Walterw, i have done three circuits of this type and ever with voltages in this range. Try change transistors, or readjust all again from zero very slowly...
I used three sets of transistors, first was with KD33 and KF33 type and others with KE33. Try using other set of transistors.
I don't want to try another set....lots of work😀 Maybe the 2SJ28 is defective or out of spec ...
Maybe this explains my low gain ?
Maybe this explains my low gain ?
When you finish the other channel you can compare. If you can get an oscilloscope and simple function generator you can see how works. Have you many 2SJ28 and 2SK82?. Amplifier begin to distort equals between positive and negative power rail and round 17-18V, more or less. See the photo. There is not many elements that can fail.
Good luck
Good luck
Attachments
Thanks Jama, I looked again, and I think I can replace the VFET's pretty simple. I'll let you know the results.
And who cares, you'll see how to make money at the expense of new resources. We will not get to mourn as children, technology is changing and improving. Actually that provider is enriched by the presence of these forums.
I am afraid like you DIYspaceW.....
I wanna be a macho but I suffer like child when my just discovered Vfet scarce.
The problem is the carrot in front the jackass and in these times, with a little of indulgency i consider myself a little jackass behind of the carrot.
The consolation or the excuse is, Just there out door there are plenty of jackass behind of plastic carrots.
Forgiving partner rudeness. I felt like you.
Best Regards and take care, Indulgence of Mr Hal Pass gonna provide some solution.
I wanna be a macho but I suffer like child when my just discovered Vfet scarce.
The problem is the carrot in front the jackass and in these times, with a little of indulgency i consider myself a little jackass behind of the carrot.
The consolation or the excuse is, Just there out door there are plenty of jackass behind of plastic carrots.
Forgiving partner rudeness. I felt like you.
Best Regards and take care, Indulgence of Mr Hal Pass gonna provide some solution.
last night i had a dream ... with some re-wiring of the jensen secondary could we have two amp in one, one push pull class A vFET and one CCS load single ended SIT AMP with no output cap ? 😱 let me dream ...🙂
Yes, that's how I connected it, the two cases (drains) are connected from P and N channel VFETs and that's is loudspeaker out....
i 'm looking for a heatsink model for the amp any model easy to find ? i have only found KW/H indication what is the right value for one chanel ?🙂
rule of thumb :
((Ths-Tamb)/diss)/1.1 [K/W] or [C/W] , which is practically same thing
Ths=max 55C
Tamb = take 30C for summer
diss=dissipation per heatsink ( pne or both channels)
((Ths-Tamb)/diss)/1.1 [K/W] or [C/W] , which is practically same thing
Ths=max 55C
Tamb = take 30C for summer
diss=dissipation per heatsink ( pne or both channels)
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