small transistors for above >100 Mhz

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Hai All

 

I'm looking some information and the kind of small transistors(TO-92) type like BC547/1904/2222 that work's above 100Mhz.

Did someone had experience with small cheap transistors for > 100 Mhz work ?

 

Thank you 

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Last Edited: Wed. Apr 27, 2022 - 10:50 AM
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Jeckson wrote:

I'm looking some information and the kind of small transistors(TO-92) type like BC547/1904/2222 that work's above 100Mhz.

 

How well do you want them to work above 100MHz?

 

What fT do you need? GBW? Turn-On/Turn-Off time?

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

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Jeckson wrote:
above 100Mhz

 

EU marking is BFnnn.

 

Edit: Google suggests BF259, BF494, BF198, BF422, BF423, and BF245

(first one is High voltage)

Ebay cheapest TO92 (100pcs) will be BF199 and BF494, and they have also SOT23 types.

 

 

Last Edited: Mon. Apr 25, 2022 - 12:23 PM
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Jeckson wrote:
(TO-92)
SMT at onsemi

RF Transistors (onsemi, fT >= 400 MHz)

General Purpose and Low VCE(sat) Transistors (onsemi)

 

"Dare to be naïve." - Buckminster Fuller

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grohote wrote:

EU marking is BFnnn.

 

Edit: Google suggests BF259, BF494, BF198, BF422, BF423, and BF245

(first one is High voltage)

Ebay cheapest TO92 (100pcs) will be BF199 and BF494, and they have also SOT23 types.

yes

 

gchapman wrote:
SMT at onsemi

 

RF Transistors (onsemi, fT >= 400 MHz)

General Purpose and Low VCE(sat) Transistors (onsemi)

 yes

 

The above transistor like BC547/N9406/N2222/N4401 only at 100 Mhz in Lab tested.The info's(Characteristic of Transistor) above > 100-200 Mhz didn't tested.Since I didn't had equipments to test it.

 

Any addtional info will be appreciated.

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You still haven't said what you want to do with them.

 

An RF transistor, for linear amplification,  is a very different beast to a high-speed switching transistor.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

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Brian Fairchild wrote:
is a very different beast

 

Linear types are very happy with a signal of 1 microvolt. Some of them are declared as "ultra low noise",  fT goes to 4GHz, for example bfw92.

 

 

 

 

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Brian Fairchild wrote:
An RF transistor, for linear amplification,  is a very different beast to a high-speed switching transistor.

 

Look at this meet the criteria:

 

https://id.aliexpress.com/item/1...

 

Any info's will be appreciated.

 

 

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Jeckson wrote:
Any info's will be appreciated.

 

Transistor BF494 is a 'working horse' among BF species. One among 6 types I offered to be seriously considered. One among cheapest in Ebay.

 

It is suitable for RF amplifiers and oscillators.

 

What other info you need? Will you tell us why you ask, please.

 

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grohote wrote:

 

What other info you need? Will you tell us why you ask, please.

 

Thank’s,Will look at the data sheet.

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grohote wrote:

It is suitable for RF amplifiers and oscillators.

 

In other words...linear application, not switching.

 

It has a relatively low fT of 120Mhz, a low DC gain of around 65, and a maximum collector current of 30mA, and a low Vce (max) of 20V.

 

Ideal for battery powered MF/HF band radios (which is what it was designed for) but not much else.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

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Brian Fairchild wrote:
Ideal for battery powered

 

True. If you search for BF494, you will find that the net space is infested with various /but similar/ types of 1, 2 and 3 transistors FM transmitter where '494 is for oscillator.

Something any mother will like for monitoring a baby.

Main applications are both RX and TX RF-design (around 30Mhz), where BF494 is superior to other transistors. Seems that TO92 does not go over 150M, guess.

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grohote wrote:
Seems that TO92 does not go over 150M, guess.
Apparently so.

2N3904T: 200 mA, 40 V NPN General Purpose Bipolar Junction Transistor (onsemi)

... and to 100 MHz as an amplifier.

[data sheet]

[fT >= 300 MHz]

 

"Dare to be naïve." - Buckminster Fuller

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Transistor 2N3904 is general-purpose NPN capable to switch very fast... but, for the small RF signal, it is worthless.

 

All BF types are with just moderate hfe. No chance for 100, or more that 2N3904 does have...

 

Remember a discussion: which transistor is best for a "super audion" (or, was it "ultra audion"). The winner was one of 2N43xx, do not remember which- the secret is in a tiny base current and B-C isolation.

 

Example of audion, here is our BF494.

 

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grohote wrote:
The winner was one of 2N43xx
I sometimes used it.Will look at datasheet also.

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I found FCS type transistors and cheap.

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Google offer FCS9012/13/14/18. Which was your choice? Seems that you are up to power (not RF) transistor.

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grohote wrote:
Google offer FCS9012/13/14/18.
 ???

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Google offer FCS9012/13/14/18. Start writing 'transistor fcs' and Google will offer what you may like it, or you will search for more:

 

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FCS substitutes of N and SC types.Looks like Chinese manufacture.

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