Pavel Dudek's (Upupa Epops) amplifiers

[peranders]

Hi!

Please use "contact us" at my homepage.

 

[CeeVee]

TKS

Hi again Pavel,

Thanks for everything,...i did not reply before to thank you because i have been away in the middle of the Atlantic....work!

 

[Upupa Epops]

You are welcome, Carlos 🙂 How do you like it ?

 

[jacco vermeulen]

The Atlantic ?

 

[Upupa Epops]

Not Jacco, I'm not talking about Atlantic, although sailfish and marlin are amazing... 😉

 

[oharmath]

DPA222 transistors questions

Hi All,

I'm planning to build the Pavel's design DPA222 power amp, but I found a problem with transistors availability for this amp. The suggested transistor types for Q11,Q14,Q19 / Q12,Q15,Q18 posistions are BF469/BF470 (philips ?) and for Q13/Q17 the 2SA1837/2SC4793 (sanyo ?). AFAIK, Philips stopped the production of BF4xx types aprox. 5 years ago and also it is difficult to get the Sanyo's. Has somebody tried to use a different types of transistors for the given positions, or any suggestions for replacements ?

Thanks, Oto

(amp schematics in attachment)

 

[Upupa Epops]

BF 469/470 and BF 471/472 are types, which are readily available. Sanyo's types are 2SA1371 and 2SC3468, but you can use alternative fast type, which have collector at pin 2 ( if you can use original PCB configuration... ).

 

[jacco vermeulen]

2SA1145/2SC2705.

Still no Pavel picture.

 

[CeeVee]

Atlantic

...There is a portuguese Air Traffic Control Center there, in the azores.

I have technical responsabilities there.....and yes fishing, diving is amazing there!

 

[oharmath]

Thanks for reply, Upupa

Sorry I did a mistake in previous post. The mentioned Sanyo's in Q13/Q17 positions are 2SA1540/2SC3955 (in TO126 package).
The suggested 2SA1371/2SC3468 are in TO92. Can I use them ?

 

[Upupa Epops]

Sanyo's in TO 92 are at position Q11/Q12...

 

[oharmath]

The 2SA1371/2SC3468 types are seems to be ok for Q11/Q22 (not placed on the heat sink). But, what about Q13/Q17? I found some transistors in TO126 package from Hitachi 2SB1109/2SD1609
(spec: 160V/0.1A/1.25W/140MHz/hFE=60/TO126) What do You think ?

 

[Upupa Epops]

Parametres are OK, but question will be probably availability of these devices....Who is supplier ?

 

[oharmath]

found them at www.vadas.cz, but they have just a minimal amount in stock

 

[oharmath]

Hi Pavel,

The Q13/Q17 question is not a problem anymore,
I did some research on the web, and found this types:

2SB649A/2SD669A 160V/1.5A/20W/140MHz/TO126
2SA1358/2SC3421 120V/1A/10W/120MHz/TO126
2SA1249/2SC3117 160V/1.5A/10W/120Mhz/TO126

All these types are available from a Slovak supplier avelmak.sk
and they have them on the stock.
I believe, I can also use these types as a BF469/BF470 replacement.

 

[AndrewT]

2SB649A/2SD669A 160V/1.5A/20W/140MHz/TO126
2SA1358/2SC3421 120V/1A/10W/120MHz/TO126
2SA1249/2SC3117 160V/1.5A/10W/120Mhz/TO126

Hi,
I don't know what supply voltage you intend using, but these drivers have very different SOA.
649 300mA @50V 143mA @70Vce
1358 140mA @50V 85mA @70Vce
1249 150mA @50V 70mA @70Vce

 

[Upupa Epops]

You can use every ones, in this circuit they work deep in SOAR...take cheapest ones... 😎

 

[oharmath]

Hi AndrewT,
The planned rail voltage is 40V, (65W@8ohm) & all tr.types mentioned in previous post seem to be ok for this supply voltage.
The cheapest ones are the 2SB649A/2SD669A types.
Now, I thinking about output stage modification of the DPA222,
because the BD911/BD912 types are not my favourite transistors in the market 🙂 (maybe, i will replace them with 2 pairs of more powerfull transistors in TO3P package)

 

[Upupa Epops]

I was using cca one thousand these transistors of both polarity with 100 % reliability ( never change them ) - do you need more ? 😎

 

[oharmath]

No doubts about reliability, I just simply don't like them (especially the TO220 package). And to use a 2x pairs of output transistors in TO3P, the PCB needs just a small modification.