100 Disassembly...
Page 11: ...10...
Page 12: ...11...
Page 13: ...12...
Page 20: ...19 After the factory mod...
Page 22: ...21 Prior to modification...
Page 23: ...22 Prior to modification...
Page 24: ...23 After modification...
Page 37: ...36...
Page 46: ...45 FT100 menu settings Entry Set to Description Remarks...
Page 47: ...46 FT100 menu settings Entry Set to Description Remarks...
Page 48: ...47 FT100 menu settings Entry Set to Description Remarks...
Page 49: ...48 FT100 menu settings Entry Set to Description Remarks...
Page 50: ...49 FT100 menu settings Entry Set to Description Remarks...
Page 51: ...50 Frequency list Freq Mode Memory Description...
Page 52: ...51 Frequency list Freq Mode Memory Description...
Page 53: ...52 Frequency list Freq Mode Memory Description...
Page 54: ...53 Frequency list Freq Mode Memory Description...
Page 55: ...54 Frequency list Freq Mode Memory Description...