I'm looking for a source of obselete semiconductors. I'm sure many of us have the problem, sooner or later.
I need to find a HPA 2034 diode. I've heard that it was made by Hewlett Packard. I doubt that, because as far as I know, they never made (or sourced) semiconductors. I need other semiconductors for a Model 18 Marantz. Anyone found any sources? It's gotten to the point where it's easy to fix tube equipment, but try vintage transistor equipment, good luck

Regards,

Gene

Hi Gene

HP did make diodes but I don't find your number. The good thing being diodes are interchangeable. If a detector, germanium will work. If power supply, high voltage silicon. As a zener you would need the regulating voltage. Where is the diode in your circuit? Knowing that, maybe someone can help.

Norm

: I'm looking for a source of obselete semiconductors. I'm sure many of us have the problem, sooner or later.
: I need to find a HPA 2034 diode. I've heard that it was made by Hewlett Packard. I doubt that, because as far as I know, they never made (or sourced) semiconductors. I need other semiconductors for a Model 18 Marantz. Anyone found any sources? It's gotten to the point where it's easy to fix tube equipment, but try vintage transistor equipment, good luck

: Regards,

: Gene

: Hi Gene

: HP did make diodes but I don't find your number. The good thing being diodes are interchangeable. If a detector, germanium will work. If power supply, high voltage silicon. As a zener you would need the regulating voltage. Where is the diode in your circuit? Knowing that, maybe someone can help.

: Norm

:
: : I'm looking for a source of obselete semiconductors. I'm sure many of us have the problem, sooner or later.
: : I need to find a HPA 2034 diode. I've heard that it was made by Hewlett Packard. I doubt that, because as far as I know, they never made (or sourced) semiconductors. I need other semiconductors for a Model 18 Marantz. Anyone found any sources? It's gotten to the point where it's easy to fix tube equipment, but try vintage transistor equipment, good luck

: : Regards,

: : Gene

Norm:
This diode is a detector in a Marantz 10B. I've been told that nothing but the original diode will do properly, (Otherwise it will need a re-align), I would prefer using the original, (Or a exact replacement)

Regards,

Gene Lambert

Hi,
If in doubt, try the old reliabe 1N34's.

If it is a quadrature detector, it makes zero difference, just make sure to replace all four diodes. If it is a ratio detector, you still have a bit of lattitude, if tuning is at all affected here, it will have more impact on your channel sepration, than it will on the actual dial. Most people would never notice a difference, and those who claim to hear the difference between .01THD, and .1THD can be disregarded. (as a general rule). In seriousness, any reciever with any age, or any amount of handling will be out of alignment.

If you want to be precise about it, you can retune the whole unit, it is not as daunting as it sounds, as you would be peaking your IF transformers, calibrating your tuning dial to track correctly, and centering that last stage for maximum channel seperation (19Khz). You can sometimes do an adequate job tuning by ear, but you need to have a really good ear to start.

If it were me- do the swap, you can always change them out later- and see if you can hear adequate channel seperation on a familiar piece of classical music (Ina Godda Davida does not count as classical), More than likely you will hear more than adequate seperation.

: : Hi Gene

: : HP did make diodes but I don't find your number. The good thing being diodes are interchangeable. If a detector, germanium will work. If power supply, high voltage silicon. As a zener you would need the regulating voltage. Where is the diode in your circuit? Knowing that, maybe someone can help.

: : Norm

: :
: : : I'm looking for a source of obselete semiconductors. I'm sure many of us have the problem, sooner or later.
: : : I need to find a HPA 2034 diode. I've heard that it was made by Hewlett Packard. I doubt that, because as far as I know, they never made (or sourced) semiconductors. I need other semiconductors for a Model 18 Marantz. Anyone found any sources? It's gotten to the point where it's easy to fix tube equipment, but try vintage transistor equipment, good luck

: : : Regards,

: : : Gene

: Norm:
: This diode is a detector in a Marantz 10B. I've been told that nothing but the original diode will do properly, (Otherwise it will need a re-align), I would prefer using the original, (Or a exact replacement)

: Regards,

: Gene Lambert

:Here is some information provided by the designer of your tuner, Dick Sequerra, relating to the purpose of those four diodes that might help you: "The ring bridge mixer was my idea. Ring modulators were developed many years before that, the Germans had used them, but the problem was we didn't have diodes of sufficient quality. Then Hewlett-Packard introduced hot-carrier diodes for use in military and instrumentation electronics. We were the first people to use these in a consumer product. They were terribly expensive. We traded off conversion gain to be able to balance out the common-mode anomalies, and it was designed with that in mind." The previous was excerpted from issue five of Vacuum Tube Valley. Before you tamper with these circuits, I strongly urge you to contact someone who can obtain exact matched replacements as the 10B is a very sensitive and balanced device. Not to mention they're worth quite a bit of money these days. Any old diode could throw performance way off if the unit worked at all. Issue five of VTV contains a full schematic and suggests anyone needing their 10B's serviced contact Tom Cadawas at 718-981-9138. He was the service manager at Marantz from '64 'til '74.
: Hi,
: If in doubt, try the old reliabe 1N34's.

: If it is a quadrature detector, it makes zero difference, just make sure to replace all four diodes. If it is a ratio detector, you still have a bit of lattitude, if tuning is at all affected here, it will have more impact on your channel sepration, than it will on the actual dial. Most people would never notice a difference, and those who claim to hear the difference between .01THD, and .1THD can be disregarded. (as a general rule). In seriousness, any reciever with any age, or any amount of handling will be out of alignment.

: If you want to be precise about it, you can retune the whole unit, it is not as daunting as it sounds, as you would be peaking your IF transformers, calibrating your tuning dial to track correctly, and centering that last stage for maximum channel seperation (19Khz). You can sometimes do an adequate job tuning by ear, but you need to have a really good ear to start.

: If it were me- do the swap, you can always change them out later- and see if you can hear adequate channel seperation on a familiar piece of classical music (Ina Godda Davida does not count as classical), More than likely you will hear more than adequate seperation.

:
: : : Hi Gene

: : : HP did make diodes but I don't find your number. The good thing being diodes are interchangeable. If a detector, germanium will work. If power supply, high voltage silicon. As a zener you would need the regulating voltage. Where is the diode in your circuit? Knowing that, maybe someone can help.

: : : Norm

: : :
: : : : I'm looking for a source of obselete semiconductors. I'm sure many of us have the problem, sooner or later.
: : : : I need to find a HPA 2034 diode. I've heard that it was made by Hewlett Packard. I doubt that, because as far as I know, they never made (or sourced) semiconductors. I need other semiconductors for a Model 18 Marantz. Anyone found any sources? It's gotten to the point where it's easy to fix tube equipment, but try vintage transistor equipment, good luck

: : : : Regards,

: : : : Gene

: : Norm:
: : This diode is a detector in a Marantz 10B. I've been told that nothing but the original diode will do properly, (Otherwise it will need a re-align), I would prefer using the original, (Or a exact replacement)

: : Regards,

: : Gene Lambert

Although Hewlett-Packard makes LOTS of diodes, especially in the optoelectronics area, I don't think that the HPA prefix is theirs. Codi Semiconductor in Linden NJ has a few diodes with that prefix according to my D.A.T.A. book. I don't even know if Codi is still in business and my book doesn't show your number.

Dean

By the way, as an interesting note, I'm told that hp's tunnel diode line was doing beautifully until one day, they began to have 0% yield, as though they no longer knew how to make tunnel diodes. After checking and rechecking their equipment and supplies, they found out that over that weekend, Palo Alto had begun floridating their water and it was affecting one of their processes. The story may be apocryphal, of course, but hey, it's kinda cute.

Hi Gene, Finding replacement semiconductors can be a real headache sometimes, though with diodes and transistors you can usually find good substitutes. I doubt if you'd have too much trouble finding a replacement for the detector with the same performance. Try NTE electronics at http://WWW.NTEINC.COM/ they specialize in replacement parts and often have eqivalents when no one else can supply. Their price is higher but that's better than not being able to get it at all and just reflects the problem of stocking rare parts that only sell in small quantities. Don Black.

: I'm looking for a source of obselete semiconductors. I'm sure many of us have the problem, sooner or later.
: I need to find a HPA 2034 diode. I've heard that it was made by Hewlett Packard. I doubt that, because as far as I know, they never made (or sourced) semiconductors. I need other semiconductors for a Model 18 Marantz. Anyone found any sources? It's gotten to the point where it's easy to fix tube equipment, but try vintage transistor equipment, good luck

: Regards,

: Gene

: Hi Gene, Finding replacement semiconductors can be a real headache sometimes, though with diodes and transistors you can usually find good substitutes. I doubt if you'd have too much trouble finding a replacement for the detector with the same performance. Try NTE electronics at http://WWW.NTEINC.COM/ they specialize in replacement parts and often have eqivalents when no one else can supply. Their price is higher but that's better than not being able to get it at all and just reflects the problem of stocking rare parts that only sell in small quantities. Don Black.

: : I'm looking for a source of obselete semiconductors. I'm sure many of us have the problem, sooner or later.
: : I need to find a HPA 2034 diode. I've heard that it was made by Hewlett Packard. I doubt that, because as far as I know, they never made (or sourced) semiconductors. I need other semiconductors for a Model 18 Marantz. Anyone found any sources? It's gotten to the point where it's easy to fix tube equipment, but try vintage transistor equipment, good luck

: : Regards,

: : Gene

required replacement of ss100 switching transistor

: Hi Gene, Finding replacement semiconductors can be a real headache sometimes, though with diodes and transistors you can usually find good substitutes. I doubt if you'd have too much trouble finding a replacement for the detector with the same performance. Try NTE electronics at http://WWW.NTEINC.COM/ they specialize in replacement parts and often have eqivalents when no one else can supply. Their price is higher but that's better than not being able to get it at all and just reflects the problem of stocking rare parts that only sell in small quantities. Don Black.

: : I'm looking for a source of obselete semiconductors. I'm sure many of us have the problem, sooner or later.

: : I need to find a HPA 2034 diode. I've heard that it was made by Hewlett Packard. I doubt that, because as far as I know, they never made (or sourced) semiconductors. I need other semiconductors for a Model 18 Marantz. Anyone found any sources? It's gotten to the point where it's easy to fix tube equipment, but try vintage transistor equipment, good luck

: : Regards,

: : Gene

HI
I HAVE BEEN TRYING TO FIND A CROSS TO A HEWLETT-PACKARD 8447A AMPLIFIER. THE TRANSISTOR #
IS 1884-0012.CAN YOU HELP ME ? I WOULD SURE GREATFUL FOR THE HELP.
MALENFANT ELECTRONICS
THANK YOU MUCH