Hello Billhurst,
are your thermistors in good contact with the plastic case / surface of the Mosfets? Don't bend them to the metal washers on the Mosfets. The thermistors are well known to easily become damaged on the surfacecoating / colour.
If your new JFets have different values like your original ones - this could also explain a difference in the overall bias.
I would check the thermistors. You describe it as heating up equally , then one side goes / regulates down.
Only an asssumption from me.
And 20mV difference in bias is not so far away.
Cheers
Dirk.
are your thermistors in good contact with the plastic case / surface of the Mosfets? Don't bend them to the metal washers on the Mosfets. The thermistors are well known to easily become damaged on the surfacecoating / colour.
If your new JFets have different values like your original ones - this could also explain a difference in the overall bias.
I would check the thermistors. You describe it as heating up equally , then one side goes / regulates down.
Only an asssumption from me.
And 20mV difference in bias is not so far away.
Cheers
Dirk.
Take a look at posts #6982, 6993 & 6996, esprit was able to increase bias using 8 -11mA IDSS JFET's. Since you are NOT using the diodes, and your heat sink temps are OK, your DC offset is close to 0 mV it sounds like the JFET's are limiting max bias.
I am laying out the components for my F5T build. I use a case with with long heatsink fins and the case internal width is relative small. This makes the 2 400W transformers to be placed very close together. Is there a recommended minimum spacing for torroidal transformers? Or I should stack them one on top the other?
Toroidals are fine to be bunched up together given their very narrow EM field, you can put a shield on them too
Stacking is fine too
Stacking is fine too
Hello everybody, I am considering selling a pair F5 turbos V3 (monoblocks) they are well built, in deluxe U5 chassis, the front boards are built with vishay 1% resistors, real toshiba fets, why? I have a X250.8. Big power supplies with 432000 uF of RCR filtering (too much?), Antek 800 VA transformers. How much should be fair to ask for the pair? Thanks.