On Thu, 05 Jan 2017 12:07:25 -0500, Bob Engelhardt
wrote:

On 1/5/2017 11:14 AM, wrote:
If the transistor you need is a DTG600, NTE179 is a substitute and is germanium. I have one in stock if you want it. This is a TO-3 style transistor right?

The posted schematic was a bit fuzy, so if I have the part number wrong, please post the correct one.


The transistor is a DLG600. I remember seeing that the NTE179 was a
substitute, but the NTE179's that I found were just about as expensive.
Especially compared to the $0.48 for the TIP32C.

Try eBay for an NTE179:
http://www.ebay.com/sch/i.html?_nkw=nte179
Yep, expensive.

DLG600 is rated at 90V/25A, while the TIP32C at 100V/3A. That would
seem to be a rather poor choice for a substitute.

If you substitute silicon, you'll need to change some component values
to deal with the Vbe change from 0.3v to 0.6v. Probably doubling the
resistance of the 8.2 ohm sense resistor, and changing D7 from
germanium to silicon. Hopefully, the current ranges will remain the
same. The silicon device will have a better gain-bandwidth product,
so a few ferrite beads to keep the power xsistor from oscillating. If
you choose to use a different package, you'll need to do some creative
mounting and heat sinking. The analog series current limiting
transistor will dissipate considerable heat at high loads.

Sounds like too much work. I'll see if can find one in my junk pile.
I've been hoarding germanium devices for years for use in repairs.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558