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F5 pcb group buy...

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#424
F-5 assembly and static charges

Ok, I have noted warnings about the outputs and apparently the MUR 3060 diodes I'm using concerning static charge. All of these pieces have remained in their packaging since arrival.

What precautions need to be taken in the handling of these pieces? I havent really read anyone talking about this, maybe its not as big a problem as I'm making it, but I'm sure there are some do's and dont's...

thanks in advance,
Russellc
 
#425
Thermistors TH1/2

Peter,

Having built my F5's (and blown them up - mosfets in the wrong way!!) I have rebuilt them but this time I do not have the mosfets directly in the boards - there are short (2 inch) leads from the board to the devices. Setting the bias was straightforward with little drift.

However I am a little worried about the temperature tracking thermistors which are in their original place on the board - so will there effect be reduced? Should I move them to be closer (on top?) of the fets?

The heatsinks are overkill for the amp and are running cool.

Alan
 
#430
F5 up and running

Peter,

I got my F5's up and running - blew up a few things on the way and had to use my spare set of boards. I removed the temp compensation components and I have to say that this is a beatiful sounding amp which seems to be getting better day on day.

Alan
 
#432
Boards showed up today Peter, beautiful, I'm glad I ordered another set. Thank you very much for the extra rectifier boards, they are very much appreciated!
I was going to build an F5 P2P, but these will add a very elegant touch.

Have all my parts except for heatsinks and N-channel MOSFETS.

This will be my first DIY amp - can't wait to hear this thing.

Thanks again,
Scott

All hail Nelson Pass!
 
#436
Hi Androuski,
According to the designer himself, the JFETS need not be tightly matched, but do need to be in the same grade, preferably 'BL'. Recommended IDSS for the standard circuit is about 8mA. Many members on the board DO match these devices for optimum results.
In other words: match if you can.

Personally, I got lucky and even partly decided to build an F5 because I have had 20 each 2SJ74BL/2SK170BL from ampslab.com just laying around for almost 2 years - all measured and matched.

It's sweet when you have the toughest parts to get in your parts bin!

One last note:
I have been scouring the threads for information on building an F5 with Toshiba 2SK1530/J201 outputs, one mod I have heard is using 6mA IDSS input fets rather than 8mA, any info is much appreciated, although any respondents should probably post on the F5 builders thread....

Scott
 
#439
Peter Daniel said:
Of course there were PS boards for this one as well, but during last few months all have been sold out.
Click to expand...

Hi, I am in the process of building this board, having already built the cviller versions.

I notice that the power supply PCB does not have provision for R9 and R10 as shown on the schematic found in Nelson Pass' service manual for the F5. If I remember correctly the value is 2.2k 3w.

Are they not required, or added elsewhere?
 
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