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Black Cat AMP


4 pill mosfet

I have a similar amp with 4 of them 75W mosfets in it.
it won't do 500w. Gets close; starts off at about 440 pep and backs off to just over 330 or so once it heats up. It gets hot. Real hot. I put a 220v fan on top to help the internal fan but it seems that the heat just can't get out fast enough. maybe the devices too close together, maybe needs better thermal design using copper or something. It works and its cheap but it doesn't hold a candle to a texas star dx500 that can warble along all day long at 500w.
It seems clean enough and pretty good on sideband but people notice the difference when the texas star takes over. At US$225 I think it is too expensive.
needs to be around the US$175 level. How can these devices be said to be more eficient when they throw out so much heat.? We must be driving them too hard?
maybe 8 transistors and 500w it would have some breathing space?
Bottom line, it is cheap and easy power!
 
Real RF MOSFETs are actually more expensive than normal bipolar RF transistors. What we have here with the CB MOSFETs are actually transistors that were originally classified as power supply switching transistors that operated well below 27 MHz. Some are now even speced to be used as linear amps but as long as they keep them in TO-220 or TO-3P cases, they will never operate efficiently at these frequencies and power levels.
 
dd18 said:
I have a similar amp with 4 of them 75W mosfets in it.
it won't do 500w. Gets close; starts off at about 440 pep and backs off to just over 330 or so once it heats up. It gets hot. Real hot. I put a 220v fan on top to help the internal fan but it seems that the heat just can't get out fast enough. maybe the devices too close together, maybe needs better thermal design using copper or something. It works and its cheap but it doesn't hold a candle to a texas star dx500 that can warble along all day long at 500w.
It seems clean enough and pretty good on sideband but people notice the difference when the texas star takes over. At US$225 I think it is too expensive.
needs to be around the US$175 level. How can these devices be said to be more eficient when they throw out so much heat.? We must be driving them too hard?
maybe 8 transistors and 500w it would have some breathing space?
Bottom line, it is cheap and easy power!
Click to expand...

Do you have any indication of the current draw versus output watts?
 
I was also looking at those 500 models and liked the fact they will take 100 watts drive but have a few Texas Star DX500 and am a diehard fan and also wonder about the output and reliability of the Back Cat 500 as compared to the prover reliabilty and performance of tm Texas Stars.
 
If it's any indication of the quality of the inside of the amp...the front panel is labeled with one of those Dymo label makers. Maybe someone at H&Y is making them.
 

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