[TowerTalk] what size wire for kilowatt TX ??

[Roger (K8RI)]

jimlux wrote:
> Martin Ewing wrote:
>   
>> Chas,
>>
>> A little math shows that 5.5 Amps rms into 50 ohms is 1.5 kW.  My handbook
>> says the DC "fusing current" of #26 copper is 20 Amps.  RF skin effects
>> increase the resistance (perhaps by 5X at 10 MHz) and heating (25X).  But
>> you're not going to have 5.5 Amps continuous.  For SSB, the average power is
>> going to be much less than 1.5 kW, so you might squeak by, assuming the SWR
>> isn't too bad.  I wouldn't use insulation.  All in all, #26 wire would be a
>> poor choice for high power -- but hams have been known to try these things.
>> Note that the current is normally greatest at the feed point and decreases
>> toward the ends of a half wave dipole.  So you could taper the wire size
>> down toward the ends.
>>     
>
> Good point (although I don't think the dissipation goes up as the square 
> of resistance)
>   
P=I^2 R

73

Roger (K8RI)
>