Delco DS-501 Transistor Convector: Fabricate my own? (pictures)

11/15/2004 11:09:54 AMpgtr

Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)

I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.

I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?

If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).

I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.

Here are some pix...

http://www.world-net.net/~toddh/converter1.JPG
http://www.world-net.net/~toddh/converter2.JPG

thanks,

11/15/2004 11:59:33 AMRich, W3HWJ

A quick Google search tells me that this transistor is a Germanium PNP equivalent to 2N235. That may be hard to find because of the "doorknob" style of its case. I am sure you could find a Germanium PNP in a TO-3 case, and just re-drill your heatsink (called a "convector"). I seem to recall that 2N176 was a popular audio output transistor and maybe more available today. Good luck!

:Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
:
:I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
:
:I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
:
:If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
:
:I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
:
:Here are some pix...
:
:http://www.world-net.net/~toddh/converter1.JPG
:http://www.world-net.net/~toddh/converter2.JPG
:
:thanks,
:

11/15/2004 12:02:56 PMRich, W3HWJ

Here is a website selling old car radio transistors:
http://www.sphere.bc.ca/test/vintage.html

:A quick Google search tells me that this transistor is a Germanium PNP equivalent to 2N235. That may be hard to find because of the "doorknob" style of its case. I am sure you could find a Germanium PNP in a TO-3 case, and just re-drill your heatsink (called a "convector"). I seem to recall that 2N176 was a popular audio output transistor and maybe more available today. Good luck!
:
:
:
::Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
::
::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
::
::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
::
::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
::
::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
::
::Here are some pix...
::
::http://www.world-net.net/~toddh/converter1.JPG
::http://www.world-net.net/~toddh/converter2.JPG
::
::thanks,
::

11/15/2004 1:42:01 PM

Thanks! I googled but missed this - then I'm not all that electronics knowledgeable either :)

I have to scrounge up some old alum heat sink or other since I'm putting this together from scratch - how it mounts (or looks) doesn't matter as long as it works. I just need a pair of 'modern' or 'available' transisters (2N235) that I can wire up to the 3 wires for each of the 2 channels. I re-googled and did find a reference on another forum to DS-501 -> 2N442...FWIW.

I'll take the #s you mentioned w/ me and visit the local electronics store to see what I can come up w/.

thanks!

:A quick Google search tells me that this transistor is a Germanium PNP equivalent to 2N235. That may be hard to find because of the "doorknob" style of its case. I am sure you could find a Germanium PNP in a TO-3 case, and just re-drill your heatsink (called a "convector"). I seem to recall that 2N176 was a popular audio output transistor and maybe more available today. Good luck!

11/15/2004 1:50:36 PMpgtr

Thanks! I googled but missed this - then I'm not all that electronics knowledgeable either :)

I have to scrounge up some old alum heat sink or other since I'm putting this together from scratch - how it mounts (or looks) doesn't matter as long as it works. I just need a pair of 'modern' or 'available' transisters (2N235) that I can wire up to the 3 wires for each of the 2 channels. I re-googled and did find a reference on another forum to DS-501 -> 2N442...FWIW.

I'll take the #s you mentioned w/ me and visit the local electronics store to see what I can come up w/.

thanks!

:A quick Google search tells me that this transistor is a Germanium PNP equivalent to 2N235. That may be hard to find because of the "doorknob" style of its case. I am sure you could find a Germanium PNP in a TO-3 case, and just re-drill your heatsink (called a "convector"). I seem to recall that 2N176 was a popular audio output transistor and maybe more available today. Good luck!

11/15/2004 12:56:00 PMNat

It's not easy finding germanium transistors these days. They are noisy, have high leakage, are thermally unstable and require carefully designed bias feed-back circuits to prevent thermal run away. You can certainly duplicate the performance using modern silicon transistors, but I would not want to duplicate Delco's obsolete design.

:Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
:
:I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
:
:I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
:
:If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
:
:I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
:
:Here are some pix...
:
:http://www.world-net.net/~toddh/converter1.JPG
:http://www.world-net.net/~toddh/converter2.JPG
:
:thanks,
:

11/15/2004 1:48:36 PMpgtr

The stereos used a pair of these and mono units a single drive transistor.

I'd be interested in a pair of modern silicon equiv that I could simply substitute for these two(2)... any specific suggestions? The form factor doesn't matter since I'll be scrounging up a 'new' heat sink from wherever.

thanks,

: It's not easy finding germanium transistors these days. They are noisy, have high leakage, are thermally unstable and require carefully designed bias feed-back circuits to prevent thermal run away. You can certainly duplicate the performance using modern silicon transistors, but I would not want to duplicate Delco's obsolete design.

11/15/2004 2:11:32 PMNat

Well I'm not clear here when you say "the stereos used a pair of these and mono units a single drive transistor."

Do you have a total of 2 or 4 DS-501s? (see my note below).

As for substituting silicon, you will have to rebuilt the bias circuits. But if these are single-ended you would be much better off going to a push-pull design. I would just buy a amp at any car audio store. Even a cheap one would work better than anything you could built out of Delco's old design.

- Nat

:The stereos used a pair of these and mono units a single drive transistor.
:
:I'd be interested in a pair of modern silicon equiv that I could simply substitute for these two(2)... any specific suggestions? The form factor doesn't matter since I'll be scrounging up a 'new' heat sink from wherever.
:
:thanks,
:
:
:: It's not easy finding germanium transistors these days. They are noisy, have high leakage, are thermally unstable and require carefully designed bias feed-back circuits to prevent thermal run away. You can certainly duplicate the performance using modern silicon transistors, but I would not want to duplicate Delco's obsolete design.
:

11/15/2004 4:20:04 PM

:Well I'm not clear here when you say "the stereos used a pair of these and mono units a single drive transistor."

The AM/FM Stereo unit I have uses/needs the exact same convector in the pictures in my previous post:
http://www.world-net.net/~toddh/converter1.JPG
http://www.world-net.net/~toddh/converter2.JPG
I have a Stereo (not pictured) but am missing the (pictured) convector assembly.

They also made an AM/FM Mono version of this same radio. The mono unit (mine is stereo) came w/ a similar convector except with one(1) transistor. Essentially you could take a hacksaw and cut the one I have shown in the picture in half so to speak for the mono AM/FM radio.

:Do you have a total of 2 or 4 DS-501s?

Two(2). See: http://www.world-net.net/~toddh/converter1.JPG

:As for substituting silicon, you will have to rebuilt the bias circuits.

I'll keep that in mind but probably more than I can attempt - I was hoping I could just select a pair of silicon transistors of same/similar value to the old DS-501s and substitute them. That or maybe find some DS-501s on the cheap somewhere or other if I had to.

The radio is perfectly fine for my limited needs if can find a pair of transistors to fabricate the missing convector with. Not sure I'm up for doing anything more radical than this for the time being.

To fabricate I need:
1) piece of aluminum heatsink (easy to find)
2) two(2) caps (should be a std value)
3) some wire, solder, connector etc...
4) two(2) Delco DS-501 or equivalent/similar vintage or modern transistors

If I can source #4 the rest should be trivial - the radio sounds plenty good enough for my needs and has been running extensively using a 'borrowed' convector from someone w/ the same radio.

:But if these are single-ended you would be much better off going to a push-pull design. I would just buy a amp at any car audio store. Even a cheap one would work better than anything you could built out of Delco's old design.

11/15/2004 9:01:38 PMpgtr

:Well I'm not clear here when you say "the stereos used a pair of these and mono units a single drive transistor."

The AM/FM Stereo unit I have uses/needs the exact same convector in the pictures in my previous post:
http://www.world-net.net/~toddh/converter1.JPG
http://www.world-net.net/~toddh/converter2.JPG
I have a Stereo (not pictured) but am missing the (pictured) convector assembly.

They also made an AM/FM Mono version of this same radio. The mono unit (mine is stereo) came w/ a similar convector except with one(1) transistor. Essentially you could take a hacksaw and cut the one I have shown in the picture in half so to speak for the mono AM/FM radio.

:Do you have a total of 2 or 4 DS-501s?

Two(2). See: http://www.world-net.net/~toddh/converter1.JPG

:As for substituting silicon, you will have to rebuilt the bias circuits.

I'll keep that in mind but probably more than I can attempt - I was hoping I could just select a pair of silicon transistors of same/similar value to the old DS-501s and substitute them. That or maybe find some DS-501s on the cheap somewhere or other if I had to.

The radio is perfectly fine for my limited needs if can find a pair of transistors to fabricate the missing convector with. Not sure I'm up for doing anything more radical than this for the time being.

To fabricate I need:
1) piece of aluminum heatsink (easy to find)
2) two(2) caps (should be a std value)
3) some wire, solder, connector etc...
4) two(2) Delco DS-501 or equivalent/similar vintage or modern transistors

If I can source #4 the rest should be trivial - the radio sounds plenty good enough for my needs and has been running extensively using a 'borrowed' convector from someone w/ the same radio.

:But if these are single-ended you would be much better off going to a push-pull design. I would just buy a amp at any car audio store. Even a cheap one would work better than anything you could built out of Delco's old design.

11/15/2004 9:27:11 PMNat

::Do you have a total of 2 or 4 DS-501s?
:
:Two(2). See: http://www.world-:net.net/~toddh/converter1.JPG

Well it is- as I suspected- two single-ended outputs rather than one push-pull.
That heat sink will be dissipating about 24 watts just from the transistors's idle current.

:
:
:I'll keep that in mind but probably more than I can attempt - I was hoping I could just select a pair of silicon transistors of same/similar value to the old DS-501s and substitute them.

You will not find any silicon transistor that will replace a germanium without modifying the bias. Germaniums used 0.2-vlt bias- silicon about 0.65-vlts.

Furthermore I've never seen a silicon in a TO-1 can. There may be such critters but I don't know of one.
You are more likely to find one in a TO-3 can, but these will less current capacity.

:That or maybe find some DS-501s on the cheap :somewhere or other if I had to.
:
:

Well if you did they would probably be leaky. Germanium power transistors were very prone to develop leakage as they aged. We are talking about 30 year old stuff here.

11/15/2004 1:10:48 PMNat

I will add that Delco was notorious for using inefficient single-ended "class-A" output circuits. Being a stereo- those are likely two single-ended outputs rather than a push-pull. And they draw about an amp a piece idle current(!) and probably put out no more than 3-4 watts per channel. A terribly inefficient design by today's standards.

:Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
:
:I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
:
:I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
:
:If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
:
:I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
:
:Here are some pix...
:
:http://www.world-net.net/~toddh/converter1.JPG
:http://www.world-net.net/~toddh/converter2.JPG
:
:thanks,
:

11/15/2004 11:06:45 PMEdd

If you can find an electronics part supplier that has some of the old ECG replacement semi line line or the newer NTE spinoff the DS501 was second sourced as a NTE 105 in the doorknob (TO-36) package .
If going for a TO-3 an ECG/NTE 121 would fill the bill.
Seems like I even have some of the Military version TO-36 cased units socked away in storage.
Can you provide a model of the radio for schematic research ?
73's de Edd

:I will add that Delco was notorious for using
inefficient single-ended "class-A" output circuits. Being a stereo- those are likely two single-ended outputs rather than a push-pull. And they draw about an amp a piece idle current(!) and probably put out no more than 3-4 watts per channel. A terribly inefficient design by today's standards.
:
:
::Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
::
::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
::
::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
::
::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
::
::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
::
::Here are some pix...
::
::http://www.world-net.net/~toddh/converter1.JPG
::http://www.world-net.net/~toddh/converter2.JPG
::
::thanks,
::

11/15/2004 11:57:48 PMpgtr

Thanks. Packaging doesn't matter to me as long as I can mount it to some sort of external hunk of alum and wire it to the 6 existing wires is all. I just want something functional.

This radio apparently existed w/ little change between 1968 and 1976 with both an AM/FM Mono version and an AM/FM Stereo version. These all used the same external convector - Here's the Stereo part#s - take your pick: (the one I have is a 661).

1968-71 GM #7303211
72 GM #7937581
73 GM #9341341
1974-76 GM #9344661

I don't have a GM# or better yet Delco# for the DS-501 transistor. If you happen to have one or look one up that would be very helpful as I might know where there's some NOS Delco parts in storage...

thanks!

:If you can find an electronics part supplier that has some of the old ECG replacement semi line line or the newer NTE spinoff the DS501 was second sourced as a NTE 105 in the doorknob (TO-36) package .
:If going for a TO-3 an ECG/NTE 121 would fill the bill.
:Seems like I even have some of the Military version TO-36 cased units socked away in storage.
:Can you provide a model of the radio for schematic research ?
:73's de Edd

11/19/2004 5:03:49 PMradiodoc

:Thanks. Packaging doesn't matter to me as long as I can mount it to some sort of external hunk of alum and wire it to the 6 existing wires is all. I just want something functional.
:
:This radio apparently existed w/ little change between 1968 and 1976 with both an AM/FM Mono version and an AM/FM Stereo version. These all used the same external convector - Here's the Stereo part#s - take your pick: (the one I have is a 661).
:
:1968-71 GM #7303211
:72 GM #7937581
:73 GM #9341341
:1974-76 GM #9344661
:
:I don't have a GM# or better yet Delco# for the DS-501 transistor. If you happen to have one or look one up that would be very helpful as I might know where there's some NOS Delco parts in storage...
:
:thanks!
:
:
:
:
::If you can find an electronics part supplier that has some of the old ECG replacement semi line line or the newer NTE spinoff the DS501 was second sourced as a NTE 105 in the doorknob (TO-36) package .
::If going for a TO-3 an ECG/NTE 121 would fill the bill.
::Seems like I even have some of the Military version TO-36 cased units socked away in storage.
::Can you provide a model of the radio for schematic research ?
::73's de Edd
:
:pgtr,

I have been reading your discussion about the Delco DS-501. Pgtr I have looked in my junk box and found a U or channel shaped aluminum heatsink with a couple of GE 5490810 transistors and mounting hardware on it I do not need. This GE transistor assembly was used in an external weather proof 10 watt speaker for GE mobile radios. The GE transistor is the equivilant to the NTE-105 transistor. Perhaps you may have a use for the whole assembly. Let me know here or send me an email to radiodoc@alltel.net.

radiodoc

:

12/12/2004 1:32:24 AMRadio Joe

I might have somethinng laying around for your radio. Email Me at j_cilluffo@yahoo.com

::Thanks. Packaging doesn't matter to me as long as I can mount it to some sort of external hunk of alum and wire it to the 6 existing wires is all. I just want something functional.
::
::This radio apparently existed w/ little change between 1968 and 1976 with both an AM/FM Mono version and an AM/FM Stereo version. These all used the same external convector - Here's the Stereo part#s - take your pick: (the one I have is a 661).
::
::1968-71 GM #7303211
::72 GM #7937581
::73 GM #9341341
::1974-76 GM #9344661
::
::I don't have a GM# or better yet Delco# for the DS-501 transistor. If you happen to have one or look one up that would be very helpful as I might know where there's some NOS Delco parts in storage...
::
::thanks!
::
::
::
::
:::If you can find an electronics part supplier that has some of the old ECG replacement semi line line or the newer NTE spinoff the DS501 was second sourced as a NTE 105 in the doorknob (TO-36) package .
:::If going for a TO-3 an ECG/NTE 121 would fill the bill.
:::Seems like I even have some of the Military version TO-36 cased units socked away in storage.
:::Can you provide a model of the radio for schematic research ?
:::73's de Edd
::
::pgtr,
:
:I have been reading your discussion about the Delco DS-501. Pgtr I have looked in my junk box and found a U or channel shaped aluminum heatsink with a couple of GE 5490810 transistors and mounting hardware on it I do not need. This GE transistor assembly was used in an external weather proof 10 watt speaker for GE mobile radios. The GE transistor is the equivilant to the NTE-105 transistor. Perhaps you may have a use for the whole assembly. Let me know here or send me an email to radiodoc@alltel.net.
:
:radiodoc
:
::

4/29/2009 4:59:16 PMscott romano

I have the ds-501 unit in your posting, if you still need one. Thanks-scott

:I will add that Delco was notorious for using inefficient single-ended "class-A" output circuits. Being a stereo- those are likely two single-ended outputs rather than a push-pull. And they draw about an amp a piece idle current(!) and probably put out no more than 3-4 watts per channel. A terribly inefficient design by today's standards.
:
:
::Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
::
::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
::
::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
::
::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
::
::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
::
::Here are some pix...
::
::http://www.world-net.net/~toddh/converter1.JPG
::http://www.world-net.net/~toddh/converter2.JPG
::
::thanks,
::

7/16/2011 5:33:47 PMmike banner

:I will add that Delco was notorious for using inefficient single-ended "class-A" output circuits. Being a stereo- those are likely two single-ended outputs rather than a push-pull. And they draw about an amp a piece idle current(!) and probably put out no more than 3-4 watts per channel. A terribly inefficient design by today's standards.
:
:
::Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
::
::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
::
::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
::
::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
::
::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
::
::Here are some pix...
::
::http://www.world-net.net/~toddh/converter1.JPG
::http://www.world-net.net/~toddh/converter2.JPG
::
::thanks,
::

7/16/2011 6:18:22 PMmike banner

::I will add that Delco was notorious for using inefficient single-ended "class-A" output circuits. Being a stereo- those are likely two single-ended outputs rather than a push-pull. And they draw about an amp a piece idle current(!) and probably put out no more than 3-4 watts per channel. A terribly inefficient design by today's standards.
::
::
:::Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
:::
:::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
:::
:::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
:::
:::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
:::
:::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
:::
:::Here are some pix...
:::
:::http://www.world-net.net/~toddh/converter1.JPG
:::http://www.world-net.net/~toddh/converter2.JPG
:::
:::thanks,
:::
:
the speaker should be 3.2 ohms...because of limited voltage out, this load is critical to get full output. A similar transistor in the TO-3 case is the DS-503. Both are germanium aloy, 90 watt colector, and have been used in the same delco circuit design.

7/16/2011 6:21:55 PMmike banner

:::I will add that Delco was notorious for using inefficient single-ended "class-A" output circuits. Being a stereo- those are likely two single-ended outputs rather than a push-pull. And they draw about an amp a piece idle current(!) and probably put out no more than 3-4 watts per channel. A terribly inefficient design by today's standards.
:::
:::
::::Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
::::
::::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
::::
::::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
::::
::::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
::::
::::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
::::
::::Here are some pix...
::::
::::http://www.world-net.net/~toddh/converter1.JPG
::::http://www.world-net.net/~toddh/converter2.JPG
::::
::::thanks,
::::
::
:the speaker should be 3.2 ohms...because of limited voltage out, this load is critical to get full output. A similar transistor in the TO-3 case is the DS-503. Both are germanium aloy, 90 watt colector, and have been used in the same delco circuit design.
:
ds501 crosses to NTE105, ds503 crosses to nte121...

7/16/2011 6:33:35 PMmike banner

::::I will add that Delco was notorious for using inefficient single-ended "class-A" output circuits. Being a stereo- those are likely two single-ended outputs rather than a push-pull. And they draw about an amp a piece idle current(!) and probably put out no more than 3-4 watts per channel. A terribly inefficient design by today's standards.
::::
::::
:::::Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
:::::
:::::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
:::::
:::::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
:::::
:::::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
:::::
:::::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
:::::
:::::Here are some pix...
:::::
:::::http://www.world-net.net/~toddh/converter1.JPG
:::::http://www.world-net.net/~toddh/converter2.JPG
:::::
:::::thanks,
:::::
:::
::the speaker should be 3.2 ohms...because of limited voltage out, this load is critical to get full output. A similar transistor in the TO-3 case is the DS-503. Both are germanium aloy, 90 watt colector, and have been used in the same delco circuit design.
::
:ds501 crosses to NTE105, ds503 crosses to nte121 because these transistors are germanium, the barrier voltage is only .2 volt instead of .6 volt on silicon transistors now in use.

9/6/2013 2:55:36 AMCayce

I have some DS-503

12/13/2004 9:41:14 PMNick

:Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
:
:I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
:RCA used to have a line of replacement transistors called 'SK series' They list an SK3012 as a replacement for a DS501. I have two 'new' Sk3012 transistors if you are interested - email me at n.senker@worldnet.att.net.
:I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
:
:If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
:
:I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
:
:Here are some pix...
:
:http://www.world-net.net/~toddh/converter1.JPG
:http://www.world-net.net/~toddh/converter2.JPG
:
:thanks,
:

12/13/2004 10:12:00 PMNick

:Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
:
:I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
:
:I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
:
:If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
:
:I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
:
:Here are some pix...
:
:http://www.world-net.net/~toddh/converter1.JPG
:http://www.world-net.net/~toddh/converter2.JPG
:
:thanks,
:
RCA used to have a line of replacement transistors called 'SK series' They list an SK3012 as a replacement for a DS501. I have two 'new' Sk3012 transistors if you are interested - email me at n.senker@worldnet.att.net

4/29/2009 5:10:30 PMLou

:Boy does this bring back memories.

I still have a GM 8 track stereo deck that belonged to a Buick in the 60s. I had to replace the germanium power transistors because they were horribly distorting the audio.

I found the replacement part in the most unlikely place - RADIO SHACK. These equivalents were germanium and the heatsinks did not require modification. If I can find the unit, I will get a number off the transistors. Just goes to show don't throw ANYTHING away.

Lou

:Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
::
::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
::
::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
::
::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
::
::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
::
::Here are some pix...
::
::http://www.world-net.net/~toddh/converter1.JPG
::http://www.world-net.net/~toddh/converter2.JPG
::
::thanks,
::
:RCA used to have a line of replacement transistors called 'SK series' They list an SK3012 as a replacement for a DS501. I have two 'new' Sk3012 transistors if you are interested - email me at n.senker@worldnet.att.net

4/29/2009 9:11:00 PMMarv Nuce

Lou,
Every once in a while you can find a winning solution at Rad Shak, but not often. I haven't given up completely on them, and still find solutions there, but long for the days they were a big parts warehouse in Kansas.

marv

::Boy does this bring back memories.
:
:I still have a GM 8 track stereo deck that belonged to a Buick in the 60s. I had to replace the germanium power transistors because they were horribly distorting the audio.
:
:I found the replacement part in the most unlikely place - RADIO SHACK. These equivalents were germanium and the heatsinks did not require modification. If I can find the unit, I will get a number off the transistors. Just goes to show don't throw ANYTHING away.
:
:Lou
:
:
::Anybody heard of Delco DS-501 transistor or know if there is an 'equivalent' available? (cheap?)
:::
:::I have an old early 1970s (72-76) GM Delco AM/FM car radio/stereo that requires an external 'convector' (called that by Delco radio repair book). I do NOT have this convector for the radio. See pictures: It's a large external alum heatsink w/ two(2) large DS-501 transistors on it along w/ a pair of caps.
:::
:::I wonder if I can fabricate an equivalent unit out of modern transistors? A heat sink and the caps shouldn't be a problem. I'm guessing all I need is a pair of large Delco DS-501 transistors or modern equiv mounted heatsink and 6 wires (3 for each transistor) going to the radio unit. The problem is that DS-501s are not growing on trees AFAIK. That's why I'm wondering if a modern pair of transistors could be substituted?
:::
:::If it helps... it's obviously a 12V radio and requires 10 ohm speakers (8 ohm will do).
:::
:::I have access to one such 'convector' I can inspect. I've cleaned the radio up and it works great w/ the 'borrowed' convector.
:::
:::Here are some pix...
:::
:::http://www.world-net.net/~toddh/converter1.JPG
:::http://www.world-net.net/~toddh/converter2.JPG
:::
:::thanks,
:::
::RCA used to have a line of replacement transistors called 'SK series' They list an SK3012 as a replacement for a DS501. I have two 'new' Sk3012 transistors if you are interested - email me at n.senker@worldnet.att.net