700 Series II Clair Originality

[grapplesaw]

Lower supply current requirements for the LF351 than the original LF356 plus they originally overprovisioned the necessary supply current needs of the LF356 which resulted in PC boards that turned brown at the connection points and ruined the etch from the heat dissipated by the original dropping resistor. Common problem on that PL36 board.

Thank you Joe

So how critical is this value.. I am asking because the d-500 uses a 3k resistor withe lf356 ic, higher rail voltage at 120v
If we use a bb oap134 , or as what I want to do , use a dual bb oap 2134 will the 7.5k be all that is required?

Glen

 

[grapplesaw]

Thank you Joe

So how critical is this value.. I am asking because the d-500 uses a 3k resistor withe lf356 ic, higher rail voltage at 120v
If we use a bb oap134 , or as what I want to do , use a dual bb oap 2134 will the 7.5k be all that is required?

Glen

What is best type resistor, wire wound hollow, cement encased or aluminum jacketed or film type

 

[Gepetto]

Thank you Joe

So how critical is this value.. I am asking because the d-500 uses a 3k resistor withe lf356 ic, higher rail voltage at 120v
If we use a bb oap134 , or as what I want to do , use a dual bb oap 2134 will the 7.5k be all that is required?

Glen

Each OPA style amp draws a max quiescent current of 5mA per amp. If you have one op amp per channel you will need to provision 10mA which would require a 10K dropping resistor to the 15V zener to just maintain regulation.

3K is overkill but 5K-7.5K 5W would be a good choice.

 

[Gepetto]

What is best type resistor, wire wound hollow, cement encased or aluminum jacketed or film type

This is just a shunt regulator bias resistor so your preference should rule. The cement ones are flameproof in the event of a short so may be the best choice.

 

[grapplesaw]

This is just a shunt regulator bias resistor so your preference should rule. The cement ones are flameproof in the event of a short so may be the best choice.

Again many thanks for the update Joe

 

[oldphaser]

So while we are asking Questions

What is the reason for the change of the Dropper Resistors on Phase Linear Control Boards R1, R2 from 2.7K/5W to 7.5K/5W when changing the op amp lf356 to lf351

Both these op amps are 15 volt units and similar min max voltages?

Is the current draw less with one thus the different resistance?

Please enlighten me.
thanks
glen

Glen,

I just got back from Dean's house and asked him about this.

Joe is right about "Lower supply current requirements for the LF351 than the original LF356"
Apparently the LF351 also has a higher output impedence as well.
If you don't change the resistors from 2.4K to 7.5K you will cook the zener diodes.

Ed

 

[oldphaser]

Clair Brothers Spec for Phase Linear 700 Series Amplifiers

I was finally able to obtain from Dean a copy of the Clair Brothers spec for the 700 series amplifiers. (see attached documents)


The spec originated with the 700B.


I scanned the document twice since part of the data on the edge of the page was cut off.


I apologize but the copy Dean has is a poor copy of the original.


The names on the bottom of the page are:


Geo. (which is probably George Sheppard, production line manager)
Gary (perhaps Gary Clark)
T. Pennington (Terry Pennington, engineer)


I asked Dean about the existence of any black face Clair Brothers 400's and he said there wasn't any.

It appears after loading these (2) documents that the size is pretty small. Perhaps Lee, Joe or Perry whom I also sent copies to could load a larger version somehow.

Ed

 

[Northwinds]

Awesome Ed!!!! Can't wait to see the images bigger!!

 

[WOPL Sniffer]

Let see if I can blow them up...........

 

[Gepetto]

Let see if I can blow them up...........


View attachment 26199 View attachment 26200

What they really wanted back then is what they can get now...

 

[laatsch55]

That and some bigger heatsinks....