Here is an updated version of my RF Safety Worksheet. There were
no errors in Rev. B (as far as I know), just some enhancements in
this version. I hope you find it useful. Let me know if you find any
mistakes.
Dave Hachadorian, K6LL
K6LL@juno.com
Yuma, AZ
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SAMPLE RF SAFETY WORKSHEET (Not Officially Sanctioned) Revision C.
(Not for repeater or multitransmitter use) K6LL, author.
(K6LL@juno.com)
A. Callsign: AA7AAA
B. Frequency, MHz: 21.45
C. Maximum PEP transmitter output, watts: 1500
D. Type of feedline: RG-213
E. Length of feedline, feet: 80
F. Feedline loss, negative dB: -.8
Look this up in a book, or use the program TL
G. Line F divided by 10. (It will be a negative number). -.08
H. PEP power delivered to the antenna: line C antilog line G
1500 antilog (-.08) = 1248 watts
Scientific calculator keystrokes:
.08, +/-, inverse, log, times, 1500, equals
Note - Evaluation is not required if line H does not exceed:
160/80/40m, 500w; 20m, 225w; 17m, 125w; 15m, 100w; 12m, 75w;
10/6/2/1.25m, 50w; 70cm, 70w; 33cm, 150w; 23cm, 200w; 13cm and
shorter, 250 watts.
I. Worst case (highest) Emission mode duty factor: .4(cw/proc.
SSB)
FSK, RTTY, AFSK SSB, FM Voice: 1.0
Conversational SSB, heavy speech processing: 0.5
Conversational CW: 0.4
Conversational SSB, no speech processing: 0.2
J. Transmit/Receive duty cycle over six minutes: .5
Longest conceivable percent transmit time in six minutes,
expressed as a decimal.
K. Transmit/Receive duty cycle over 30 minutes: .5
Longest conceivable percent transmit time in thirty
minutes,
expressed as a decimal.
L. AVERAGE power to antenna, controlled case: H x I x J = 250
M. AVERAGE power to antenna, uncontrolled case: H x I x K = 250
N. Antenna Gain, dBi: 9.5 (large tribander)
Sample gains from OET Bulletin 65, supp B:
3 el triband yagi 20m/6.5 dBi, 15m/7 dBi, 10m/8 dBi
quarter wave vertical 1 dBi
half wave dipole 2 dBi
1/4 wave vhf/uhf whip or GP 1 dBi
5/8 wave vhf/uhf whip or GP 4 dBi
17 el yagi on 5 wavelength boom 16.8 dBi
Discone 2 dBi
O. Closest CONTROLLED human proximity to antenna, feet: 46
P. Closest UNCONTROLLED human proximity to antenna, feet: 51
Print this worksheet, and Proceed to the University of Texas
World
Wide Web Site: http://www.cs.utexas.edu/users/kharker/rfsafety
Select "Include Ground Reflections."
Input items L, N, O, B (controlled case). Print the output sheet.
Input items M, N, P, B (uncontrolled case). Print the output
sheet.
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