Babelfish ᄅſ....or FW J2 on Steroids .... or Not your Father's J2!

[Dennis Hui]

The SMD pads seem to be on the back of the PCB.

 

[Zen Mod]

one Canuck is blind , same as Moi

second one is not



post #3 , pic repeated here , specially for blind and lazy ones

you'll see them populated, little later ....... supper time

 

[twitchie]

one Canuck is blind , same as Moi

second one is not

Guilty as charged

Just so you know MZM, I bought a hot air rework station because of you. Inspired by you of course and also because it was inexpensive and looked like a good idea at the time ...

 

[Zen Mod]

as I promised (to my self , in first place ) , today I did change pair of 2SK170BL in input LTP position , for 2+2 pcs of 2SK2145BL

previous idea was to up LTP current from 10mA to 20mA , resulting in healthy 50mW per tiny bugger , but later decided to try Papa's approach , of doubling input JFets , while Iq keeping at same level as for single pair

that way - due to increased combined xconductance , OLG is rising , and without change of NFB network , NFB is rising , so we can expect lower level of THD

is it good thing or not - sound wise , who cares ...... I have all the time left to humanity to try that ...... later

 

[Zen Mod]

now the real stuff ...... I mean - hard data

(observe how I finally switched two cells On , so removed confusing unnecessary part of graph )

each graph is having title in bottom

so , THD indeed goes down , comparing to yesterdays measurements , with pair of Toshiba 2SK170BL in FE

load 8R

 

[Zen Mod]

same , load 4R

 

[Zen Mod]

tomorrow - Semisouth SJEP in bottom position , 2SK2145BL will stay in , no reason to change them anymore

it just came to my (precious!) mind - I can try Pass SIT-1 there , too......

naah , too complicated , involving depletion part .....

 

[Dennis Hui]

Bad ZM!

 

[Zen Mod]

nope .

Papa is baaaaaaaaaad!!

 

[Zen Mod]

having some time before actually being forced to sleep

it's interesting to put them (graphs) side by side and compare

so , left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

1W@8R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

5W@8R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

10W@8R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

20W@8R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

25W@8R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

Freq. response @8R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

1W@4R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

5W@4R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

10W@4R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

20W@4R

 

[Zen Mod]

left is FE with pair of 2SK170BL , right is FE with double pair of 2SK2145BL

LTP Iq 10mA in both cases

Freq. response @4R



good night .........