F5 power amplifier

[udailey]

A blob of that arts/crafts glue stick stuff that you put in a gun and heat it up so that you can spread it ... if you seal them together with this they will stay the same temp as the glue will act as a heatsink and will heat up evenly. No.. it wont get warm enough to turn back into glue.
Ri

[tinitus]

If the Jfets are glued into a massive chunk of aluminium, the temperature will just be below that of the inside box, 100% stable, always

I have considered this before, but thought it was much too impractical, in many ways

But the solution is quite simple
Place the Jfets horisontal
Then the massive heatsink can be screw mounted

Oh, yeah, drill a few exstra holes fore future mods, like a cascode

[fishski13]

i made some progress tonight - doin' it the "big dumb way".. 33,000uF Panny UP x4. Panny power resistors. red G-10 board is 3-1/8 by 6-3/4. block rectifiers will flank the board, mounted directly on the chassis bottom.

[udailey]

Looks 'smart and compact' to me. Nice job man.
Uriah

[osscar]

Nice PSU , im still working with enclosure (sanding, dtilling ...boring) i hope amp will be ready till end of next week.

[Ryssen]

Originally Posted by Nelson Pass

I find that the most important details relate to the bandwidth.
The typical - 3dB point is out around 1 MHz, so without
compensation you can see all manner of effects.

Any time there is a question about this possibility, it's helpful
to throw a small capacitor across the feedback resistors and
see if it changes anything.

I had to limmit the bandwith because I got oschillation(uncuntrolled heating)when connected to a DAC via transformers.Anyway I used a 2,2nf across R10 and that stopped the oschillating(heating)but I think I got some less detals after,can the 2,2nf cause that?Should I use a smaller cap to keep out of the hearing area?

[alazira]

Originally Posted by Ryssen

I had to limmit the bandwith because I got oschillation(uncuntrolled heating)when connected to a DAC via transformers.Anyway I used a 2,2nf across R10 and that stopped the oschillating(heating)but I think I got some less detals after,can the 2,2nf cause that?Should I use a smaller cap to keep out of the hearing area?

Hi Ryssen,

I think R10 is a ground reference, not part of the feedback. To limit the bandwidth the cap needs to be on R5 and R6 (plus R7&R8 if used). Perhaps you can also consider increasing the gate resistors (R9, R13, R14) to see if it fixes the problem? Trimpot might be a friend here. If I'm mistaken (quite possible as my grasp is tenuous) someone please correct me.

Garrett

[tinitus]

Correct, it is R6-8
I was recommended a cap in the pf range, but to be checked with instrument
I suppose that if you mount the wrong size cap you will just get a "ringing", and still have not dealt with the problem
Isnt 22-100pf often used
100pf is like 0.1nf, right

If you use multiple outputs, its also been adviced to increase R11/12 source resistors to maybe about 1ohm

[Ryssen]

In the manual it says"You can limit frekvency responce by an input capacistor across R10,and allso in the feedbackloop with capasistance across R5 and/or R8,i have choosen not to"

I tried caps across R5 and R8 with no effekt on the problem,cap across R10 had effekt,maybee to much...

[tinitus]

Originally Posted by Ryssen

I tried caps across R5 and R8 with no effekt on the problem,cap across R10 had effekt,maybee to much...

Ofcourse, it makes perfect sense
R9 and R10 are there exactly to deal with problems like yours, oscillation caused by a connected source