[RFI] Re: [TVI-RFI-EMI] RF safety

[k6ll@juno.com]

On Thu, 12 Feb 1998 05:34:34 -0500 Ray LaRue <raylarue@gte.net> writes:
(to the tvi-rfi-emi@qth.net reflector)

>Here is a webpage address which can be used to estimate your RF 
>exposure situation, as per the new FCC rules. 
>http://www.cs.utexas.edu/users/kharker/rfsafety/

Here is a little front-end calculation sheet that I put together
for a little more sophisticated input to that Web page. You will
need a scientific calculator for step H. Just overwrite the sample
data with data pertaining to your own station.

A. Callsign: K6LL

B. Frequency, Mhz: 21.45

C. Maximum PEP transmitter output, watts: 1500

D. Type of feedline: RG-213

E. Length of feedline, ft: 80

F. Feedline loss, negative dB: -.8

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 ALOG (-.08) = 1248
        (typical calculator steps: .08, +/-, 10^x, X, 1500, =)

I. Worst case (highest) Emission Mode Duty Factor: .4
     FSK, RTTY AFSK SSB, FM VOICE: 1.0
     Conversational SSB, heavy speech processing: 0.5
     Conversational SSB, moderate speech processing: 0.4
     Conversational SSB, no speech processing: 0.2
     Conversational CW: 0.4

J. Transmit/Receive Duty Cycle over six minutes: .6
     (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 30 minutes,
     expressed as a decimal.)

L. AVERAGE power to the antenna, controlled case. (H x I x J)
     1248 x .4 x .6 = 300

M. AVERAGE power to the antenna, uncontrolled case. (H x I x K)
     1248 x .4 x .5 = 250

N. Antenna Gain, dBi: 9.5

O. Closest CONTROLLED human proximity to antenna, feet: 46

P. Closest UNCONTROLLED human proximity to antenna, feet: 51

Q. Print the above sheet, with all info filled in. Do it for each band.

Proceed to the University of Texas World Wide Web Site:
http://www.cs.utexas.edu/users/kharker/rfsafety

Input items L, N, O, B (controlled case). Print the output sheet.
Input items M, N, P, B (uncontrolled case). Print the output sheet.

In both cases, select the option at the bottom of the web page
to include the effects of ground reflections.



Dave Hachadorian, K6LL
Yuma, AZ
K6LL@juno.com


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