[AMPS] Delrin Spreaders, a test

Rich Measures measures@vc.net
Mon, 23 Jun 97 06:24:49 -0700

>AG6K wrote:
>> My first experience with the significance of dissipation-factor was when 
>> I used a General Radio Co.  NYLON double-banana plug at the end of a home 
>> made open wire feedline.  The nylon melted and began foaming.  I changed 
>> the plug to one made from phenolic.  

The amplifier being used at the time was an SB-220.  
>> My second experience was with PVC pipe near the end of a 40m dipole.  As 
>> I was tuning up a home brew AB1/tetrode amplifier, the telephone rang.  
>> My neighbor said: "Rich: your antenna is on fire."   My gut feeling was 
>> that the presence of flames and smoke indicated that it was quite 
>> possibly on fire. 
>> - [note:  the amplifier was delivering about 1150v peak to the RG9 
>> feedline at the time]
>> -Rich-
>That's about 8 kW if the line is matched, but of course none of that 
>gives us any idea what voltage the delrin or nylon failed at.
1150v peak into 50 ohms is not 8kW according to ohm's-law, Mr. Rauch.  

>Someone suggested a microwave, but again we would have no idea how 
>the material would behave at HF  ...snip...

Dissipation-factor in dielectrics increases as frequency increases.  I 
know of no mateial where the opposite is true.  If a plastic does not get 
hot at 2400MHz, it is probably going to be ok at 30MHz.  
- Rich -

R. L. Measures, 805-386-3734, AG6K   

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