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Old 26th March 2013, 04:03 PM   #1
AMV8 is offline AMV8  United Kingdom
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Default Where can I buy BF422, BF423

Hi
Where can I buy BF422 BF423?

I am trying to buy BF422 but Mouser just stopped selling them. They used to be 200 for 20. However they are no longer available at Mouser and they do not plan to restock. BF423 are also getting scarce.

The specs for BF422/423 are;
Vdc 250
Ima 50
mW 600/800
MHz 60
gain 50
Cpf 2.8/1.6

BF421/423 are the same except 300Vdc however these have not been around for some time.
Don
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Old 26th March 2013, 05:26 PM   #2
mjselan is offline mjselan  Slovenia
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Default Maybe KSP44 and KSP94

Maybe KSP44 and KSP94 may be of some use to you? Mouser has them in stock.
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Old 26th March 2013, 05:49 PM   #3
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Cricklewood Electronics - CCTV. CCTV Equipment. CCTV Systems. Digital CCTV Cameras

or

BF422
BF423

Last edited by KatieandDad; 26th March 2013 at 05:52 PM.
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Old 26th March 2013, 06:18 PM   #4
AMV8 is offline AMV8  United Kingdom
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Hi
Thanks for the replies

Mjselan Thanks; these look nice parts, however I am hoping to find some semiconductors with a lower capacitance. In the BF422 and BF423 the capacitance is 1.6 / 2.6 pf as against 7pf in most of the possible replacements I have seen todate.

Katie and dad Yes both of these sources do sell the parts. However the price at other companies has always been around 0.07 per part as against 1.25 and 0.25 at the companies you mention. Those sounces are OK if you only want 1 or 2 for replacements but the prices are not realistic for orders of more than 1 or 2.

Don
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Old 26th March 2013, 06:30 PM   #5
Ketje is offline Ketje  Belgium
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Perhaps this one?
Transistoren - BF serie - BF421 - EOO - ElectronicaOnderdelenOnline
Mona
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Old 26th March 2013, 06:39 PM   #6
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Sorry, I thought you only wanted one or two to repair something sentimental.
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Old 26th March 2013, 07:38 PM   #7
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Do you really need the 250V breakdown?

The KSA916/KSC2316 may be suitable substitutes.

Be careful when comparing capacitance specs from Data Sheets. The values vary over a WIDE range depending on test conditions (i.e., the amount of reverse bias on the PN junction). A manufacturer who publishes a spec based on a modest reverse bias of 5 or 10 volts may show a worse value than a manufacturer who measures with 50 or 100 volts - even though the "worse" part is actually faster!

Dale
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Old 28th March 2013, 06:14 AM   #8
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AFAIK, BF420..423 are current production parts from NXP China and widely available. The Toshiba counterparts are a bit scarcer. You can look for BF821 if SOT23 works for you.
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Old 17th April 2013, 03:19 PM   #9
AMV8 is offline AMV8  United Kingdom
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Thanks for thr replies. I did manage to find some BF422 from Toshiba but I believe I may have got the last ones around.

Ketje
Thanks for your suggestions. I tried the company you suggested. He had just sold out the week before and his friends had also sold out the week before.

D Chisholm
You may well be correct that the capacitance figures are not what they seem with some transistors. However I always try to buy transistors with the most linear transfer curves and lowest capacitance. The audio equipment I have built seems better when I stick to that position - and some makers do claim that their parts were designed to have low capacitance.

linuxguru
Thanks for your help although I do have all the parts I need now.

Thanks for thr help
Don
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