G'day everyone!

The other day I dug out my great grandfathers old National radio he brought back from japan decades ago to try and see if it works. unfortunately when I connected 4.5V from the bench power supply it just crackled and tuned into nothing whatsoever. I started with the easy suspects like dirty volume etc but with to avail. I ended up finding the problem when I busted out the can of HFC and froze some transistors. turned out the converter transistor had been replaced with a AF126 which had gone bad. by bad I mean there is a 1.0V drop from Emitter to Collector with the multi-meter on diode check and ~250mV from Collector to Base with a ~800mV drop when the leads are switched. clearly not a happy camper. so I searched for sometime until I found the service manual on the Kevin chant website here:

https://www.kevinchant.com/uploads/7/1/0/8/7108231/r-357.pdf

after inspecting the schematic I found what the original converter transistor was supposed to be which is a 2SA341. so it was time to do some Ebay hunting only to discover a NOS 2SA341 is about $14! I'm not paying that much for an old Panasonic transistor! anyway I went off to think about this for a while and came back with the idea of getting NOS Soviet transistors and after finding a suitable replacement I bought a bag of 25x GT309 transistors for about a dollarie-doo each. few weeks later I got the little pouch of transistors and popped one into the radio and to my surprise it works perfectly!

I've tried to get the link to Brad's email to upload photos but I'm getting a 404 error for some reason

Anyway what do you guys (and girls) think about using soviet transistors as replacements?

I have a large stock of Soviet germanium transistors which I brought when I found things like OC44’s etc were either hard to get or ridiculously expensive.
Have used lots of Soviet replacements in my early transistor radio restorations and have found that they are excellent.
I think from memory I have about 4 types and they cover about every situation.
JJ

G’day Johnny
What types have you collected? I’ve bought MP20A’s and MP40’s as well. Not just the GT309’s. very good prices and lots of them to buy!

Some Russian stuff is interesting and often the bad reputation is sometimes all talk.
Years ago when I was in Eastern Europe I saw my first Lada niva 4x4 and I liked it.
Then when I came back to Oz they were being sold here and so I bought one .
I did a few mods to it and then did a trip around Australia in it.
It was great! I remember one day in NT I crossed 6 rivers in one day .
It was a great car and the motor use to be Italian. Then the Russians built them.
One thing I did hate was the seats!
Pete

Did you know you can use BC557s to replace just about any PNP germanium transistor in a transistor radio?

Never found one yet that didn't work. Usually makes the radio quite lively too, more sensitive, but I've never had a stability problem doing this.
Did a few UK radios some years back, replacing those OC169 / OC170 / AF117s which have a high mortality rate.

Only caveat, you'll need to adjust the bias up a tad if you want to use them in the output stage, for obvious reasons. Elsewhere in the radio they will happily self-bias and compensate for the 0.4v Vbe difference. Modern silicon transistors are so much closer to a perfect transistor that they just have to work! Even a humble general purpose "audio" transistor like the BC557 has a higher Ft than the early germanium "RF" transistors.

Hey Pete
I’d never heard of a Lada Niva until now and looking on car sales their not expensive either. Quite an interesting car

Hello again Ian
I mean I completely see where your coming from and silicon transistors don’t grow whiskers and (generally) don’t go noisy and just last a whole lot longer in extreme weather conditions but it’s just not as fun as testing a bunch of different germaniums for the best gain and leakage current for the purpose. I think personally if a electronic device is designed for germanium (or Geronimo’s as I call them) it should be kept germanium.

Does anyone know Brads email so I can upload pics?

Just send it to admin contact.
I can't post the email,Brad would turn green if I did that haha .
The link is there to contact him.
Pete

Hmmmm. Germaniums...

Philips MT3. The original Class A OC72 output stage goes into thermal runaway if you use a new battery pack, unless the room temperature is less than 20 degrees C. They all do it.

A BC327 drops straight in and solves the problem, without needing the heat sink or any other modification. Come to think of it, the BC327 is overkill, the BC557 is well within its ratings for the job.

Do you use paper capacitors or carbon composition resistors in a restoration ? Of course not, you replace them with much better modern parts that will not fail again in the future. IMHO, same goes for germanium transistors.

Ah yes thank you Pete. I’ll send the pictures in tomorrow as I don’t have them on my phone.
Pete do you still have your Lada Niva? I’m curious about the longevity of such cars although I know this isn’t the place to talk about them.

No a wall fell on it!
Like many Russian items the quality depends on what was available during manufacture and which factory.
Mine was a 1990 model so that's a long time ago now and the ones that are still around would be trouble by now.
The most important thing is to change the oils and I changed all oils every 5k because I drove around Australia in it pulling my camp trailer for over a year. ..it was a great car and it provided a cheap way of going around Australia.
I travelled a lot in my 20 years ,both here and over seas.now I don't go anywhere!. But to answer your questions,no I would not buy one now unless it was to be a hobby car...... they are pretty old now
Pete

I am seeing quite a few Germanium mixer Oscillator transistors failing.

On Russian: I note they ruggedised 5Y3 & it looks more like a 6X4 in construction style. It has a massive filament & it looks like it has a cathode sleeve as it behaves like a heater rectifier.

I believe one reason that helped get them to Berlin first, related to them having some deal with Carl Zeiss. So had access to the best lens technology at he time & took a lot of it to Russia. Some of this was obviously used to create "night vison" which would have been one hell of an advantage in getting to Berlin, & spotting Germans and their hot objects.

I have a pair of Soviet era Binoculars. They must have used that technology on them. When I bought them, I looked down a street at a bridge and the signs on it, around a mile away, with a good quality Japanese pair. Fine: I bought the Russian ones as I could read the signs with them.

Marcc, I have a pair too.
Had them for years and years.
I like them , actually I like Russian stuff.
Don't know about their TV's though haha

A wall fell on it? I don’t know if I want to ask!

Ian I wouldn’t compare the shelf life of a germanium to paper caps or carbon resistors as paper naturally breaks down to air and carbon resistors can drift over time but germanium transistors can last as long as silicon even though they have much wider tolerances from the factory and are temperature sensitive. It really just depends on how their being used. Other than whiskers a germanium transistor sitting unused has no reason to fail.

Marcc do you know the model number/manufacturer of these Russian binoculars? Sounds quite interesting to look into

What they call a sediment crack in double brick walls, it's from the clay gound contracting, the garage wall fell on it.
No insurance

Lada sold cars here in the early 1990s but the plan was short-lived. They typically fell apart when hitting Australian pot holes. East German Trabants were better engineered.