[morzh]

Brenda



You are talking of RoHS whiskering problem due to tin solder having no lead and hence whiskers problem which is a well known phenomenon. What does it have to do with Ge transistors?

[BrendaAnnD]

http://www.vintage-radio.net/forum/showt...hp?t=35171

Check out some of the pics. Pretty cool looking.

[BrendaAnnD]

http://www.vintage-radio.net/forum/showt...t=whiskers

[morzh]

So they were using tin in them. Tin does whisker if not mixed with other metals. They used it in these transistors.


Cool looking, yes. But it does not really say anything bad about Ge in transistors.

The problem was, they at the time (the Ge were the first transistors in use) used tin to plate the walls of the can. And the whiskers grow from them. But not from Ge crystal. Same would happen to early Si transistors should they be in the same cans.

But they were a later technology and fewer of them ended up in tinned cans and more got molded plastic casings.
Also not all Ge transistors are in such cans.

Since they are very popular in Russia with amateurs today (and this is way more widespread hobby there than it is here) I went to look for any evidence of problems with old stock.....I failed to find any....and the size of that stock is huge.

Again, maybe they did not use tin plating there.....though I think they might. I remember opening a few, they looked like copper (the cut was red) plated with something that could be tin, or tin-led.

Again, Ge has nothing to do with it.


PS. Just went to look for info in English.
Seems like this problem plagued AF11x (114, 117) tin-plated series of Ge transistors.

[Ron Ramirez]

So, Morzh (Mike)...if any of my 1960s Fisher or Harman Kardon receivers need any Ge transistors, are you saying I can get anything I want from some source in Russia? Can you give me the web address of a reliable supplier?

[morzh]

Ebay has plenty.

http://www.ebay.com/itm/10x-MP10B-Russia...3cd8465571

MP10 is an NPN.

http://www.ebay.com/itm/5-X-MP41A-2N2428...1e83f61efa

MP41 is PNP.

However when (and if) you need it, I could find out for you from the Russian forum if I could get a larger cheaper shipping from them, though I do not believe you will need many.

Also again, when (and if) you need any we will first see what those are (voltage/frequency/beta) and then I have a Soviet catalog from 80s at home, we will find out the closest substitute and then will try to procure it.

Another option is - there are authentic local transistors also sold on eBay, many-many Ge transistors of all kinds, even the tophat-pinch tops.

[Mondial]

A lot of times you can replace the Ge transistors with modern silicon PNP's if you take into account the different Vbe for biasing. Sometimes it's a drop in replacement. A common audio silicon like a 2N5087 usually has better freq response (Ft cutoff freq) than most early Ge RF transistors, and lower noise in addition.

Motorola did a lot of this type substitution in its two-way radio designs from the 60's when they continued to manufacture them into the 70's.

[morzh]

http://www.ebay.com/itm/5-X-P416A-2N2089...1e82a8b7c1

This is P416А, a Hi-frequency (60MHz) transistor I used in radios. This is probably the most popular type.

Same

http://www.ebay.com/itm/big-lot-P416A-B-...2ecdc4e08e

As you can see even with shipping they are not that expensive.

[Ron Ramirez]

Very interesting. (where's Arte Johnson now when I don't need him...)

Of the receivers I have so far (Fisher 170, Fisher 220-T, Harman Kardon SR600, Marantz 2215B, Toshiba SA-735), the Harman Kardon SR600 is the only one that *might* need something. I'll know more when I get around to digging into it. It uses Ge transistors, being one of H-K's first all-transistor receivers (1964). The Fisher 220-T and Marantz 2215B work well; the Fisher 170 tries to work but has distortion in the left channel; and the Toshiba is dead. I'm almost positive the 170 is new enough to use silicon (1973), and I'm sure the Toshiba is also (it's from 1978-1980).

[BrendaAnnD]

Speaking of buying things from the former eastern bloc, why is it that I can buy something from Ukraine or Latvia or Lithuania and get way cheaper shipping costs (and pretty reliably fast, too, considering they have to go to the states before coming here to me) than I get from anywhere in the states except for CA?

[Phlogiston]

I don't know about Russia (we have Russian friends here), but, I am sure that some of the transistors sold out of China are not only counterfeits, but very inadequate ones at that. There is a lot on the web about this. I have experienced it myself. Very much worse than Chinese tubes or caps.

If a output transistor is obsolete, but you find someone in China that just happens to have some. Find a good substitute and get it from Mouser.

[Ron Ramirez]

We were talking about Russia, not China...Acked re: quality (or lack thereof) of Chinese semiconductors...

[morzh]

Well, not to dispute the fact that US semiconductor industry was alway way ahead of the Soviet one, and I would take an American transistor over a Soviert one any time of the day, but the Soviet transistors (and what I am sure of is there are no counterfeits there) as I remember them, at least the small signal ones, were reliable and fully compliant with their respective datasheets.

To answer Brenda's question, Brenda, in Ukrain and im most of Russia the standard of living is still quite a bit lower (forget Moscow, Moscow is no longer Russia really) than it is here, hence the prices.

[Arran]

In relation to what Mike (Morzh) was speaking of the instability I am speaking of is unrelated to tin whiskers, tin whiskers cause shorted elements not intermittent ones. The transistor linked to was also a European made Phillips type, those obviously used tin plating in the cases, at least in that production of OC171s. As Mike suggested had they used a copper or some other plating, or mixed lead in with the tin plate, they would not have had this problem, it also has nothing to do with what material they chose for the elements.
I think that is the Soviet made Germanium transistors were made to military specs, which they most likely were, they likely would have used something other then tin plate in the cases. I think that the noise and intermittent problems with older transistors are due to a combination of age and early production methods, germanium transistors were largely phased out in new equipment by the late 60s here. Since the Soviet Union obviously stuck with germanium longer then they did in the West they likely would have refined out most of the bugs with experience.
Tin whiskers are not unique to early transistors though, much of that newer, "politically correct", lead free junk solder is notorious for forming tin whiskers, not to mention cracking and cold solder (dry) joints. In fact they are not allowed to use lead free solder in medical, aerospace, or military equipment, even in Europe, for those reasons. Tin plating will also create whiskers on a piece of sheet metal, often with no voltage potential across it at all: http://www.youtube.com/watch?v=apnlJJ0t_LY
He says he has even found tin whiskers like this in NOS TVs, new in the box.
Whatever the cause, the problem is the same, if you have a defective transistor you will need to find some form of substitute.

P.S I think that a lot of the shipping costs are baloney, like for example it costs at least 30% more to ship something from Australia to New Zealand then it does from New Zealand to Australia, why? Both are out in the South Pacific, similar culturally, similar standards of living, it just illustrates how arbitrary a lot of postal rates are.
Regards
Arran

[Ron Ramirez]

Well, allow me to ask this question and (slightly) change the subject.

In SS equipment, what type of electrolytics would you recommend? Panasonic, Nichicon or ?? Which is better, high temperature or low ESR?

When you haven't dealt with repairing SS equipment on a component level in decades, you tend to forget these things...