[OFARC] RF safe distances for FD UTC Calculation

[MLandress]

Goo tip on the RF exposure Ralph.   I've attached an actual RF calculation
for my station where I run verticals.  This is 2 dB antenna gain, 2 dB coax
loss, 0.5 dB insertion loss, power and distance as shown.  This  includes
VHF and UHF for both handhelds and mobiles.  This is calculated from the
website as shown.  Since we don't run power on FT8 or RTTY, exposure is
close to that calculated for SSB.  CW is intermittent continuous duty and
given the spacing is about 50% duty cycle, about the same as PEP.
Interesting note that only a few watts on 2M or 440 mHz close to the face
exceeds max permissible exposure (MPE).  A hand held >5 watts clearly
exceeds MPE.  Good case for using a hand mic.  

 

Following up on the net this week.  In every phone and Windows computer
there is a world clock that you can set for UTC time.  Handy to have.  I've
attached a spreadsheet calculation for field day using various date and time
functions if logging is done in a spreadsheet.  Just got to remember UTC is
+ 5 hours from central time.

 

Mark WB5ANN

 

From: ofarc-bounces at mailman.qth.net [mailto:ofarc-bounces at mailman.qth.net]
On Behalf Of ralph phillips
Sent: Thursday, June 23, 2022 12:35 PM
To: OFARC
Subject: [OFARC] RF safe distances for FD

 

I have used an RF safety calculator on the ARRL web page to verify safe
distances from antennas.

I looked at 40m to 10m at 100watts output.  The greatest distance needed is
10m at 100w and 100% duty cycle ( digital) .. 5.2 feet from the antenna to
the operator.

 

 2m and 70cm at 50w FM (100% duty cycle) requires a minimum of 3 feet from
the operator to the antenna.

 

I had previously said to plan on 50 ft of coax.  Now I see we can use
shorter runs and be ok with safety criteria.

I plan on 20 ft to allow walking room around my station.

 

Ralph

KE5HDF

 

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