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Author Topic: 2N2222A TO-18 vs TO-92  (Read 877 times)

KX4OM

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Re: 2N2222A TO-18 vs TO-92
« Reply #15 on: June 03, 2021, 06:29:17 PM »

Mouser has the Microchip 2N2222A in stock. $2.28 single lot. I put several in my cart, along with some other stuff.

Ted, KX4OM
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AC2EU

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Re: 2N2222A TO-18 vs TO-92
« Reply #16 on: June 05, 2021, 12:42:15 PM »

I would also suggest you buy your semi's from mouser, Newark, digikey, etc, or some legitimate product line seller.

I just got burned by a Ebay seller who claimed to be selling Toshiba 2SC1678 HF transistors. They turned out to be counterfeit junk where the gain dropped off after 7 MHZ.
The Real ones go all the the way to 30 MHZ.

After contacting him, he immediately "cancelled" the order and refunded my money ( I don't know how that works since I had the transistors!).
I suspect it is way to avoid negative feedback when he gets caught? I say this because I proved to him they were fakes in a couple of ways, yet he is still selling the same junk even though he feigned surprise.

The transistors didn't look right, but i tried them anyway. So it was a slight waste of my time in the end.

KM1H

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Re: 2N2222A TO-18 vs TO-92
« Reply #17 on: June 05, 2021, 01:21:02 PM »

Quote
I just got burned by a Ebay seller who claimed to be selling Toshiba 2SC1678 HF transistors. They turned out to be counterfeit junk where the gain dropped off after 7 MHZ.
The Real ones go all the the way to 30 MHZ.

Publish his Ebay ID to help warn others.
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AC2EU

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Re: 2N2222A TO-18 vs TO-92
« Reply #18 on: June 05, 2021, 06:00:43 PM »

Quote
I just got burned by a Ebay seller who claimed to be selling Toshiba 2SC1678 HF transistors. They turned out to be counterfeit junk where the gain dropped off after 7 MHZ.
The Real ones go all the the way to 30 MHZ.

Publish his Ebay ID to help warn others.

Activeparts
Interestingly, he has pretty good feedback, but he may be maintaining it by the cancellation method I described.
However, there were two negatives on there about "useless counterfeit transistors" and "factory rejects" on other types.
SO, it's not the first complaint he's had about  it.

When I complained to him, he said I was the only one who said the 2SC1678s were no good.
That didn't ring true to me.
Most of the radios that use these are CB transmitters.  They would be getting 0.5 watts instead of 5 watts!

N7EKU

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Re: 2N2222A TO-18 vs TO-92
« Reply #19 on: June 05, 2021, 06:47:30 PM »

There's a few ways you can spot fakes,

One is that most of these transistors haven't been made for many many years. So after that much time, even if stored in pretty careful conditions they will still look tarnished and a bit old. So all these ads showing nice shiny new parts are obviously fake.

Another way is to look carefully at the original data sheets. The outline drawing will often show specific shapes of the case and lead; the counterfeit ones will not have these details.

73
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Mark -- N7EKU/VE3

KM1H

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Re: 2N2222A TO-18 vs TO-92
« Reply #20 on: June 06, 2021, 03:19:13 PM »

I have scores of NIB transistors going back to the 60's that still look as if they were made last week.

Here is a USA seller, not Fleabay, at only $1.25
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KB1GMX

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Re: 2N2222A TO-18 vs TO-92
« Reply #21 on: June 06, 2021, 03:41:39 PM »

The 2n2222 TO18 is a performance up grade with a few other changes
to make the ubitx work somewhat better on 20M and up.

Over the years doing RF work I've found the roach (2n2222 is a very
old design early 60's)  to be a far better part than the 2n3940 at higher
power.  The pn or 2n prefix 2222 parts in plastic handle half the power
and with a lot of testing most are no better than 2n3904 and some
much worse.   In designs I do and work with the plastic phoney 2n2222
is never used as its an inferior wider spread part.

Dissipation is generally not that great an issue in ubitx as they are
used in pairs as in 2 for the predriver, 4 for the push pull driver to
get .5W to push IRF510s to 10W (hopefully).

FYI if not modified the V3 version due to layout of the LPF
relays has terrible blow by and as a result high harmonic
content at the antenna.  Due to other issue it produces a
spur(s) out of band when used above 20mhz.

I am well acquainted with that beast.

Allison
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KM1H

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Re: 2N2222A TO-18 vs TO-92
« Reply #22 on: June 07, 2021, 11:36:28 AM »

Quote
Over the years doing RF work I've found the roach (2n2222 is a very
old design early 60's)  to be a far better part than the 2n3940 at higher
power.  The pn or 2n prefix 2222 parts in plastic handle half the power
and with a lot of testing most are no better than 2n3904 and some
much worse.   In designs I do and work with the plastic phoney 2n2222
is never used as its an inferior wider spread part.

AFIK the 2N706 was the 60's predecessor to the 2N2222. I still keep a few on hand for products from that era I service.

Carl
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AC9QC

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Re: 2N2222A TO-18 vs TO-92
« Reply #23 on: June 29, 2021, 12:07:02 PM »

Any of you ever use NTE278 for the 2N5109s? Is it gtg as a sub?
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N7EKU

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Re: 2N2222A TO-18 vs TO-92
« Reply #24 on: June 29, 2021, 01:23:52 PM »

Hi,

They are made as direct substitutes I think so they should be good as long as they are genuine.  If you are still looking for real 2n5109's, shoot me a private message as I have some I can sell you at a decent price.

73,


Mark
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Mark -- N7EKU/VE3

AC9QC

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Re: 2N2222A TO-18 vs TO-92
« Reply #25 on: June 29, 2021, 02:10:45 PM »

Hi,

They are made as direct substitutes I think so they should be good as long as they are genuine.  If you are still looking for real 2n5109's, shoot me a private message as I have some I can sell you at a decent price.

73,


Mark

Thanks for the offer, I'm going to keep that in mind as a fall back and may buy the 278s. Just wasn't sure if they were great, some subs are not quite as precise as others if you get my drift.
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KB1GMX

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Re: 2N2222A TO-18 vs TO-92
« Reply #26 on: June 30, 2021, 07:15:33 AM »

KM1H,

I have a bin of 2N706 and 2N708 from a company I worked for back in the early 70s.
Good part still using them. Another oldie but good was the 2N2219, basically 2n2222(a)
in the larger TO5 can.

And yes, they are still bright and shiny.

Also the 2N5109 is a old device as well.

The 2N3904 is not a bad part but its not the same as the 2n2222 for gain vs current.

Allison
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K6BSU

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Re: 2N2222A TO-18 vs TO-92
« Reply #27 on: June 30, 2021, 09:55:49 AM »

Any time I use the TO-92 version of the 2N2222 I look up the data from that particular manufacturer.  There are two versions of pin-out. 
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G0HZU

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Re: 2N2222A TO-18 vs TO-92
« Reply #28 on: July 04, 2021, 07:21:29 AM »

One other thing to watch out for when swapping between BJT parts is differences in instability. A few years ago I measured the s-parameters of quite a few common small signal BJTs at various DC operating points on my VNA. The VNA can output a 2 port s-parameter data model of the BJT at up to  several GHz. The model can then be imported into and analysed on a PC using a linear RF simulator. The results were quite revealing and show that these devices can potentially go unstable and oscillate up at UHF if the circuit layout permits.

The VNA model of the 2N3904 predicted it can oscillate at over 800MHz. I recall the BC547B could manage about 600MHz and it predicted the MPSH10/MMBTH10 can oscillate way up at 1800MHz. I haven't measured a 2N2222A but I'd expect it to be able to oscillate at at least 400MHz but a lot depends on the DC operating point and circuit layout in each case.

« Last Edit: July 04, 2021, 07:23:59 AM by G0HZU »
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Regards
Jeremy

KM1H

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Re: 2N2222A TO-18 vs TO-92
« Reply #29 on: July 04, 2021, 06:29:07 PM »

Quote
The results were quite revealing and show that these devices can potentially go unstable and oscillate up at UHF if the circuit layout permits.

Which was why most circuits used a small ferrite bead or three on a very short base lead.

Quote
The 2N3904 is not a bad part but its not the same as the 2n2222 for gain vs current.

Use a pair of closely matched of any small signal device and even some bigger RF devices for more power.

Carl
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