Higher than spec transmit Power

[kf7ipx]

I just installed a 2m new homemade 5/8 wave colinear j pole antenna. Slight adjustments got me to a 1.1 swr at 146 Mhz. I am also reading power wattages at 2x what they are supposed to be to the point that I am poping off the overloads on my power supply (15 amps) at the high setting (spec - 75 watts, measuring 150+ on the meter). Does this make sense and if it does, any suggestions? thanks in advance for your time and help.
KF7IPX.

[WA9WVX]

Hello Jim,

You haven't mentioned what type of RF coaxial feedline that you're using, i.e. RG-58A/U, RG-8/U, RG-213/U, RG-8/X, RG-8214, LMR-400, LMR-9913 or LDF4-50A ½” Heliax?

What type of RF connectors are on the feedline PL-259A or N Type Crimped or Soldered?

What the exact Length of the coaxial feedline, measured in Feet & Inches End-to-End?

What is the exact Length & RG Type of your coaxial jumper cable between the transceiver RF Output connector and the RF Input connector on your Wattmeter / VSWR Bridge?

What Brand & Model number of Wattmeter / VSWR bridge are you using?.

Have you tried using a known good VHF 50-OHM Resistive 100 Watt Dummy Load after the Wattmeter / VSWR Bridge?

Then at the end of the 50-OHM RF Cable in place of the Homebrew 5/8 Wavelength “J-Pole” Antenna?

What were the VSWR / Power Output readings in both tests?

Typically the "J-Pole" antennas are a 75-OHM Impedance producing a 1.5:1 VSWR 5% Mismatch unless designed for a 50-OHM Impedance.

If the feedline is an unusual electrical length, then this could cause problems, and if the shield is not crimped or soldered correctly at both ends this could and will produce high VSWR / Power Output readings and unwanted stray RF in the ham shack which might be affecting your Power Supply Overload Circuitry.

Dan
WA9WVX