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#1
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Heil Ohmega 400 transistors
I need replacement output and output driver transistors for a Heil Ohmega
400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? |
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#2
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Heil Ohmega 400 transistors
StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#3
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Heil Ohmega 400 transistors
StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#4
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Heil Ohmega 400 transistors
StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#5
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Heil Ohmega 400 transistors
"StewieGriffin" wrote in message
I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Here's an independent opinion in the matter: http://groups.google.com/groups?selm...s.teranews.com |
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#6
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Heil Ohmega 400 transistors
"StewieGriffin" wrote in message
I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Here's an independent opinion in the matter: http://groups.google.com/groups?selm...s.teranews.com |
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#7
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Heil Ohmega 400 transistors
"StewieGriffin" wrote in message
I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Here's an independent opinion in the matter: http://groups.google.com/groups?selm...s.teranews.com |
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#8
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Heil Ohmega 400 transistors
In article ,
Bob Urz wrote: StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Matching (or exceeding) the original device's HFE isn't enough. I have seen instances where new (superior) transistors were unstable and oscillated at high frequency where "originals" did not. The problem is that new devices frequently have decent gain at a far higher frequency than older ones. Sometimes the oscillation occurs only when the devices are being driven with (perfectly ordinary) signals. I would recommend some careful o'scope work whenever "better" devices are substituted, but I'd be pretty certain that new devices could be made to operate in the amplifier somehow. Isaac |
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#9
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Heil Ohmega 400 transistors
In article ,
Bob Urz wrote: StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Matching (or exceeding) the original device's HFE isn't enough. I have seen instances where new (superior) transistors were unstable and oscillated at high frequency where "originals" did not. The problem is that new devices frequently have decent gain at a far higher frequency than older ones. Sometimes the oscillation occurs only when the devices are being driven with (perfectly ordinary) signals. I would recommend some careful o'scope work whenever "better" devices are substituted, but I'd be pretty certain that new devices could be made to operate in the amplifier somehow. Isaac |
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#10
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Heil Ohmega 400 transistors
In article ,
Bob Urz wrote: StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Matching (or exceeding) the original device's HFE isn't enough. I have seen instances where new (superior) transistors were unstable and oscillated at high frequency where "originals" did not. The problem is that new devices frequently have decent gain at a far higher frequency than older ones. Sometimes the oscillation occurs only when the devices are being driven with (perfectly ordinary) signals. I would recommend some careful o'scope work whenever "better" devices are substituted, but I'd be pretty certain that new devices could be made to operate in the amplifier somehow. Isaac |
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#11
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Heil Ohmega 400 transistors
Isaac Wingfield wrote: In article , Bob Urz wrote: StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Matching (or exceeding) the original device's HFE isn't enough. I have seen instances where new (superior) transistors were unstable and oscillated at high frequency where "originals" did not. The problem is that new devices frequently have decent gain at a far higher frequency than older ones. Sometimes the oscillation occurs only when the devices are being driven with (perfectly ordinary) signals. I would recommend some careful o'scope work whenever "better" devices are substituted, but I'd be pretty certain that new devices could be made to operate in the amplifier somehow. Isaac True, there is no one step sliver bullet. And many older power transistors were not known for there exceptional specs. Scoping the outputs and looking for the oscillation or modulation on the waveforms is a good idea. Some capacitors may have to be added to the drivers or such to "slow down" a replacement if that's the case. Considering the option is a "NO FIX", i think it worth a shot. The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#12
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Heil Ohmega 400 transistors
Isaac Wingfield wrote: In article , Bob Urz wrote: StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Matching (or exceeding) the original device's HFE isn't enough. I have seen instances where new (superior) transistors were unstable and oscillated at high frequency where "originals" did not. The problem is that new devices frequently have decent gain at a far higher frequency than older ones. Sometimes the oscillation occurs only when the devices are being driven with (perfectly ordinary) signals. I would recommend some careful o'scope work whenever "better" devices are substituted, but I'd be pretty certain that new devices could be made to operate in the amplifier somehow. Isaac True, there is no one step sliver bullet. And many older power transistors were not known for there exceptional specs. Scoping the outputs and looking for the oscillation or modulation on the waveforms is a good idea. Some capacitors may have to be added to the drivers or such to "slow down" a replacement if that's the case. Considering the option is a "NO FIX", i think it worth a shot. The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#13
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Heil Ohmega 400 transistors
Isaac Wingfield wrote: In article , Bob Urz wrote: StewieGriffin wrote: I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? Are any of the old transistors good? If so, you may be able to reverse engineer the spec. If you have a schematic you can make some assumptions. What's the output topology? What's the rail voltages? Take the old good devices and use a transistor checker to determine HFE. With the HFE and the supply rail voltages, you should be in the ballpark spec wise to find something usable. Post what you know. Matching (or exceeding) the original device's HFE isn't enough. I have seen instances where new (superior) transistors were unstable and oscillated at high frequency where "originals" did not. The problem is that new devices frequently have decent gain at a far higher frequency than older ones. Sometimes the oscillation occurs only when the devices are being driven with (perfectly ordinary) signals. I would recommend some careful o'scope work whenever "better" devices are substituted, but I'd be pretty certain that new devices could be made to operate in the amplifier somehow. Isaac True, there is no one step sliver bullet. And many older power transistors were not known for there exceptional specs. Scoping the outputs and looking for the oscillation or modulation on the waveforms is a good idea. Some capacitors may have to be added to the drivers or such to "slow down" a replacement if that's the case. Considering the option is a "NO FIX", i think it worth a shot. The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#14
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Heil Ohmega 400 transistors
"Arny Krueger" wrote in message ...
(snip) Here's an independent opinion in the matter: And that is worth giving him better than your saying about a man that you couldn't hold his channel marking tape. Now you are being really ignorant. I have done sound for over twice as long as Heil did. He still operates Heil sound- selling low-fi mikes at Ham radio fests. He got out of Pro audio cause the competion was too stiff. If you want to credit him with assembling info and printing it OK. But the hero worship only shows up how much you don't know. I knew Heil and half a dozen people who worked for him. Most of them moved on as quick as they could. If you really want to see what a hack he was take a look at the Ohmega amps he built. Utter trash as was most of his gear. How good an amp the Ohmega is/was isn't the question here, so this isn't too ****in' helpful! I've known Bob Heil for years. No, he's not Rupert Neve. But musicians want stuff that's crappy for all kinds of reasons, nostalgia and image and virtual penis size along with "they want that sound". If the guy wants to fix an Ohmega, more power to him. There has flatly got to be a device (or, N and P devices) in the correct package that will work. Be fun to figure it out. |
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#15
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Heil Ohmega 400 transistors
"Arny Krueger" wrote in message ...
(snip) Here's an independent opinion in the matter: And that is worth giving him better than your saying about a man that you couldn't hold his channel marking tape. Now you are being really ignorant. I have done sound for over twice as long as Heil did. He still operates Heil sound- selling low-fi mikes at Ham radio fests. He got out of Pro audio cause the competion was too stiff. If you want to credit him with assembling info and printing it OK. But the hero worship only shows up how much you don't know. I knew Heil and half a dozen people who worked for him. Most of them moved on as quick as they could. If you really want to see what a hack he was take a look at the Ohmega amps he built. Utter trash as was most of his gear. How good an amp the Ohmega is/was isn't the question here, so this isn't too ****in' helpful! I've known Bob Heil for years. No, he's not Rupert Neve. But musicians want stuff that's crappy for all kinds of reasons, nostalgia and image and virtual penis size along with "they want that sound". If the guy wants to fix an Ohmega, more power to him. There has flatly got to be a device (or, N and P devices) in the correct package that will work. Be fun to figure it out. |
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#16
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Heil Ohmega 400 transistors
"Arny Krueger" wrote in message ...
(snip) Here's an independent opinion in the matter: And that is worth giving him better than your saying about a man that you couldn't hold his channel marking tape. Now you are being really ignorant. I have done sound for over twice as long as Heil did. He still operates Heil sound- selling low-fi mikes at Ham radio fests. He got out of Pro audio cause the competion was too stiff. If you want to credit him with assembling info and printing it OK. But the hero worship only shows up how much you don't know. I knew Heil and half a dozen people who worked for him. Most of them moved on as quick as they could. If you really want to see what a hack he was take a look at the Ohmega amps he built. Utter trash as was most of his gear. How good an amp the Ohmega is/was isn't the question here, so this isn't too ****in' helpful! I've known Bob Heil for years. No, he's not Rupert Neve. But musicians want stuff that's crappy for all kinds of reasons, nostalgia and image and virtual penis size along with "they want that sound". If the guy wants to fix an Ohmega, more power to him. There has flatly got to be a device (or, N and P devices) in the correct package that will work. Be fun to figure it out. |
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#17
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Heil Ohmega 400 transistors
"Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. |
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#18
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Heil Ohmega 400 transistors
"Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. |
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#19
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Heil Ohmega 400 transistors
"Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. |
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#20
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Heil Ohmega 400 transistors
TonyP wrote: "Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? Some earlier Phase linear amps used a germanium transistor in its pre driver stages as i recall. They also used some ****ty slow Delco To-3 outputs in some models. It all comes down to ID'ing the parts. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#21
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Heil Ohmega 400 transistors
TonyP wrote: "Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? Some earlier Phase linear amps used a germanium transistor in its pre driver stages as i recall. They also used some ****ty slow Delco To-3 outputs in some models. It all comes down to ID'ing the parts. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#22
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Heil Ohmega 400 transistors
TonyP wrote: "Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? Some earlier Phase linear amps used a germanium transistor in its pre driver stages as i recall. They also used some ****ty slow Delco To-3 outputs in some models. It all comes down to ID'ing the parts. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#23
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Heil Ohmega 400 transistors
Bob Urz wrote:
TonyP wrote: "Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? Some earlier Phase linear amps used a germanium transistor in its pre driver stages as i recall. They also used some ****ty slow Delco To-3 outputs in some models. It all comes down to ID'ing the parts. At the time, those triple diffused NPN's were considered quite fast. |
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#24
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Heil Ohmega 400 transistors
Bob Urz wrote:
TonyP wrote: "Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? Some earlier Phase linear amps used a germanium transistor in its pre driver stages as i recall. They also used some ****ty slow Delco To-3 outputs in some models. It all comes down to ID'ing the parts. At the time, those triple diffused NPN's were considered quite fast. |
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#25
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Heil Ohmega 400 transistors
Bob Urz wrote:
TonyP wrote: "Bob Urz" wrote in message ... The worst case scenario is trying to source some germanium transistors. Now that's a snipe hunt. A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? Some earlier Phase linear amps used a germanium transistor in its pre driver stages as i recall. They also used some ****ty slow Delco To-3 outputs in some models. It all comes down to ID'ing the parts. At the time, those triple diffused NPN's were considered quite fast. |
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#26
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Heil Ohmega 400 transistors
"Bob Urz" wrote in message ... TonyP wrote: A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? The OP did IIRC. TonyP. |
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#27
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Heil Ohmega 400 transistors
"Bob Urz" wrote in message ... TonyP wrote: A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? The OP did IIRC. TonyP. |
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#28
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Heil Ohmega 400 transistors
"Bob Urz" wrote in message ... TonyP wrote: A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? The OP did IIRC. TonyP. |
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#29
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Heil Ohmega 400 transistors
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#31
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Heil Ohmega 400 transistors
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#32
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Silicon vs. Germanium (was Heil Omega 400 transistors)
I wonder what it was that made silicon win out over germanium in solid state
technology. Back in the '60s, we used to see a lot of germanium transistors. Germanium has a lower p-n drop (0.2 volts vs. 0.6 for silicon) which could theoretically reduce power dissipation. In the late '70s and early '80s, there was a rectifier company that was making germanium rectifiers for power supplies because they were more efficient. So, what are the properties of silicon that make it superior to germanium? Easier to fabricate? More reliable? Higher power/current capability? Less temperature sensitive? cheaper/more plentiful? |
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#33
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Silicon vs. Germanium (was Heil Omega 400 transistors)
I wonder what it was that made silicon win out over germanium in solid state
technology. Back in the '60s, we used to see a lot of germanium transistors. Germanium has a lower p-n drop (0.2 volts vs. 0.6 for silicon) which could theoretically reduce power dissipation. In the late '70s and early '80s, there was a rectifier company that was making germanium rectifiers for power supplies because they were more efficient. So, what are the properties of silicon that make it superior to germanium? Easier to fabricate? More reliable? Higher power/current capability? Less temperature sensitive? cheaper/more plentiful? |
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#34
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Silicon vs. Germanium (was Heil Omega 400 transistors)
I wonder what it was that made silicon win out over germanium in solid state
technology. Back in the '60s, we used to see a lot of germanium transistors. Germanium has a lower p-n drop (0.2 volts vs. 0.6 for silicon) which could theoretically reduce power dissipation. In the late '70s and early '80s, there was a rectifier company that was making germanium rectifiers for power supplies because they were more efficient. So, what are the properties of silicon that make it superior to germanium? Easier to fabricate? More reliable? Higher power/current capability? Less temperature sensitive? cheaper/more plentiful? |
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#35
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Silicon vs. Germanium (was Heil Omega 400 transistors)
In article ,
Karl Uppiano wrote: I wonder what it was that made silicon win out over germanium in solid state technology. Back in the '60s, we used to see a lot of germanium transistors. Germanium has a lower p-n drop (0.2 volts vs. 0.6 for silicon) which could theoretically reduce power dissipation. In the late '70s and early '80s, there was a rectifier company that was making germanium rectifiers for power supplies because they were more efficient. So, what are the properties of silicon that make it superior to germanium? Easier to fabricate? More reliable? Higher power/current capability? Less temperature sensitive? cheaper/more plentiful? http://www.ti.com/corp/docs/company/...oduction.shtml gives one look at the question - it's a 1954 press release about silicon transistors. "Higher power", "less temperature-sensitive", and "cheaper" seem to be the high points. I believe that "more reliable", "lower reverse leakage" and "capable of operating at higher voltages" also come into it. These days, the popular solutions for rectifiers requiring low forward voltage drop seems to be to use either Schottky diodes (roughly half the forward drop of grown-junction silicon, I believe), or synchronous switched rectification using MOSFETs or IGBTs. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#36
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Silicon vs. Germanium (was Heil Omega 400 transistors)
In article ,
Karl Uppiano wrote: I wonder what it was that made silicon win out over germanium in solid state technology. Back in the '60s, we used to see a lot of germanium transistors. Germanium has a lower p-n drop (0.2 volts vs. 0.6 for silicon) which could theoretically reduce power dissipation. In the late '70s and early '80s, there was a rectifier company that was making germanium rectifiers for power supplies because they were more efficient. So, what are the properties of silicon that make it superior to germanium? Easier to fabricate? More reliable? Higher power/current capability? Less temperature sensitive? cheaper/more plentiful? http://www.ti.com/corp/docs/company/...oduction.shtml gives one look at the question - it's a 1954 press release about silicon transistors. "Higher power", "less temperature-sensitive", and "cheaper" seem to be the high points. I believe that "more reliable", "lower reverse leakage" and "capable of operating at higher voltages" also come into it. These days, the popular solutions for rectifiers requiring low forward voltage drop seems to be to use either Schottky diodes (roughly half the forward drop of grown-junction silicon, I believe), or synchronous switched rectification using MOSFETs or IGBTs. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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#37
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Silicon vs. Germanium (was Heil Omega 400 transistors)
In article ,
Karl Uppiano wrote: I wonder what it was that made silicon win out over germanium in solid state technology. Back in the '60s, we used to see a lot of germanium transistors. Germanium has a lower p-n drop (0.2 volts vs. 0.6 for silicon) which could theoretically reduce power dissipation. In the late '70s and early '80s, there was a rectifier company that was making germanium rectifiers for power supplies because they were more efficient. So, what are the properties of silicon that make it superior to germanium? Easier to fabricate? More reliable? Higher power/current capability? Less temperature sensitive? cheaper/more plentiful? http://www.ti.com/corp/docs/company/...oduction.shtml gives one look at the question - it's a 1954 press release about silicon transistors. "Higher power", "less temperature-sensitive", and "cheaper" seem to be the high points. I believe that "more reliable", "lower reverse leakage" and "capable of operating at higher voltages" also come into it. These days, the popular solutions for rectifiers requiring low forward voltage drop seems to be to use either Schottky diodes (roughly half the forward drop of grown-junction silicon, I believe), or synchronous switched rectification using MOSFETs or IGBTs. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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Heil Ohmega 400 transistors
Ken B wrote: In article , says... "Bob Urz" wrote in message ... TonyP wrote: A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? The OP did IIRC. TonyP. The OP said: Subject: Heil Ohmega 400 transistors From: StewieGriffin Newsgroups: rec.audio.tech I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? I think Bob Urz was the first mention of germanium transistors in particular. Just a note: i cannot say that this amp has or uses germanium transistors. I just remember trying to source them to fix some earlier high power Phase linears of a similar vintage. So, its just something to look out for. Especially since no one seems to have any information on this amp. And the Phase amps used them as a bias transistor or such, not outputs. I do remember some early to mid 60's hi-fi amps that had some though. As i recall, the output devices were relatively leaky and did not have a high voltage breakdown. Of course that was 60's fabrication and technology. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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Heil Ohmega 400 transistors
Ken B wrote: In article , says... "Bob Urz" wrote in message ... TonyP wrote: A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? The OP did IIRC. TonyP. The OP said: Subject: Heil Ohmega 400 transistors From: StewieGriffin Newsgroups: rec.audio.tech I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? I think Bob Urz was the first mention of germanium transistors in particular. Just a note: i cannot say that this amp has or uses germanium transistors. I just remember trying to source them to fix some earlier high power Phase linears of a similar vintage. So, its just something to look out for. Especially since no one seems to have any information on this amp. And the Phase amps used them as a bias transistor or such, not outputs. I do remember some early to mid 60's hi-fi amps that had some though. As i recall, the output devices were relatively leaky and did not have a high voltage breakdown. Of course that was 60's fabrication and technology. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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#40
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Heil Ohmega 400 transistors
Ken B wrote: In article , says... "Bob Urz" wrote in message ... TonyP wrote: A 400W power amp with germanium output transistors, do you know of any? TonyP. Did i say OUTPUTS? The OP did IIRC. TonyP. The OP said: Subject: Heil Ohmega 400 transistors From: StewieGriffin Newsgroups: rec.audio.tech I need replacement output and output driver transistors for a Heil Ohmega 400 power amp (1970's). The company no longer has stock, but I spoke with Bob Heil, and he said he has seen discussions on this amp in this NG. The part #s are proprietary, and he knows of no cross. Has anyone repaired this amp? I think Bob Urz was the first mention of germanium transistors in particular. Just a note: i cannot say that this amp has or uses germanium transistors. I just remember trying to source them to fix some earlier high power Phase linears of a similar vintage. So, its just something to look out for. Especially since no one seems to have any information on this amp. And the Phase amps used them as a bias transistor or such, not outputs. I do remember some early to mid 60's hi-fi amps that had some though. As i recall, the output devices were relatively leaky and did not have a high voltage breakdown. Of course that was 60's fabrication and technology. Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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