ZTX450 for AX

kilowattski · 26th October 2004, 08:00 PM

I have been through this myself already. I can see any reason why I can't use the ZTX450 instead of the MPSA18 or BC550C in an Aleph X? Can anyone confirm this in case I may have missed some obscure reason.

Nelson Pass · 26th October 2004, 08:26 PM

No reason at all, at least not in this application.

Netlist · 26th October 2004, 08:30 PM

MPSA18: NF-ra,45V, 0,2A, 0,625W, 160MHz, B>500
BC550: Uni,ra,50V, 0,1A, 0,5W, 300MHz
ZTX450: Uni, 60V, 1A, 1W, >150MHz

The MPSA18 and BC550 are both low noice (ra) and if you take the BC550C they both have a high Hfe.

My guess is that all should work properly.

/Hugo

Oops, too slow for Nelson

EUVL · 26th October 2004, 08:38 PM

I am only quoting datasheet :

Tr Type Noise Figures Data Source

BC550 4dB Philips '99
MPSA18 1.5dB Fairchild '97
ZTX450 not quoted Zetex

Patrick

Nelson Pass · 26th October 2004, 09:26 PM

No question if this were an input stage device that the
ZTX450 wouldn't be the choice, but here we're only using
it as a .65 V reference with some gain.

kilowattski · 27th October 2004, 03:24 AM

Thank you all for your replies. It is as I thought. Goodnight everyone.

EUVL · 27th October 2004, 05:30 AM

> but here we're only using it as a .65 V reference with some gain

Nelson,

Since we are on the topic, how important is it to match hfe and Vbe ?

Can we have too much gain, or the higher the hfe, the better ?

Thanks,
Patrick

yldouright · 29th October 2004, 03:28 PM

kilowattski

Where on Long Island are you? I have a thread open looking for NYC area build partners and would be interested in talking to you about it. Just click on my name and pop me an email.

26th October 2004, 08:00 PM	#1
kilowattski diyAudio Member Join Date: Aug 2003 Location: Long Island, New York	ZTX450 for AX I have been through this myself already. I can see any reason why I can't use the ZTX450 instead of the MPSA18 or BC550C in an Aleph X? Can anyone confirm this in case I may have missed some obscure reason. __________________ ----------------------------------------------- Kilowattski

26th October 2004, 08:38 PM	#4
EUVL diyAudio Member Join Date: Oct 2003	ZTX450 I am only quoting datasheet : Tr Type Noise Figures Data Source BC550 4dB Philips '99 MPSA18 1.5dB Fairchild '97 ZTX450 not quoted Zetex Patrick

27th October 2004, 03:24 AM	#6
kilowattski diyAudio Member Join Date: Aug 2003 Location: Long Island, New York	Thank you all for your replies. It is as I thought. Goodnight everyone. __________________ ----------------------------------------------- Kilowattski

27th October 2004, 05:30 AM	#7
EUVL diyAudio Member Join Date: Oct 2003	hfe abd Vbe > but here we're only using it as a .65 V reference with some gain Nelson, Since we are on the topic, how important is it to match hfe and Vbe ? Can we have too much gain, or the higher the hfe, the better ? Thanks, Patrick

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26th October 2004, 08:26 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	No reason at all, at least not in this application.

26th October 2004, 08:30 PM	#3
Netlist diyAudio Moderator Join Date: Jan 2003	MPSA18: NF-ra,45V, 0,2A, 0,625W, 160MHz, B>500 BC550: Uni,ra,50V, 0,1A, 0,5W, 300MHz ZTX450: Uni, 60V, 1A, 1W, >150MHz The MPSA18 and BC550 are both low noice (ra) and if you take the BC550C they both have a high Hfe. My guess is that all should work properly. /Hugo Oops, too slow for Nelson

26th October 2004, 09:26 PM	#5
Nelson Pass The one and only Join Date: Mar 2001	No question if this were an input stage device that the ZTX450 wouldn't be the choice, but here we're only using it as a .65 V reference with some gain.

29th October 2004, 03:28 PM	#8
yldouright diyAudio Member Join Date: Aug 2002 Location: New York, NY	kilowattski Where on Long Island are you? I have a thread open looking for NYC area build partners and would be interested in talking to you about it. Just click on my name and pop me an email.

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