You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
The Feb 2025 Radioddity Giveaway Results are In! Click Here to see who won!

Reply to thread

Message

A Cobra 2000? With the internal power supply?

Makes it sound as if the power supply regulator has run away, putting more than 13.5 Volts on the radio. The hottest Cobra 2000 on the planet should never show more than about 20 Watts PEP on AM or SSB.

Setting bias current on the final is absolutely the next step, before you toast the final. If the final-bias trimpot is set too high, the final transistor overheats on sideband and power falls off until it cools down.

Or until the radio cooks the final. Have a look at the color of the exposed metal surface on the mounting tab of the final transistor. If it's fuzzy and dark gray or black, it's been running really hot.

73

[QUOTE="nomadradio, post: 797416, member: 22"] A Cobra 2000? With the internal power supply? Makes it sound as if the power supply regulator has run away, putting more than 13.5 Volts on the radio. The hottest Cobra 2000 on the planet should never show more than about 20 Watts PEP on AM or SSB. Setting bias current on the final is absolutely the next step, before you toast the final. If the final-bias trimpot is set too high, the final transistor overheats on sideband and power falls off until it cools down. Or until the radio cooks the final. Have a look at the color of the exposed metal surface on the mounting tab of the final transistor. If it's fuzzy and dark gray or black, it's been running really hot. 73 [/QUOTE]

Top Bottom