Magnum S-9 runs very hot in AM/FM

[13EL121]

hi @ all!
I'm using a Magnum S-9 Radio. The "problem" is, that it runs very warm by using FM or AM mode. The output is normal power of 20 watts. It's the latest variable version of the radio with fixed 20 watts in AM/FM at maximum power (dual finals 2230 MOSFET). In SSB mode there is no problem by maximum 45 watts. I'm worried to blow the finals What could it be? Does anyone have this problem too?
Sorry for my bad english...
73s from germany!
Ralf

[James Unit 198]

I destroyed 4 sets of drivers and finals before i got it sorted out by Rick.
I think he still gets on this forum from time to time.

James.

[13EL121]

Hi! Is there a difference in quality of the pills? when i go out with 10 watts only it is much better! But the 2230 should make more power i think... is the heatsink to small for the radio? The other version makes 45 watts on FM says the flyer of magnum.

[frogman296]

fm will make the radio run hotter anyways, as it operates at a higher duty cycle

[windowlicker]

I'm on looking for the same answer as you. Mine also gets very hot, close to to hot to touch. I read the post about the glued on transistor and cannot find it.

[13EL121]

I think it is better to mount an small CPU fan at the back of the heatsink .
Then the "Magnum" sounds even better
In normal CB use i regular the power output down to 10 watts. Then it is ok with the temperature.
73's, Ralf

[frogman296]

I think it is better to mount an small CPU fan at the back of the heatsink .
Then the "Magnum" sounds even better
In normal CB use i regular the power output down to 10 watts. Then it is ok with the temperature.
73's, Ralf

ralf is right..lower the power and let the radio swing freely...a fan would not harm it either...

[Rick]

Try changing C166 this is known to cause the PA strip to run hot, and keep the PA power down to 15 to 18 watts max on FM and 10 watts max on AM.