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Hot News
Hot news is posted
on our home page. These are items of current interest.
Sometimes amplification is
appropriate, and will be posted here.
How to connect your PC. From
ARRL, 28 April, 2021. Bob, N6TV, has updated his presentation "Everything
You Need To Know About USB and Serial Interfaces" for 2021. His
presentation includes the history and evolution of serial ports, chipsets to
prefer and those to avoid, how to use software tools to troubleshoot issues
you might encounter, and how to best utilize the built-in USB to serial
functionality that has been built into some modern rigs to support CAT, CW
keying, and RTTY keying. This is a must read for anyone wishing to connect
their radio and legacy equipment to a PC and logging software,
particularly a PC without serial ports.
How to work a
DX station as quickly as possible using FT8.
Bernie McClenny, W3UR, has offered a suggestion for calling DX while
using FT8.
He advises that FT8 users avoid the "Generated Std Msgs (TX 1)" field
when attempting to call DX on FT8. "You can turn it off by double
clicking on it," he said. "When the band opens up, serious DXers want to
get in and get out as quickly as possible. We don't know how long the
opening will last, [and] the DX station does not care about your grid
locator. You want to get your call sign and report to the DX station as
quickly as possible, so you don't miss the opening. When you are calling
a DX station, set the FT8 software to go to message 2 (e.g., TZ4AM
KZ3ZZZ -14). Then you want to get the "RR73." That is all you need for a
valid contact. During contests where the grid locator is needed, by all
means, send it." ARRL Letter, 7/29/21.
RF Exposure Calculator.
The following is not "live" but shown to describe the
process. The live calculator is found by clicking the following
link.
http://hintlink.com/power_density.htm
RF Exposure Calculator
v2.2 (2021-05-07)
by Paul Evans, VP9KF ,
Hintlink Technology.
Help page.<-- to see CHANGES, go here
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This is
a main beam power density estimation program intended
for use as part of a evaluation of RF safety compliance
with FCC regulations. Amateur Radio operators licensed
by the Federal
Communications Commission of the United States of
America are required to do an evaluation of the strength
of the RF fields around their stations, with the only
exemption being ERP of less than or equal to 0 dBm
(1mW). These rules can be found in the FCC's ET Docket
No. 19-126A1. More information can be found at the ARRL
Website RF
Exposure page.
This program uses the formulae given in FCC OET
Bulletin No. 65 to estimate power density in the
main lobe of an antenna, with use of the EPA-recommended
ground reflection factor as an option. This program is
intended for approximate far-field calculations. It may
overestimate the actual field strength of high-gain
antennas in the near field (within several wavelengths
of the antenna). However, it may also underestimate the
strength of fields that may be encountered in hot
spots in the near field. No computer program can
accurately predict where wiring or reflective objects
may create hot spots in your particular installation.
This is a World Wide Web front
end for a public
domain program written by W4/VP9KF using
PHP.
Terms: GNU
Licence.
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No Warranties: This information is
provided "as is" without any warranty, condition or
representation of any kind, either express or implied, including
but not limited to, any warranty respecting non-infringement,
and the implied warranties of conditions of merchantability and
fitness for a particular purpose. In no event shall we be liable
for any direct, indirect, special, incidental, consequential or
other damages howsoever caused whether arising in contract,
tort, or otherwise, arising out of or in connection with the use
or performance of the information contained on this web site. |
Exemptions
to Routine RF Exposure Evaluations
On 2019-11-27, in a Report
and Order of 159 pages, the FCC adopted no
categorical exemption to routine RF exposure
compliance testing at all Amateur Radio operating
frequencies. Moreover, all stations,
regardless of power level (except 0 dBm and less), must
comply with the RF exposure limits. |
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Average Power Estimate
When amateurs are required to perform
a routine evaluation of the RF exposure around their
stations, the FCC regulations on permissible RF exposure
are not based on peak envelope power (PEP), but on
average power over a 30 minute time period for
uncontrolled environments or a 6 minute time period for
controlled environments.
| Operating Mode |
Duty Factor |
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Conversational SSB, no processing
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20%
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Conversational SSB, with processing
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40%
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| [Voice] FM
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100%
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| FSK or RTTY
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100%
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| AFSK [SSB]
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100%
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| FT4/FT8
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50%
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Conversational CW |
40%
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| Carrier
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100%
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To estimate your average power, first
start with your Peak Envelope Power (PEP). Multiply that
by the duty factor for the mode you are
using, then by the maximum percentage of time you expect
to operate within the averaging period.
For example, if you operate a 1500
watt PEP SSB (phone) station that is on for 10 minutes,
off for 10 minutes and on again for 10 minutes, you are
operating with 200 watts average power (1500 watts PEP *
20% * 67% = 200 watts average power) over a 30 minute
period. If you operate a 1500 watt Morse Code (CW)
station over the same time period, you have 1500 watts *
40% * 67% or 400 watts average power.
In most cases for the 6 minute
controlled environment exposure estimate, you should
probably assume that it is possible to operate over the
entire 6 minute period, so the 1500 watt PEP SSB phone
station would be 300 watts average power for
controlled-exposure calculations. An RTTY, digital
station, beacon station or FM repeater transmitter could
possibly be on for the full 30 minute time period. The
RTTY station or FM repeater would have 1500 watts
average power. If it operated 10 minutes on, 10 minutes
off and 10 minutes on, it would have 1000 watts average
power over 30 minutes.
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