Ben's (BubbaH's) Phase Linear 400 WOPL conversion

[laatsch55]

Right channel done...I like the way Glen (grapplesaw) ran his control wires....thought I would try it too....

 

[laatsch55]

Control board done.....now on to a row of outputs...

 

[laatsch55]

Power up is a rather strange one....NO BIAS VOLTAGE...zilch, nada...16mv offset, and no bias...

 

[laatsch55]

And ya won't have any bias with the 2N5088 soldered in the 2N3403 holes....jeez...

 

[laatsch55]

And 5 minute epoxy is not really 5 minute epoxy....

 

[Northwinds]

And 5 minute epoxy is not really 5 minute epoxy....

LMAO!!!!!!!!!!

 

[NavLinear]

And ya won't have any bias with the 2N5088 soldered in the 2N3403 holes....jeez...

In my experience it is important to put it in the right hole. You just might get bias when you don't need it!

 

[laatsch55]

I had to cut the bias transistors off the backplane and put new ones in the P-strap. Then epoxy them in. And we are waiting cure time. Should power up just fine after that. Had only 16mv DC offset so everything else is a go...

 

[laatsch55]

In my experience it is important to put it in the right hole. You just might get bias when you don't need it!

Yep, definately a misbiass as opposed to halfbiass.....where's D2 when ya need him...

 

[MarkWComer]

Power up is a rather strange one....NO BIAS VOLTAGE...zilch, nada...16mv offset, and no bias...

Are you measuring bias on the control board or on the backplane board? Remember from Nelson's build: TP1 and TP2 are mislabled on the board- the designations should be reversed.

 

[laatsch55]

Yes Sir, I remember that. I had the 2N5088 soldered in the 2N3403 holes..

 

[laatsch55]

After putting in the 2N5088's I still had a bias problem. Was only getting 33 MV of bias. Evidently when you put 2N5088 in the wrong place,,,it wipes out R4 on the backplanes also, a 1/4watt, 1ohm resistor...

 

[Gepetto]

After putting in the 2N5088's I still had a bias problem. Was only getting 33 MV of bias. Evidently when you put 2N5088 in the wrong place,,,it wipes out R4 on the backplanes also, a 1/4watt, 1ohm resistor...

Yes Lee, that is your runaway protection (fuse) from excessive bias current in the event that Q6 fails open. If Q6 fails short, then no harm will occur, just no bias will exist.

 

[laatsch55]

Nice feature Joe....makes for an easy fix...

 

[Gepetto]

Nice feature Joe....makes for an easy fix...

It beats replacing blown Q7 and Q10

 

[laatsch55]

Indeed Joe!

 

[derek92994]

Half Biasss!!

 

[laatsch55]

And Ben's amp is on the horns----Shpongle---" Corridor of Mirrors" first up.....AND LOUD!!!

 

[laatsch55]

And it sounds damn good!! Vibrating the ol leg BY GOD!! Maybe that'll fix it!!!!

 

[derek92994]

Ahhhh Full Biasss!