Alternative transistors for DoZ?

[Cradle22]

Hi!

Since today I got a verrrrry big heatsink (I think it must have a rating of about 0.2 C/W) for virtually doodley squat 🙂 🙂 , I want to start a second attempt upond building the DoZ from ESP (boards already available).


I HAD planned to use 4 * MJ15003, but since my biggie heatsink has fins on BOTH sides 😉 😉 , fitting TO3 cases will be a pain in the *** (sadly, as usual, I have no DigiCam available to show you that sink).

But TOP3 cases, or anything which can be directly mounted to the sink's surface will be OK, it is even tapped already (must've been used in some industrial machinery before).

Elliot mentions 2N3055 (TO3), 2SC3281 (don't know, and hard to obtain for me) and MJ15003 (TO3, easy to get, but hard to fit...) for the DoZ...

Does someone here have any more recommendations for output transistors, not in TO3 case? With about the same power rating as the MJ15003, and no circuitry changes required (I already have all the other parts)?

Oh, btw., here in Germany I order from Reichelt, Farnell or RS Components, so it is preferred that one of them has them in stock...

Thanks a lot!

Arndt


Oh, btw., do you think my big sink (OK, at last here a description: 35 cm (in direction of the fins) * 22 cm, 10 cm thick (fins on both sides...), plate is 1 cm thick, weight 6 kg) will suffice for mounting all four power transistors for a stereo amp on it? Sadly I lost the auction for the second sink...

 

[moamps]

Elliot mentions 2N3055 (TO3), 2SC3281 (don't know, and hard to obtain for me) and MJ15003 (TO3, easy to get, but hard to fit...) for the DoZ...
Does someone here have any more recommendations for output transistors, not in TO3 case? With about the same power rating as the MJ15003, and no circuitry changes required (I already have all the other parts)?

Hi,

MJL3281 ( Farnell 708-495) or MJL21194 (Farnell 162-267)

Regards

 

[Cradle22]

Hi!

Thanks for your reply. Checked those transistors out (already heard of them).

Nice, and what I need, but 7 ? per piece 🙁

Think before trying them I will fiddle around with some old 3055 TO3 and an L-bar, seeing if there's really no way to get TO3 cases bolted to my sink... with cables still attachable that is 😉

Bye,

Arndt

 

[Asen]

Read carefully what Geoff says about the use of 2SC3281 in the JLH SE amp. I use such Toshiba transistor successfully in the old version 10 Watt-er. These 35MHz transistors are maybe not the best choice for the 15W version.

 

[MikeW]

Try the MJL 21194.😎

http://www.onsemi.com/pub/Collateral/MJL21193-D.PDF

 

[Cradle22]

Hi!

Read carefully what Geoff says about the use of 2SC3281 in the JLH SE amp. I use such Toshiba transistor successfully in the old version 10 Watt-er. These 35MHz transistors are maybe not the best choice for the 15W version.

Read the comments on the class-A site (took me some minutes to find out whom you meant with Geoff...) , and it seems that MJ15003 really would be my first choice (and they are cheap at Reichelt in Germany, about 1.5 Euro a piece, though not from Motorola, but no fakes... they've been working in my P3A now for one month under harsh conditions without failure)... not turning back from a challenge... there is about 3mm space between those fins of the sink and the bottom of an L-bar with TO3 cases mounted on top... now, if I shorten the pins of the TO3 cases as much that they don't protude from the mounting bar, maybe I can use them...

But has to wait until weekend until I can try it, too much work to do... :-(

Thanks!

Arndt

 

[Audiofanatic]

Perhaps this will help you.

I don't know who is the owner, I found it on the internet.
Looks like Peter Daniels work.

Look at the TO3 transistors beneath the heatsinks.

Audiofanatic 😉

 

[Mattyo5]

I'm using the 2sc5200's ....8! of them per channel....10 if you could the drivers 🙂 Rod said that it'd be a good idea to use these for drivers especially if I'm gonna drive more than 2 output transistors per channel. The best part...since my rail voltage will be around 50v, I'll be gettin 35wpc (or thereabouts) out of the DOZ. Anyway, the 2sc5200's are $1.80 us ...not bad from digikey. Don't know how easy it is to get those in Germany though. Later!

-Matthew K. Olson

 

[Cradle22]

Hi!

Thanks for all the suggestions, I really appreciate the help I get in this forum...

One thing that comes to my mind after looking at some transistors,

HOW can I determine if a transistors is suitable for replacing another one? What parts of the specs have to be similar?

Could I for example use the legendary 2SC2922 from Sanken (not that I would want to use them, at their price...)?

I I had a guideline like this, I could go on hunt by myself...??

Bye,

Arndt