JLH Mosfet Power amplifier construction thread

[jamesfeline]

Enjoying this thread; I always lusted after building a JLH mosfet amp, but never could afford the Hart kit way back when.

I built both versions of JLH's 69 and 96 amps.

Hello mosfetDemond ...

thanks for the nice comments what did you think of the 69 / 1996 class A amplifiers .. this was my next build as I have never made one yet ..

 

[mosfetDemon]

Fabulous !
JLH was a legend.

 

[jamesfeline]

hello Nearly completed the power supply

 

[jamesfeline]

underneath the pcb I ran separate supply cables to the current sensing resistors

 

[jamesfeline]

last batch of pictures

 

[jamesfeline]

Hello ...

started to make the power amplifier... progress to date

 

[jamesfeline]

and some very rare transistors

VN1210M .. remember those ?

 

[jamesfeline]

And the BF870 .. from Philips

 

[ctrlx]

when you have a pa board up and running, i would be interested to know what its clipping performance is with a 10KHz sine.....

 

[jamesfeline]

when you have a pa board up and running, i would be interested to know what its clipping performance is with a 10KHz sine.....

ok will do .. will let you know

 

[jamesfeline]

Hello .. well the PSU all works, this PSU is a great little regulated unit .. that works great with common components, but as said this is a pure test bed to check newly constructed PCB's

 

[jamesfeline]

slow progress on the power amplifier ..

 

[kannan_s]

Hi
do you plan to sell the kit of parts from your stock?
kannan

 

[tonewheelkev]

Hi James
...plan to introduce fuses, as per your pics, to protect transformer 2ndary (and Primary if that's a good idea?).....not prepared to see another one hit the fan!


How would I go about selecting fuse values please.....haven't a clue where to start here...??...


Also...you mentioned the Hart construction manual last week...did you manage to find it??


Kev

 

[jamesfeline]

Hi
do you plan to sell the kit of parts from your stock?
kannan

Hello

Probably not .. but happy to make a basic kit that would include the PCB / rare original transistors & instructions (updated with mods)

As most if not all the caps / resistors are available form local sourced component outlets .. but yes this is something I have been thinking about

all the best

 

[spm]

Hi.
Do you have any boards available?
I still have my original amplifier, but time has not been kind to the PCBs or some of the resistors and even though thoroughly cleaned, the PSU keeps tripping and there are a variety of variable faults in the power amp boards.
I'd like to rebuild them if possible.
If not, I could just strip them back and start again, but new boards would be nicer.
Let me know.
Best wishes
Simon

 

[jamesfeline]

Hello
I could probably spare 2 power supply and 2 power amplifier boards if that helps ?
any pics of you amplifier

 

[spm]

It’s condition is an embarrassment...
Mine is a stereo unit.
Let me know how much I owe you for the boards.
Simon

 

[jamesfeline]

hello

bloody hell ... where has that been, in the garden shed for the last 20 years

 

[tonewheelkev]

It’s condition is an embarrassment...
Mine is a stereo unit.
........

Hey spm....if you decide to break that down for parts....I have a very good home for the toroidal transformer (...in a poorly Monoblock version!! )