[cat6man]

@wink
@frankcooter
 
hi,
i still have problems but am going to try to learn some transistor 101 first (it has been a long long while) and see
if i can figure it out. (wishful thinking?)
 
i may ask for some voltage measurements from someone with access to a hybrid for comparison.
 
i'm sure the facts that a) both sides behave the same and b) i'm getting 100V from output to star ground
are pretty big clues........either something was done wrong on both boards identically or something
similar died (poor handling of static sensitive devices??) but 100V at each outputs to ground should be a biggie.
 
another option is to bring it into one of our labs at work and have some 'transistor' buddies look at it..........they
build high power transmitters and low noise preamps for a living, so this should be easy for those folks
 
thanks again for asking, and i'll let you know how it goes and if i need more help here.
 
best
 

 

[studeb]

i saw that mouser seems to be out of all fairchild parts, esp for this amp.
Are they available elsewhere?

 

[ujamerstand]

cat6man, let me know if you need any voltage measurements from my hybrid.
 
studeb, mouser has MPSA92 from other manufacturer in stock. digikey has MJE340 and MJE350 in stock. You can find the N channel mosfet on ebay. 

 

[chinsettawong]

Hi,  
 
I've finished putting everything together.  When testing the amp, sometimes I can adjust the two output terminals down to zero, but once in a while the voltage on these terminals jumps up to around 190V.  I noticed that if I touch the input terminals using the probes of my multimeter, the voltage on the output terminals go back down to where it should be.  I'm confused.  Is this oscillation?  Do hybrid boards require grounding of the heatsink?
 
Wachara C.
 

 

[HiGHFLYiN9]

Quote:

TAW has the 10% version in stock

Looks like they're fresh out of both now. I may have to wait a month for mouser to restock as I can't find it elsewhere.
 
Boy, that TAW website is about as unintuitive as they come.

 

[sachu]

^^ buggers..for real?? Are there no other alternates for this part? Can we use this cap instead?

 

[ujamerstand]

^^ I've got that one. It was too fat.
 
Did you try emailing them? The website may not reflect their real inventory...

 

[sachu]

i should be able to mount the two diodes on the bottom of the board and slot it in somehow. I called TAW..no dice on the ones on the BOM. In any case, i just ordered 4 of the fatty ones..all i got now is hopes and dreams that I will be able to fit tem on the board unless there is some other alternative. Should possibly check other vendors. Vishay and kermet are out of these caps too.

 

[sachu]

I should think we might be able to get away with a polyester cap in this position eh? Something like this maybe?

 

[sachu]

hmm some serious diggin in my parts bin and i came up with one of the BOM capacitors..anyone got another? And i went ahead and cancelled that TAW order for the fatty MKP10 ones.

 

[ujamerstand]

I think I got 2 lying around... I was going to use them for a T2 style bias supply, but since the onboard one seem fine after listening to it for days, I don't think I'll need them anymore. I'll see if I can find them when I get home.

 

[sachu]

^^ sweetness!!..thanks dude

 

[ujamerstand]

It turns out I got 4 of these things lying around. 3 5% and 1 10%.  This cap is for the C6 position on the power supply. If anyone needs them I'll gladly pass them on.

 

[HiGHFLYiN9]

Can I trouble you for one ujamerstand? ygpm.

 

[drclaw]

YHPM ujamerstand.