[Elecraft] Excessive SWR Faulting KPA500

Sat Apr 18 20:33:07 EDT 2020

Hi Andy, 

A very close 40 meter antenna is much safer than a close 12 or 10 meter antenna 

See FCC Amateur Radio Regulations: Part 97.13 Restrictions on station location. 

(c) Before causing or allowing an amateur station to transmit from any 
place where the operation of the station could cause human exposure to 
RF electromagnetic field levels in excess of those allowed under §1.1310 
of this chapter, the licensee is required to take certain actions. 

(1) The licensee must perform the routine RF environmental evaluation 
prescribed by §1.1307(b) of this chapter, if the power of the licensee's 
station exceeds the limits given in the following table: 
Evaluation required if power in (watts) exceeds: 
160m 500 watts 
80 m 500 watts 
75 m 500 watts 
40 m 500 watts 
30 m 425 watts 
20 m 225 watts 
17 m 125 watts 
15 m 100 watts 
12 m 75 watts 
10 m 50 watts 

(2) If the routine environmental evaluation indicates that the RF electromagnetic 
fields could exceed the limits contained in §1.1310 of this chapter in accessible 
areas, the licensee must take action to prevent human exposure to such RF 
electromagnetic fields. Further information on evaluating compliance with these 
limits can be found in the FCC's OET Bulletin Number 65, “Evaluating 
Compliance with FCC Guidelines for Human Exposure to Radiofrequency 
Electromagnetic Fields.” 

73 
Frank 
W3LPL 

----- Original Message -----

From: "Andy Durbin" <a.durbin at msn.com> 
To: elecraft at mailman.qth.net 
Sent: Sunday, April 19, 2020 12:07:13 AM 
Subject: [Elecraft] Excessive SWR Faulting KPA500 

"At a distance of only six feet to your antenna, perhaps your amplifier is trying to warn you that you may also have a human RF safety issue. " 

Well, do you feel warm.... 

We do what we must to get a signal out. My 40 m dipole is in the attic of a single story house under an asphalt and fibreglass radome. Yes I have RF in the "shack" and every other room in the house. My choice how high I turn the wick though and that choice is less than 500 W. My "controller" prevents my getting excited and turning the wick up all the way. 

Antenna is well matched though and KPA500 is happy. The only problems I've had with an unhappy KPA500 were on 20 m. 

73, 
Andy, k3wyc 

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