[Boatanchors] Power handling of Viking Kilowatt tuner

[Brian]

Hello John,

Though I don't have a Viking Kilowatt antenna coupling unit (ACU), I do have a Viking Matchbox; so, I know the principles of the Johnson design.

I have also designed and built ACUs. Here are the main concerns:
  a.. The spacing between the Load capacitor plates will limit the maximum Voltage that can be sustained before flashover. That will be determined by the impedance of the antenna system and the power applied, whether AMDSB or SSB. [V = sq rt P.R] For instance, if the antenna is 600 Ohm and the power is 1.5 kW, then the Voltage across the Load capacitor will be ~950 V RMS. If the antenna is an end-fed Zeppelin, with an input impedance of say 5000 Ohm, that Voltage will be 2740 V RMS or 3875 V peak. 
  b.. If the antenna is very low impedance, such as a multi-element beam, then the current carrying capacity of the wire is important.  For instance, if the antenna system impedance is 12 Ohm and the input power is 1.5 kW, the current flowing will be 11.1 A RMS. [I = sq rt P/R] You can do the sums for your FW loop. 
  c.. At high frequencies, the current is carried by the skin of the conductors. At 28 MHz, for instance, the current carrying capacity may be as low as 10% of the usual DC current carrying capacity.

So, if someone tells me X is a 1 kW ACU, I ask, "At what frequency and power?"

I hope that helps, though it means that the answer requires you to open the box and measure the components.

73 de Brian, VK2GCE

On Friday, October 10, 2014 11:48 AM , you said:

Has anyone used the Viking Kilowatt tuner to handle maximum legal limit PLUS of transmitting RF in the AM mode. I understand that the smaller Viking tuner will handle the 2,000 watt PEP legal limit n SSB. Would like to know what the large Viking will handle on AM tuning a full wave loop on 80 meters and on 160 providing the large Viking has been modified for 160 using the Viking recommended modification. Please respond directly because I don't want to instigate a competitive "I know better than you" discussion.

Thank you for sharing your knowledge. 73, John, K5PGW