The Phase Linear 400 Guinea Pig

[laatsch55]

The 400 that got the copper heat sinks on one side was a non-worker on the right channel. Q4 (MPSA-93) was toast, it now is behaving and it is the best example I've gotten of a stocker yet so the AP is gonna have it's way with it to generate some more baseline data.

 

[laatsch55]

Freq response(sucks) 150 mv input , 8 ohm load, DC offset-8mv left, 6mv right. Bias 385 left and right.

 

[laatsch55]

THD & N left channel

 

[laatsch55]

THD & N right channel

 

[Gepetto]

Something wrong on the right channel...

 

[laatsch55]

ya know, it didn't look right to me either. C6 was way out of spec.

 

[laatsch55]

The others..............

 

[laatsch55]

Just a rough measurement till I can refine the process. Took the same analog thermometers I used last night, applied them with modeling clay, one against the wall, the other on the edge.
Fed the amp on the copper channel, 100watts at 1Khz, at 8 ohms.

I guess it doesn't mean much without a time element.

 

[laatsch55]

After approx 5 minutes it stabilized at 150 and 122

 

[laatsch55]

I'll load it up again, this time with some TIME involved.

 

[laatsch55]

The line on the far left is the copper HS table for the thermometer against the wall, next to that is the aluminum in the same position. The 3rd row is the copper thermometer at the end of the heatsink, and the 4thg is the aluminum, same place.

What I didn't have is an infrared thermo to check the TO-3 cases. We'll need that to know how effectively the sink is pulling heat away from the tranny case.. Something to chew on till then.

Temp in degrees farenheit.

 

[Gibsonian]

Lee,

Are your thermometers touching the heat sink directly or is there a layer of clay in between heat sink and thermometer?

 

[laatsch55]

Yes Scott they are touching, must be an optical delusion or took the pic before i had the outside one snugged up.

 

[Gibsonian]

Would definitely not be my first delusion nor likely my last!

 

[laatsch55]

Well, some are rather fun if I remember correctly!!

 

[Gibsonian]

Yes, many were fun, and the ones I cannot remember likely were too.

So are you gonna post temps stock fins vs copper?

 

[laatsch55]

I did Scott. The first line is the copper fin temp. The 2nd is the aluminum temp, the 3rd is the outside copper temp, and the 4th the aluminum outside temp.
Buying an infrared thermo today so we can track the TO-3 case temp relative to the HS temps. Then we'll know.

 

[Gibsonian]

ok, got it. TO3 will tell the tale.

 

[laatsch55]

Eating dinner and warming up the AP now.

 

[laatsch55]

left channel, bias 386Mv, DC offset-6 MV, 100 watt output, 8 ohm load, 782 mv input.

Aluminum heatsink