Transistor 2N2084

[Oldelectronics]

I have some 2N2084 transistors I have seen some sold as 2N2084 JAN transistor and a separate add with 2N2084 USA transistor. I take it the JAN is for Japan and is just a country of manufacture the components being electronically identical? Just curious!!

Kev

[Herald1360]

ISTR JAN is for Joint Army Navy ie Mil-Spec. Nothing to do with Japan!

So same electrical spec but possibly better quality or at least guaranteed specs.

[Oldelectronics]

Thank you Chris much appreciated the USA made me think it may be country of origin (a doh moment)! That would explain the price difference 99p each for JAN, 99p for two of the USA ones.

Thanks once more.

Kev

[paulsherwin]

Yes, it's a longstanding US military standards body. It was common for JAN valves to have their own codes like the British CV system, but transistors normally use the civilian code but with JAN approval. It's more likely to refer to encapsulation or temperature standards rather than anything electronic.

[Argus25]

You can nearly always be sure with a mil spec part that you have a very high quality item. For this reason I try to buy JAN and JANTX transistors for my projects.

The 2N2084 is an absolutely terrific RF transistor, high gain and low noise. They rival or beat any similar type and they are a ideal replacement for whisker affected AF11X transistors. They also look good in sets on the PCB's and the long leads are helpful. All of the AF11x devices in my Hacker radio were replaced with 2N2084's.
I've attached a photo I posted on another thread.

[Oldelectronics]

Hi Argus I bought some Tesla OC169s having read the thread you posted on, and they have been brilliant and I am looking forward to trying the 2N2084s you mentioned. I have run out of room for woody's so have been looking at transistor sets settling on Hackers and have replaced the AF117s in a Herald and a Autocrat with Tesla OC169s A bit dear but worth it for keepers. Out of interest do you have a pin out for a 2N2084?

Regards, Kev.

[Skywave]

Originally Posted by Oldelectronics

Out of interest do you have a pin-out for a 2N2084?

http://www.semicon-data.com/transist...2n/2N2084.html

Al.

[Argus25]

Originally Posted by Oldelectronics

Hi Argus I bought some Tesla OC169s having read the thread you posted on, and they have been brilliant

Kev, Those Tesla OC169's are rather lovely. The fellow who sells them also has a really nice transistor hfe tester and he tests them before sending them out. I used those transistors in my Eddystone EC-10 radios. Being resin filled I highly doubt if these OC169's would ever fail.

The problem with the originals (and the whisker issue) is that they could fail any time. Many years ago I had fixed a few by ablating the whiskers with a low voltage power source, but after I did that, the problem returned after a few years as the whiskers grew back. My brother went as far as washing out the whiskers & replacing the grease in some of them. But I suspect whatever the fix, ultimately they will grow back although it might be possible to replace the grease with resin.

At least with the AF11x series there are a few replacement options.The AF118 is a difficult customer. It was used as a video output transistor and has high voltage ratings. The 2SA358 is the best drop in replacement I could find. Luckily the Japanese made a few germanium video output transistors.

[Oldelectronics]

Thank you Al for the pin out much appreciated.

Hi Argus someone had tried to fix the Herald I bought from a local antique centre by cutting the screen lead on the AF117s which may not have worked or stopped working again. Those Tesla ones are now gone they seem to have been going like hot cakes! So I would like to give the 2N2084's a try as well as being much cheaper they seem to be available. The ones I have seen are gold colored though not silver. I don't suppose it matters.

Kev

[Argus25]

Originally Posted by Oldelectronics

Those Tesla ones are now gone they seem to have been going like hot cakes!

Yes, I figured that would happen. About a year ago I bought a good number of them from him for future repairs. I had not seen these anywhere else, they are unique, so I figured once they were gone they would be unobtainium.

[paulsherwin]

Just a reminder that replacing AF11x transistors with substitutes is a lot easier than is often assumed. The transistors being discussed in this thread will be fine, but so will many others - any 1960s Ge RF transistor is likely to work. The selection is largely down to availability and price, with cosmetic appearance a factor for some people. The Russian types are often used because they are plentiful - the USSR switched to silicon planar technology about a decade later than the west so there are still lots of stocks around.

[Oldelectronics]

The nice thing about the ones discussed Paul is the decent lead length as some with short leads are a bit of a fiddle! I suppose I must be more adventuress and try some others?

Kev

[paulsherwin]

I've found I've generally just acquired Ge RF transistors over the years from various sources, so haven't needed to buy many. Nowadays the Russian ones are the most cost effective NOS transistors to buy, so if I didn't have anything suitable I'd probably invest in 20 or 30 of those. 2N2084s aren't too pricey though.

Don't forget that jellybean PNP Si transistors like 2N3906s or BC558s will usually work without any circuit changes, though they obviously look out of period if appearance is important, and as you say the shorter leads can be a nuisance.

[Argus25]

Originally Posted by Oldelectronics

The nice thing about the ones discussed Paul is the decent lead length as some with short leads are a bit of a fiddle! I suppose I must be more adventuress and try some others?

Kev,
When I started searching for AF11x replacements, I realized the application was important. While poorer performing transistors could be got away with readily in plain MW radios, the noise & gain performance was more important, say if they were used in comms radios like the EC-10. So I designed a high frequency test jig to evaluate the transistor performance at 30MHz (about as high as the EC--10 radio goes).

It was during these tests that I noticed the outstanding performance of the AF178. Its better than the AF179 for example, though theoretically there shouldn't be much difference. I acquired AF178's and graded them for gain at 30MHz. I prepared a batch of them for later use with colored dots to identify the gain and also I varnished them with marine varnish so they won't get a corroded look in the future.

For my own home brew radios I always fit these transistors to sockets. I got mil spec sockets with gold plated pins. If these can be used it is preferable as then the transistor leads don't have to be heated with the soldering iron. (germanium transistors are more sensitive than in this respect than silicon).

If the Tesla OC169's and the 2N2084's can't be acquired, the AF178 is wonderful, but sometimes it needs its leads extended and sleeved to replace AF11x. Last time I looked Langrex had AF178's.

[paulsherwin]

AF178s are available from several eBay sellers in the UK and Europe, and while the postage is a little high they're not especially expensive as Ge RF transistors go. The lead length seems to vary.

[Oldelectronics]

Thanks for that Argus.Not having the technical skills or equipment of many of you guys on here these alternative are a real help.

Kev