Feedback resistors getting hot

[David Duncan]

Hello,

I've built the 100 W amp and set the bias to 100 mA from a 50 vdc linear power supply.

Feeding it 1 Watt from K2 produces approx 100 W output.  After a minute at 100 W I notice that the 100 ohm feedback resistors (R1, R6, R7 & R8) are too hot to touch.  Is this normal or do I have a problem?

[jcve...@gmail.com]

That sounds about right. The feedback resistor dissipates about ~5W at 100W output, depending on frequency and output match.

the specified resistors are rated at 2W each for a total of 8W. The maximum operating temp is 155C which, if you touched it, would certainly qualify as way more than 'hot to touch'.

More like 'burned the skin off my finger'.

73,

Jim WA2EUJ

[David Duncan]

Thanks for the info. More testing and measurements today.  I haven't lost any skin yet!