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Interest for potential GB for UDNess PCBs and matched FETs.

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#41
It seems I'm late to the party ... hoping to have a chance, I've added my name. Thanks!


ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
 
#42
Interested at pcb set shipped to EU

ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
samoloko 1 pcb set
 
#43
Things move quickly around here. . . But if so inclined to add more I would love to participate!

ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
Billyk 1 Set
 
#45
if lucky and these are available...

ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
Billyk 1 Set
BuzzLiteYr 1 pcb set (would take 2 extra sets pcbs for a total of 3 sets)
 
#46
ItsAllInMyHead 1 set
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
samoloko 1 pcb set

Billyk 1 Set
BuzzLiteYr 1 pcb set (would take 2 extra sets pcbs for a total of 3 sets)
 
#47
Hi All -

Apologies for not providing an update in a few days.

All parts and boards are ordered. 😀 I am waiting to hear back from JLCPCB re: firm timing. I used DHL for shipping. However, they sent an advisory re: the coronavirus and potential delays. So, I'm crossing my fingers and wishing everyone there is healthy and that they'll remain so.

Once I have boards in hand or a firm date, I'll let everyone know.

I'll also get in touch with everyone re: addresses etc. once I have a bit of time.

:cheers:
 
#48
Hi All -

This may not be the perfect place for my question, but you all have a vested interest in me doing things properly... 😀 I've been looking into how to improve my matching process and techniques.

I started down the rabbit hole by searching references for the Peak DCA55 and DCA75 since the jig Patrick recommended for the SOT-23 parts was created by the same company and intended to be paired with it. Then... I searched the forum for curve tracers / how to match etc. I'm willing to make an investment for this and future projects to make my work go a bit more quickly and get more reliable / repeatable results. No costs passed on.

It seems one limitation of the Peak devices mentioned is max 10V / 0A010. So, it is not suitable for the output devices (I think). Do any of you have a recommendation for a thread or two I could read or any specific device(s) I could build or buy for properly matching a range of FETs like for our build?
Budget needs to be ~$200USD or less. I'm not ready for an APXXXX 😱

Something like the DCA75 seems ideal for a person like me in terms of UI and ease of overall use, but it doesn't seem to have the capability we need for at least one of our parts. I had been using a DMM, a lab supply, and a jig for all my previous builds. Those went well, and my process was reasonably efficient, but if there's a better (?) way...

Suggestions appreciated. I can also move this to a new thread if it clogs things up here.
 
#49
There were some questions about matching.

It has been mentioned many times before, including how to measure a number of parameters using just a DMM, etc.
FET Measurements with Just A DMM

But for the purpose of the UDNeSS,
J113 -- match Vgs at 6mA
2SK209GR --match Idss and optionally Vp
FQA9P25 -- match Vgs at 1.3A.

You can refer to Fig. 5 of Borbely :
JFETs: The New Frontier, Part 1 | audioXpress

And for MOSFETs :
PassDiy

Of course there are more sophisticated methods.
But it is not relevant for your purpose here.


Cheers,
Patrick
 
#50
Hi Patrick - Greatly appreciated! I'll review everything again. I have read all but the AudioXpress article.

Note to all - I have everything but the boards and the output FETs. So, work should begin after a bit of reading tomorrow.

:cheers:

Patrick
 
#51
Update -

I have received all PCBs. Looks like things are starting to flow slowly out of China. They look great. Thanks to all for the recommendations for sourcing.

I think I have everything I need for matching all but the 2SK209s. I should be able to get started matching and sorting this weekend.
 
#56
@bullittstang - Thank you very much for the ping.

All - I have been away for several weeks. My humble apologies. I started matching the Fairchilds, then ...

All is well, but I haven't been able to get any DIY done for quite some time. I hope to be able to get back at it this weekend. I have all the boards, all the parts, and the jigs. So I'm committed to getting it all done. I just need the time.

I hope everyone out there is happy and healthy. I'll do a better job of keeping on top of things.

😀

Patrick
 
#57
Delay / Pause Indefinitely

Hi Everyone -

My humble apologies. I don't want to string people on forever if you're dying to get this project off the ground ASAP.

Admittedly, I had to ask for some serious help re: how to build a constant current source to match the 2SK209s. I originally thought my lab supply would provide a constant current. It will, but not to any reliable level of precision at that low a current. I have the parts on order to build the current source.

I also matched the Fairchilds I had done at the wrong current... 😀 :headbash: :cuss: Live and learn. I'm getting it bit by bit. I now have big ol' "dummy load" sized resistors, a heat sink to mount the resistors, and a proper set up for the power level. I'll have to see if I need a heatsink for the FETs themselves at that power level. I confirmed the math with a trusted source, but I'll use 16 ohms (two 8ohm dummy resistors in series) at 24V to get us close enough. If that's not what was expected... or advised, please chime in. I'll start over on those.

I'll get to the point.

I have no idea when I'll get this done. All is well, but my time has been sucked elsewhere for the time being.

I have two options for those that have been patient enough to bear with me... and those that may want to continue. Heck, I thought I'd be done in Feb. Best laid plans and all that...

For those that are ALREADY on the list that have stuck with me... I have a few options for you.

Option 1 - Boards ASAP

For those in the US, I'll ship you a set of boards for a $10 or more donation to DIYA. For those outside the US - we'll work on actual shipping cost, but $10 will probably get it done.

If you don't already have a star under your name, I want to see one. My gift to you and DIYA. If you've already donated, I'll go on your honor that you'll add to it.

Option 2 - Stick it out.

I WILL get this done. I just can't promise a timeline, and I hate to keep posting.... one or two more weeks. It just ain't gonna happen quickly with my current commitments. I'll still post to keep you informed, but it could easily be June-July.

Heck, if you stick it out - I'll still do the $10 or more donation - with a much stronger encouragement for it to be more, but times being what they are - $10 gets it done 😀

Thank you for your patience.

I hope you and your families are safe, happy, and healthy.

:cheers:

Patrick
 
#58
I’m all in and in no hurry (just blew up an amp last night, so have something to keep me busy in the meantime)

Thanks for doing this - if you would be willing, I’d like to see and hear about getting the constant current source and testing done (helps me learn things to hear from those that have done it). Understand that’s another ask of your already limited time, so totally up to you.

Stay safe and thanks again!
 
#60
Great -Thanks Jens

Here is the latest list. If everyone will update theirs with what they've chosen. I'll give everyone some time. After a week or so, I'll PM those that have not updated to see what they'd prefer and/or if they're still interested.

BTW - this is not meant to be majority rules. Each person can choose, but not both. So, you can't have the boards now, and then wait for the complete set. Those that wanted extra boards / sets - we can talk off line later re: what's left over.

If you're choosing option 1 - PM me your exact shipping details. For international, I'll get back to you re: cost and your recommended best methods for shipping to your country.

For Option 2 - we can wait on shipping details.

------------------------------

ItsAllInMyHead 1 set - Option 2 Obviously 😀
Mark Johnson 1 set (+ as many as possible)
AnthonyA 1 set
OtisCampbell 1 set
bullittstang 1 set +(3+ xtra sets, & let me know if you have extra transistors)
myl 1 set
yoaudio 1 set
hirscwi 1 set
mordikai 1 set
zchopper 1 set
jens r. 1 set - Option 1
Astromo. 1 set
----------------------------------------------------------------------
mordikai 1 extra set, will take some unmatched transistors
myl 3 extra PCB sets
Touchdown, 1 set
samoloko 1 pcb set
Billyk 1 Set
BuzzLiteYr 1 pcb set (would take 2 extra sets pcbs for a total of 3 sets)
 
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