Germanium investigations

[OldDIY]

NTE105, Транзистор: PNP; биполярный; германиевый; 40В; 15А; 150Вт; TO36 | купить в розницу и оптом

 

[Soundhappy]

Does MR need GE's?

I will happily send some.

Hope Diyers get updates in the future

 

[Soundhappy]

just measured 0.141% distortion at -10dB level
not bad
I can see second harmonic ~-60dB, and third ~ -80 to -90dB, depending on the current I set with trimmers
....and hf rollof is still there
but it sounds awesome

done!
this is when cranked up at 20volts with LM317 regulator
distortion dropped to 0.076%, intermodulation at 0.101%
I will build another version, with bigger heatsinks

Congratulations Any news about your Ge amp ?

 

[codyt]

Hope Diyers get updates in the future

What video are those screen captures from? Not sure I’ve seen that one

 

[MisterCornwall]

It’s part of the Steve Gutenberg series where Mr. Pass shows off his stash.

The right stuff: Nelson Pass' droolworthy parts stash - YouTube

 

[codyt]

Thanks!

 

[Yurik_V]

Almost Germany amplifier. Transistors GT703 and GT705. Output power is about 50W. It is advisable to apply an operating amplifier with a supply voltage + -18 ... 24V.

 

[jpatay]

Yura, you used complementary pairs of germanium transistors and without general feedback? What is the quiescent current of each transistor? Is it stable?

 

[Yurik_V]

Stable. 100mA through one pair of transistor, total 200mA. Depending on the stubborn opamp, there may be 220 ... 230mA.

 

[jpatay]

Stable. 100mA through one pair of transistor, total 200mA. Depending on the stubborn opamp, there may be 220 ... 230mA.

I wish you a successful completion of the amplifier assembly. What box will it be in?

 

[Yurik_V]

Adjust the housing from the old amplifier.

 

[jpatay]

Adjust the housing from the old amplifier.

Fine!

 

[Zoran]

done!
this is when cranked up at 20volts with LM317 regulator
distortion dropped to 0.076%, intermodulation at 0.101%
I will build another version, with bigger heatsinks

Hi Adason. Could You please post the final shematic, preferably with some DC points measured and 2 resistances of bias pot measured? I cant find what part of Ge power transistor You used? Thanks

 

[rollingtube]

Hi Adason. Could You please post the final shematic, preferably with some DC points measured and 2 resistances of bias pot measured? I cant find what part of Ge power transistor You used? Thanks

From the pictures these are GT703A and GT705A (cyrillic markings).

 

[Zoran]

Hi thnas
But from the picture in post #436 it seems like power Ge is 2N3614
?

 

[Soundhappy]

Adjust the housing from the old amplifier.

Fantastic DIY work Best regards

 

[Soundhappy]

Interesting pdf. ebook with Germanium parts

https://ia801705.us.archive.org/1/items/siemens_202011/siemens.pdf

source : Siemens - Delivery Program 1973/7 : Siemens : Free Download, Borrow, and Streaming : Internet Archive

 

[Yurik_V]

Thanks, Soundhappy. To the finished device, I still need to do a lot.

 

[adason]

Hi Adason. Could You please post the final shematic, preferably with some DC points measured and 2 resistances of bias pot measured? I cant find what part of Ge power transistor You used? Thanks

Hi Zoran, sorry for late reply. I have not been following this thread anymore.
To be honest, i was not so happy with the result and i got distracted with other projects, especially those based on power jfet lu1014d. Since there was gb on adapters, and i got some jfets from Mr. NP, and bought many from aliexpress.
I built f1j and f3 with lu1014d. Great stuff.
Since i got plenty, i guilt headphone amp too.
I know its not germanium, so i am not going to post it. Just saying that the sound was way ahead, so i am finishing lu1014d into box, plus i will work on perfect power supply for it. I scavenged my germanium headphone amp for parts.
If you have lu1014d, build headphone amp i posted in 'whats on your bench tonight' thread. You will like it.
Its one of the best headphone amps i have (and i have about dozen icluding few shiit, acp+, whammy...).

 

[Soundhappy]

About Germanium transistors Transistor Structure: Bell Labs (1965) - YouTube