ZTX450 for AX

[kilowattski]

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]

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

 

[Netlist]

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]

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

 

[Nelson Pass]

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]

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

 

[EUVL]

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

 

[yldouright]

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.