John Curl amp

[dimitri]

C9 680pf

probably that is why you need that high C10 and C11 (130 pf)
I made a mistake ordering two boards, I should order more and help you to tame it. Nevertheless, you can send me working board and I'll measure it with AP/check stability, etc

 

[MikeW]

That is just what I happen to have. I don't think there are any problems with the board so we can order some more. I will finish building up this board and can send it to you. Do you need the heatsink? Do you want me to send the other board?

 

[MikeW]

probably that is why you need that high C10 and C11 (130 pf)
I made a mistake ordering two boards, I should order more and help you to tame it. Nevertheless, you can send me working board and I'll measure it with AP/check stability, etc

Do you have a power supply?

 

[dimitri]

Do you have a power supply?

 

[dimitri]

Mike, see how are C10 and C11 (130 pf) killing the amp (OLB)

 

[MikeW]

I took out the 130 pf and changed them to 22 pf.
I have taken C9 out. I have the other channel built and working.
The second one is always easier.
One board has Sanken outputs the other Toshiba. I will send you the 4 pair of extra Toshiba's if you would like to change them out. I have 2 caps to solder in when I take the boards off the heat sink.
Do you need heat sinks?
I can send the boards this week.

Thanks, Mike

 

[dimitri]

Please mention Toshiba and Sanken pairs, I'll check my piles. What are the minimum overall dimensions for the heatsink? I have different ones and I can use forced cooling. The only inconvenience is the absence of drilling press at home.

 

[MikeW]

You will need one that will be good for 80 to 100 watts. I will send you the one that I have used for testing. It got up to 50 deg C after 30 minutes. It was dissipating 112 watts.

 

[MikeW]

Let me know when you get the boards. Good luck.

 

[dimitri]

They are here. Assembling the power supply.

 

[MikeW]

How are you doing? Better than yesterday?

 

[dimitri]

much better

 

[AndrewT]

You will need one that will be good for 80 to 100 watts. I will send you the one that I have used for testing. It got up to 50 deg C after 30 minutes. It was dissipating 112 watts.

at what Vce?
Tc=50degC or Ts=50degC?
How far was this above the temperature de-rated SOAR for the test Vce?

 

[MikeW]

Temperature of the heat sinks. Enough above the SOA not to blow up anything.

After Dimitri's hard work we need to do some modifacations to the layout.

Updates coming.

 

[john curl]

Just turn down the BIAS to fit the heatsink. I do it all the time.

 

[bear]

TURN DOWN THE BIAS????

At last we have sure proof that the mad genius Curl has at last gone completely daffy!! PROOF I SAY!!

Nooooo... we don't turn down bias!!
Turn it UP! Then we pipe in the liquid Nitrogen coolant or the heatpump, the giant Peltier device, or ultra high velocity screaming turbo fans!!

Everyone with an ounce of experience knows that we want to use the smallest possible device and transfer heat away - an old metal can three legged thingie is ideal!! GIVE ME GERMANIUM IN A METAL CAN I SAY!!

Ok, now I have to take my little blue pills...

_-_-bear

 

[GRollins]

Bear,
I prefer the little white ones, myself.
Indeed...bigger heatsinks are the moral equivalent of using a bigger hammer when faced with a mechanical problem. Running hot? Hit it with a bigger heatsink!

Grey

 

[john curl]

Bear, they should have calculated the heatsink capacity better from the get-go, and I only offer a reasonable compromise for the moment. It will be enough to get them started. I know from the size of the heatsink that I used in 1968 to make my first amp of this topology. It now resides in a drawer, with the associated circuit attached. It would do about 15W, which was more than enough for my K-horn at the time.

 

[jacco vermeulen]

I want whatever the Bear is drinking.

 

[MikeW]

Bear, they should have calculated the heatsink capacity better from the get-go, and I only offer a reasonable compromise for the moment. It will be enough to get them started. I know from the size of the heatsink that I used in 1968 to make my first amp of this topology. It now resides in a drawer, with the associated circuit attached. It would do about 15W, which was more than enough for my K-horn at the time.

Don't make me laugh.
That heatsink was for testing. I have 10 more and 4 fan assembies if the unit gets to hot.
The circuit needs to be changed a little to work better.