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fatboy failure

It's not what's on the outside but rather what's on the inside that matters. Do you buy a car and not know how many cylinders it has under the hood?

I understand what you are saying. You gotta know what your running and have at least a basic understanding of how it works

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Once you know the gain of the 2879 is more than the 2290, this 3 pill makes as much sense as putting an Ameritron AL80 in front of a Heathkit SB-220. Sooner rather than later you're going to let the smoke out. The 2290 can do about four times the drive a pair of 2879's requires and driving this 3 pill with just about any radio is going to insure it's over driven that hard. Most regular radios can drive a pair of 2879's good and anything more just creates lots of IMD. Sorry to say anyone who builds you a 3 pill is treating you like a jacka$$.
 
Bought a Fatboy 1x2290/2x2879 and have it mated to a Galaxy 739. First day blew some kind of transistor and fatboy fixed for 70 bucks. It lasted another day and blew finals. Pushing it with 5 watts, 1.4 swr, 10 gauge positive and ground. Somebody tell me what is wrong, PLEASE.

Galaxy 739? Is that a typo? I can't find it anywhere.

All things aside, you're overdriving your amplifier. Lower your dead-key to under 2 watts, probably more like 1 watt.
 
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I have a 1x2 FB here I just repaired. Screw holes weren't countersunk. Input is padded pretty good. 2W DK into amp makes I'd DK 40W. Swings like hell. Up to 175w average. That was using a 250w element on the bird. I was using a 148gtl that only does 15W pep max. 5W DK is way too much. That's about what you could put into a 4pill and let it swing safely all day long. Just my 2 cents.
 
The 2879 runs at 13 db and with a 4 watt carrier driving a pair, that's 80 watts carrier that would need to hit 320 watts PEP to modulate 100%. The resistive attenuation in the 1 pill driver stage so that 2 watts in equals 40 out has both the driver and final stage running at a combined gain of only 13 db. The same gain available from just the pair of 2879s without the unreliability over driving offers or the expense of the extra driver stage.
 
Yeah he was probably dking at 300 if his radio was dking at 5. That 2290 probably needs less then a 1 watt key.

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The 1x2 Fatboy I had took less than 1/4 of a watt to get full output from the 2879s, and that was with my variable was turned all the way down. I think I was swinging less than 2 watts into it, and getting wild watts out of it.

5 watts would smoke it short order...
 

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