[Towertalk] Fw: RF Burns

[Ted Leaf]

Hi Guys,

Since I have not asked permission from the authors, I have omitted their 
last names and callsigns.

Ted K6HI
Kona, HI
<tleaf@hotmail.com>

>Subject: Fw: RF Burns

   Dear Mike
>
>   A very quick email while recovering from an incident in the shack 
>earlier today -- a salutory lesson in shack safety and my first experience 
>of RF burns.
>
>   While following  with extreme care the instructions in the ICOM 4KL 
>amplifier manual for setting the ALC level , I stupidly overlooked the 
>equally important instructions on RF safety for the new, replacement 
>antenna tuner.  I am currently using a long wire antenna which, of 
>necessity, comes right into the shack and is connected to a ceramic lug at 
>the rear of the tuner .  With the 4KL amplifier set at full power, while 
>leaning over the amplifier to adjust the ALC knob at the rear, I touched 
>the ceramic lug connector with my foream.  I'm sure that I felt no pain at 
>the time; but a brief, loud hiss, together with the combined  odours of 
>singed hair and sizzling bacon made me jump back very quickly.  My heart 
>was really pounding and I thought that I must have  sustained a powerful 
>electric shock.  In the event it was an RF burn.  Something I have read 
>about often but never experienced.  The pain and discomfort throughout the 
>day has been such that I will certainly never let vigilence slip like that 
>again.  I will certainly carry a scar to act as a salutory reminder 
>because, although quite small, the RF burn has actually removed the tissue 
>at the point of contact down to quite a depth.

>>While I nurse my forearm, have a good weekend.
>
>   Norman

>
>
>Dear Norman -
>
>Thank you for the interesting and enjoyable e-mail. I'm very glad that 
>you're recovering well from both of your recent adventures! It is a 
>testimony to your strong consitution that the results were only scrapes, 
>bruises, soreness and singed skin.
>Somehow I feel that the blame for your approach to RF and the like, rests 
>with a few of us who unintentionally(?) infected you with our tendancies. 
>Doubtless there was ample opportunity to have this happen early in the 
>formative years of your ham career (during a visit to Atlanta, Ga and 
>allowing several rebellious colonists-types in your home in 1992)!  
>Therefore we share the blame and ought receive some of Mena's venom.
>To confess, I know first-hand that rf energy readilly arcs to points 
>(fingers, elbows, nose, lips, hair, etc.) and burns down to the bone!
>As a 12 or 13 year old, not having the finances to own a wattmeter, I 
>checked the tuning of my transmitter by drawing an arc from the plate cap 
>of the final amplifier tube. The 6146 would produce about 60 watts out with 
>B+ of 700 volts or so applied. A wooden pencil with number 2 lead worked 
>nicely, provided the coating of paint was in tact, ones fingers were dry 
>and the metal cap housing the eraser was not touched. The beautiful blue 
>discharge of some inch  and a half in length indicated maximum rf to the 
>antenna and the best chance to QSO that VK or ZL.
>However, zzzzzzphtttpht on too many occasions signaled I was the 
>uncooperative load. No ham activity followed for several days, as I nursed 
>a charred and sore finger that would shed a section of tissue from the bone 
>out.
>The blister on my left thumb remains unhealed from taking 850 volts to 
>ground from the open hi-voltage cage in a Heathkit SB-102 Transceiver! The 
>circuit was only an inch in length along the thumb, but the parasitic choke 
>lead burned into the nail and flesh for almost that depth. At age 35 it 
>seems that earlier lessons would have been learned?
>Perhaps, you and I have experienced our LAST close calls and the law of 
>averages is now on our side??????

>>Mike
>
>

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