codyt- I'm still jammin the SIT-3! It's a keeper along with the J2. Still gonna build an F6 when time allows
zm- I'm smiling alright. I've never measured bias before today and you got me over that mental hurdle
zm- I'm smiling alright. I've never measured bias before today and you got me over that mental hurdle
I was trying to find some more j109 so that I could pursue building a pair of stereo J2 for the multiway horn system I have been wanting to try with an active crossover.
I broke down and ordered matched octets of J74 instead from a trusted seller on eBay.
They were supposed to be BL grade 7-8 mA matched within .03mA/4mV.
I got packages labeled 8.6 and 8.7...which I haven’t opened yet. Inner packaging seems also labeled 8.xx Idss on bags.
This seems kind of high on the end of the BL 7-8 mA scale.
Will I have an issue with them in the J2?
I broke down and ordered matched octets of J74 instead from a trusted seller on eBay.
They were supposed to be BL grade 7-8 mA matched within .03mA/4mV.
I got packages labeled 8.6 and 8.7...which I haven’t opened yet. Inner packaging seems also labeled 8.xx Idss on bags.
This seems kind of high on the end of the BL 7-8 mA scale.
Will I have an issue with them in the J2?
Thanks Jeff
Started work on cases...trying to make lemonade with what I have.
I think my Mouser order is sorted except for a few other items I might want to replenish.
Onwards!!!
Started work on cases...trying to make lemonade with what I have.
I think my Mouser order is sorted except for a few other items I might want to replenish.
Onwards!!!
I had a target of 8.5 total. My sims showed a pretty shallow sweet spot though, so I'm not sure it matters much. (And then there's the fact that sims never perfectly match reality, and I didn't do any actual testing with different currents.)
Who noticed there are some J2 with SemiSouth JFET E120R100 marked T1034 which is the same code used in the Semisouth Pass SIT-1. Does it mean anything? Also does anybody know if the the use of 2 x SJ109 BL vs. 4 x SJ74 (as in the later J2s) for each channel translates into any sonic difference? Cheers
I asked Punkydawg on eBay about GR K170...no dice.
He does have GR J74.
He also said you can request matched BL 2sk170 from the low end of the range...say around 6 mA.
I was just surprised he sent me the octets in the high 8s because I interpreted the 7-8mA range being between 7.0 and 8.0...not 8.9.
He does have GR J74.
He also said you can request matched BL 2sk170 from the low end of the range...say around 6 mA.
I was just surprised he sent me the octets in the high 8s because I interpreted the 7-8mA range being between 7.0 and 8.0...not 8.9.
I decided to just order Panasonic 3 watt ERX instead of the pricey Ohmite TNP10...I have a couple sets of shorter PCBs I’m considering using that aren’t designed for the Ohmites. The short boards might be used because of my case situation.
If the ERX are good enough for Pa...
Only other thing I was doubtful on was choosing the 4N35 opto. So many popped up when I searched Mouser. I wasn’t sure if there were any specs they had to meet other than being through hole and made by a company I recognized.
I picked the first Vishay in the list...
4N35-X000 Vishay Semiconductors | Mouser
Any reason not to use them?
If the ERX are good enough for Pa...
Only other thing I was doubtful on was choosing the 4N35 opto. So many popped up when I searched Mouser. I wasn’t sure if there were any specs they had to meet other than being through hole and made by a company I recognized.
I picked the first Vishay in the list...
4N35-X000 Vishay Semiconductors | Mouser
Any reason not to use them?
Last edited:
Hi ZM,
sorry for the late answer I'm too busy at work ...
My measurements after changing the iso pads to al-oxyd with heat-conducting paste after around one hour (opening the lid only for short measuring).
Build with IRFP150 & SJEP120R100
heatsink: ~ 65°C
case of SS: ~72°C
Drain: 82°C
Ofset: 0,9mV / 1,1mV
Seems to be in a "normal" range. :-( Any thoughts?
sorry for the late answer I'm too busy at work ...
My measurements after changing the iso pads to al-oxyd with heat-conducting paste after around one hour (opening the lid only for short measuring).
Build with IRFP150 & SJEP120R100
heatsink: ~ 65°C
case of SS: ~72°C
Drain: 82°C
Ofset: 0,9mV / 1,1mV
Seems to be in a "normal" range. :-( Any thoughts?
even if heatsink temperature ( near transistor itself) seems somewhat higher than I'm expecting, everything looks normal
one thing, as desperate ones are reaching even for a leaf, why not putting IRFP240 in place of SS, and see what's going to happen in month or two ?
one thing, as desperate ones are reaching even for a leaf, why not putting IRFP240 in place of SS, and see what's going to happen in month or two ?
Thanks ZM,
will try IRFP240 in place of SS, any other changes needed (adjustment is clear)?
Can't post schematic, it looks like papa style. ;-)
will try IRFP240 in place of SS, any other changes needed (adjustment is clear)?
Can't post schematic, it looks like papa style. ;-)