Source resistors for MOSFETs

jackinnj · 24th December 2008, 01:28 AM

Just some pix of the results of 2 source resistors for a MOSFEt amplifier like the F4 or F5 -- the results are "normalized" and the setup identical using an HP3577 network analyzer. The first is the Mills 0.47R, the second is an Ohmite TWW5 series:

lineup · 24th December 2008, 01:36 AM

and what does it show?

distortion of some kind per frequency, maybe

Nico Ras · 24th December 2008, 06:04 AM

Propagation loss

AndrewT · 24th December 2008, 02:30 PM

come on you two, explain it for us.

mlloyd1 · 24th December 2008, 03:27 PM

are these the same mosfet source resistors we want to be non-inductive?
and we are seeing impedance vs frequency?

hmmmm .....

mlloyd1

SpittinLLama · 24th December 2008, 03:46 PM

I thought we did want them to be a little inductive for stability. The plots sure look like impedance plots to me.

-TH

jackinnj · 24th December 2008, 03:58 PM

It's transmission vs frequency --

EUVL · 24th December 2008, 04:54 PM

How about Caddock MP930 ?
You do use them, right ?

Patrick

jackinnj · 24th December 2008, 05:01 PM

I've used the Caddock's on the F5's I have built. I didn't put them to the test -- yet -- see below 100 ohm MP915

For the source resistors, the 15W should suffice, no?

syn08 · 24th December 2008, 05:23 PM

Quote:

Originally posted by jackinnj
I've used the Caddock's on the F5's I have built. I didn't put them to the test -- yet -- see below 100 ohm MP915

For the source resistors, the 15W should suffice, no?
[/img]

C'mon Jack, you are comparing apples and oranges. Caddock's MP915 are thick film, others are wire wound. The differences between the wire resistors is most likely due to the winding technology.

I'm using MP915 in the feedback loop for YAP, with very good results.

24th December 2008, 01:28 AM	#1
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Source resistors for MOSFETs Just some pix of the results of 2 source resistors for a MOSFEt amplifier like the F4 or F5 -- the results are "normalized" and the setup identical using an HP3577 network analyzer. The first is the Mills 0.47R, the second is an Ohmite TWW5 series:

24th December 2008, 01:36 AM	#2
lineup diyAudio Member Join Date: Dec 2005 Location: the north	and what does it show? distortion of some kind per frequency, maybe __________________ lineup

24th December 2008, 02:30 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	come on you two, explain it for us. __________________ regards Andrew T.

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24th December 2008, 06:04 AM	#3
Nico Ras diyAudio Member Join Date: Nov 2005 Location: Amanzimtoti - East Coast of South Africa	Propagation loss

24th December 2008, 03:27 PM	#5
mlloyd1 diyAudio Member Join Date: Feb 2001 Location: illinois	are these the same mosfet source resistors we want to be non-inductive? and we are seeing impedance vs frequency? hmmmm ..... mlloyd1

24th December 2008, 03:46 PM	#6
SpittinLLama diyAudio Member Join Date: Apr 2005 Location: In the Wild, Wild West	I thought we did want them to be a little inductive for stability. The plots sure look like impedance plots to me. -TH

24th December 2008, 03:58 PM	#7
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	It's transmission vs frequency --

24th December 2008, 04:54 PM	#8
EUVL diyAudio Member Join Date: Oct 2003	How about Caddock MP930 ? You do use them, right ? Patrick

24th December 2008, 05:01 PM	#9
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	I've used the Caddock's on the F5's I have built. I didn't put them to the test -- yet -- see below 100 ohm MP915 For the source resistors, the 15W should suffice, no?

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