Dear all, my 1S1 gave up. It looks at least one of my sampling diodes has died. Searching through the related messages I noticed most comments are pretty old, so I hope some new ideas might have been launched on getting alternatives for the original GaAs diodes, just assuming these are completely unobtainable.
Looked at the Agilent/KeySight site, they mention some ultra fast GHz diodes there but these go through a distributor and I suspect ut won't be easy to get 4 of these at reasonable cost (not knowing they would work either)
Any tips, suggestions?

Thanks so much, Leonard

I have not actually fixed one this way, but I would expect an HSMS-28xx Schottky to be a perfect replacement here. These are readily available.

Tom

Sent from my iThing, so please forgive the terseness and typos.

On Dec 9, 2020, at 14:26, "leonard scheepsma" <tubes.leonard@hetnet.nl> wrote:

Dear all, my 1S1 gave up. It looks at least one of my sampling diodes has died. Searching through the related messages I noticed most comments are pretty old, so I hope some new ideas might have been launched on getting alternatives for the original GaAs diodes, just assuming these are completely unobtainable.
Looked at the Agilent/KeySight site, they mention some ultra fast GHz diodes there but these go through a distributor and I suspect ut won't be easy to get 4 of these at reasonable cost (not knowing they would work either)
Any tips, suggestions?

Thanks so much, Leonard

On Dec 9, 2020, at 3:31 PM, Dave Wise <david_wise@phoenix.com> wrote:

I replaced my 1S1's four sampling diodes with four HSMS-8202 dual diodes, with each part wired to use the two diodes in series to increase the breakdown voltage and reduce the capacitance.
They are marked Obsolete at the major distributors, but Quest Components appears to have a few, as do MiniKits in Australia. There are about a dozen auctions at eBay.

Today I would use the Macom MA4E2054B1-287T which they list as a direct cross-ref. They are in stock at DigiKey and Mouser.
Or the Infineon BAT15, BAT17, or BAT62.

HTH,
Dave Wise

These are SOT-23. I made a little T-shaped "chip carrier" out of bare PCB material that fits in the original clips.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jim Ford via groups.io <james.ford=cox.net@groups.io>
Sent: Wednesday, December 09, 2020 2:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What alternatives?

Although discontinued by Avago/Broadcom, I'm sure. That's the way it
goes these days. They discontinued me and a whole lot of others as
well, as some of you are probably tired of hearing me say!

The HSMS-28XX and other former HP Semiconductor devices just don't have
the volume they once had, and the suits at Avago/Broadcom don't like
that, nor do their investors.

Jim Ford

------ Original Message ------
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: "TekScopes@groups.io" <TekScopes@groups.io>
Sent: 12/9/2020 2:31:43 PM
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What
alternatives?

I have not actually fixed one this way, but I would expect an HSMS-28xx Schottky to be a perfect replacement here. These are readily available.

Tom

Sent from my iThing, so please forgive the terseness and typos.

On Dec 9, 2020, at 14:26, "leonard scheepsma" <tubes.leonard@hetnet.nl> wrote:

Dear all, my 1S1 gave up. It looks at least one of my sampling diodes has died. Searching through the related messages I noticed most comments are pretty old, so I hope some new ideas might have been launched on getting alternatives for the original GaAs diodes, just assuming these are completely unobtainable.
Looked at the Agilent/KeySight site, they mention some ultra fast GHz diodes there but these go through a distributor and I suspect ut won't be easy to get 4 of these at reasonable cost (not knowing they would work either)
Any tips, suggestions?

Thanks so much, Leonard

On Dec 9, 2020, at 3:31 PM, Dave Wise <david_wise@phoenix.com> wrote:

I replaced my 1S1's four sampling diodes with four HSMS-8202 dual diodes, with each part wired to use the two diodes in series to increase the breakdown voltage and reduce the capacitance.
They are marked Obsolete at the major distributors, but Quest Components appears to have a few, as do MiniKits in Australia. There are about a dozen auctions at eBay.

Today I would use the Macom MA4E2054B1-287T which they list as a direct cross-ref.  They are in stock at DigiKey and Mouser.
Or the Infineon BAT15, BAT17, or BAT62.

HTH,
Dave Wise

These are SOT-23.  I made a little T-shaped "chip carrier" out of bare PCB material that fits in the original clips.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jim Ford via groups.io <james.ford=cox.net@groups.io>
Sent: Wednesday, December 09, 2020 2:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What alternatives?

Although discontinued by Avago/Broadcom, I'm sure.  That's the way it
goes these days.  They discontinued me and a whole lot of others as
well, as some of you are probably tired of hearing me say!

The HSMS-28XX and other former HP Semiconductor devices just don't have
the volume they once had, and the suits at Avago/Broadcom don't like
that, nor do their investors.

Jim Ford

------ Original Message ------
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: "TekScopes@groups.io" <TekScopes@groups.io>
Sent: 12/9/2020 2:31:43 PM
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What
alternatives?

I have not actually fixed one this way, but I would expect an HSMS-28xx Schottky to be a perfect replacement here. These are readily available.

Tom

Sent from my iThing, so please forgive the terseness and typos.

On Dec 9, 2020, at 14:26, "leonard scheepsma" <tubes.leonard@hetnet.nl> wrote:

Dear all, my 1S1 gave up. It looks at least one of my sampling diodes has died. Searching through the related messages I noticed most comments are pretty old, so I hope some new ideas might have been launched on getting alternatives for the original GaAs diodes, just assuming these are completely unobtainable.
Looked at the Agilent/KeySight site, they mention some ultra fast GHz diodes there but these go through a distributor and I suspect ut won't be easy to get 4 of these at reasonable cost (not knowing they would work either)
Any tips, suggestions?

Thanks so much, Leonard

On Dec 9, 2020, at 4:05 PM, Brian via groups.io <brianas1948=yahoo.co.uk@groups.io> wrote:

 Hi DaveI have also used HSMS8202 to repair S3A probes and have even made a replacement sampling sampling gate for an S6 sampling head . I can recommend them for the purpose , they have a higher reverse breakdown voltage than the 2825 I think .
regardsBrian

On Wednesday, 9 December 2020, 23:59:22 GMT, Tom Lee <tomlee@ee.stanford.edu> wrote:

Hi Dave,

I’ve used that very combination for 10GHz sampling bridges and it works very well. The rest of the 1S1 would be the performance limiter.

Less-capable diodes would work as well in this case, and would probably be more robust. As you and Jim Ford have noted, the HSMS diodes are now officially obsolete, so the usual distributors no longer stock them. But I see that Dan’s Small Parts and Kits has HSMS-2825 (dual diodes) at 10 for a buck. Hard to beat that. Buy a bunch more stuff to get your shipping dollar’s worth. And as with all of Dan’s deliveries, you’ll also get a large amount of tobacco smoke as a free bonus. Open your package outdoors if you’re sensitive. I’m only partly joking.

— Cheers,
Tom

Sent from my iThing, so please forgive typos and brevity.

On Dec 9, 2020, at 3:31 PM, Dave Wise <david_wise@phoenix.com> wrote:

I replaced my 1S1's four sampling diodes with four HSMS-8202 dual diodes, with each part wired to use the two diodes in series to increase the breakdown voltage and reduce the capacitance.
They are marked Obsolete at the major distributors, but Quest Components appears to have a few, as do MiniKits in Australia. There are about a dozen auctions at eBay.

Today I would use the Macom MA4E2054B1-287T which they list as a direct cross-ref. They are in stock at DigiKey and Mouser.
Or the Infineon BAT15, BAT17, or BAT62.

HTH,
Dave Wise

These are SOT-23. I made a little T-shaped "chip carrier" out of bare PCB material that fits in the original clips.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jim Ford via groups.io <james.ford=cox.net@groups.io>
Sent: Wednesday, December 09, 2020 2:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What alternatives?

Although discontinued by Avago/Broadcom, I'm sure. That's the way it
goes these days. They discontinued me and a whole lot of others as
well, as some of you are probably tired of hearing me say!

The HSMS-28XX and other former HP Semiconductor devices just don't have
the volume they once had, and the suits at Avago/Broadcom don't like
that, nor do their investors.

Jim Ford

------ Original Message ------
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: "TekScopes@groups.io" <TekScopes@groups.io>
Sent: 12/9/2020 2:31:43 PM
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What
alternatives?

I have not actually fixed one this way, but I would expect an HSMS-28xx Schottky to be a perfect replacement here. These are readily available.

Tom

Sent from my iThing, so please forgive the terseness and typos.

On Dec 9, 2020, at 14:26, "leonard scheepsma" <tubes.leonard@hetnet.nl> wrote:

Dear all, my 1S1 gave up. It looks at least one of my sampling diodes has died. Searching through the related messages I noticed most comments are pretty old, so I hope some new ideas might have been launched on getting alternatives for the original GaAs diodes, just assuming these are completely unobtainable.
Looked at the Agilent/KeySight site, they mention some ultra fast GHz diodes there but these go through a distributor and I suspect ut won't be easy to get 4 of these at reasonable cost (not knowing they would work either)
Any tips, suggestions?

Thanks so much, Leonard

On Dec 9, 2020, at 4:05 PM, Brian via groups.io <brianas1948=yahoo.co.uk@groups.io> wrote:

 Hi DaveI have also used HSMS8202 to repair S3A probes and have even made a replacement sampling sampling gate for an S6 sampling head . I can recommend them for the purpose , they have a higher reverse breakdown voltage than the 2825 I think .
regardsBrian

    On Wednesday, 9 December 2020, 23:59:22 GMT, Tom Lee <tomlee@ee.stanford.edu> wrote:

Hi Dave,

I’ve used that very combination for 10GHz sampling bridges and it works very well. The rest of the 1S1 would be the performance limiter.

Less-capable diodes would work as well in this case, and would probably be more robust. As you and Jim Ford have noted, the HSMS diodes are now officially obsolete, so the usual distributors no longer stock them. But I see that Dan’s Small Parts and Kits has HSMS-2825 (dual diodes) at 10 for a buck. Hard to beat that. Buy a bunch more stuff to get your shipping dollar’s worth. And as with all of Dan’s deliveries, you’ll also get a large amount of tobacco smoke as a free bonus. Open your package outdoors if you’re sensitive. I’m only partly joking.

— Cheers,
Tom

Sent from my iThing, so please forgive typos and brevity.

On Dec 9, 2020, at 3:31 PM, Dave Wise <david_wise@phoenix.com> wrote:

I replaced my 1S1's four sampling diodes with four HSMS-8202 dual diodes, with each part wired to use the two diodes in series to increase the breakdown voltage and reduce the capacitance.
They are marked Obsolete at the major distributors, but Quest Components appears to have a few, as do MiniKits in Australia. There are about a dozen auctions at eBay.

Today I would use the Macom MA4E2054B1-287T which they list as a direct cross-ref.  They are in stock at DigiKey and Mouser.
Or the Infineon BAT15, BAT17, or BAT62.

HTH,
Dave Wise

These are SOT-23.  I made a little T-shaped "chip carrier" out of bare PCB material that fits in the original clips.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jim Ford via groups.io <james.ford=cox.net@groups.io>
Sent: Wednesday, December 09, 2020 2:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What alternatives?

Although discontinued by Avago/Broadcom, I'm sure.  That's the way it
goes these days.  They discontinued me and a whole lot of others as
well, as some of you are probably tired of hearing me say!

The HSMS-28XX and other former HP Semiconductor devices just don't have
the volume they once had, and the suits at Avago/Broadcom don't like
that, nor do their investors.

Jim Ford

------ Original Message ------
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: "TekScopes@groups.io" <TekScopes@groups.io>
Sent: 12/9/2020 2:31:43 PM
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What
alternatives?

I have not actually fixed one this way, but I would expect an HSMS-28xx Schottky to be a perfect replacement here. These are readily available.

Tom

Sent from my iThing, so please forgive the terseness and typos.

On Dec 9, 2020, at 14:26, "leonard scheepsma" <tubes.leonard@hetnet.nl> wrote:

Dear all, my 1S1 gave up. It looks at least one of my sampling diodes has died. Searching through the related messages I noticed most comments are pretty old, so I hope some new ideas might have been launched on getting alternatives for the original GaAs diodes, just assuming these are completely unobtainable.
Looked at the Agilent/KeySight site, they mention some ultra fast GHz diodes there but these go through a distributor and I suspect ut won't be easy to get 4 of these at reasonable cost (not knowing they would work either)
Any tips, suggestions?

Thanks so much, Leonard

Hi Dave,

I’ve used that very combination for 10GHz sampling bridges and it works very well. The rest of the 1S1 would be the performance limiter.

Less-capable diodes would work as well in this case, and would probably be more robust. As you and Jim Ford have noted, the HSMS diodes are now officially obsolete, so the usual distributors no longer stock them. But I see that Dan’s Small Parts and Kits has HSMS-2825 (dual diodes) at 10 for a buck. Hard to beat that. Buy a bunch more stuff to get your shipping dollar’s worth. And as with all of Dan’s deliveries, you’ll also get a large amount of tobacco smoke as a free bonus. Open your package outdoors if you’re sensitive. I’m only partly joking.

— Cheers,
Tom

Sent from my iThing, so please forgive typos and brevity.

On Dec 9, 2020, at 3:31 PM, Dave Wise <david_wise@phoenix.com> wrote:

I replaced my 1S1's four sampling diodes with four HSMS-8202 dual diodes, with each part wired to use the two diodes in series to increase the breakdown voltage and reduce the capacitance.
They are marked Obsolete at the major distributors, but Quest Components appears to have a few, as do MiniKits in Australia. There are about a dozen auctions at eBay.

Today I would use the Macom MA4E2054B1-287T which they list as a direct cross-ref. They are in stock at DigiKey and Mouser.
Or the Infineon BAT15, BAT17, or BAT62.

HTH,
Dave Wise

These are SOT-23. I made a little T-shaped "chip carrier" out of bare PCB material that fits in the original clips.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jim Ford via groups.io <james.ford=cox.net@groups.io>
Sent: Wednesday, December 09, 2020 2:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What alternatives?

Although discontinued by Avago/Broadcom, I'm sure. That's the way it
goes these days. They discontinued me and a whole lot of others as
well, as some of you are probably tired of hearing me say!

The HSMS-28XX and other former HP Semiconductor devices just don't have
the volume they once had, and the suits at Avago/Broadcom don't like
that, nor do their investors.

Jim Ford

------ Original Message ------
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: "TekScopes@groups.io" <TekScopes@groups.io>
Sent: 12/9/2020 2:31:43 PM
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What
alternatives?

I have not actually fixed one this way, but I would expect an HSMS-28xx Schottky to be a perfect replacement here. These are readily available.

Tom

Sent from my iThing, so please forgive the terseness and typos.

On Dec 9, 2020, at 14:26, "leonard scheepsma" <tubes.leonard@hetnet.nl> wrote:

Dear all, my 1S1 gave up. It looks at least one of my sampling diodes has died. Searching through the related messages I noticed most comments are pretty old, so I hope some new ideas might have been launched on getting alternatives for the original GaAs diodes, just assuming these are completely unobtainable.
Looked at the Agilent/KeySight site, they mention some ultra fast GHz diodes there but these go through a distributor and I suspect ut won't be easy to get 4 of these at reasonable cost (not knowing they would work either)
Any tips, suggestions?

Thanks so much, Leonard

Hi Tom
sorry about that I must be remembering one of the other devices from that series . I have not had any fail on me yet and it was several years ago that I made both of those repairs , naturally I took ESD precautions while assembling everything .
regards
Brian
On Thursday, 10 December 2020, 00:15:23 GMT, Tom Lee <tomlee@ee.stanford.edu> wrote:
Nope. The 8202 is a VERY delicate beast (typical trade off between robustness and speed here). It is easily damaged by ESD during handling. It’s a 4V breakdown device, as compared to a 2825’s much greater 15V breakdown.

Sent from my iThing, so please forgive typos and brevity.

On Dec 9, 2020, at 4:05 PM, Brian via groups.io <brianas1948=yahoo.co.uk@groups.io> wrote:

 Hi DaveI have also used HSMS8202 to repair S3A probes and have even made a replacement sampling sampling gate for an S6 sampling head . I can recommend them for the purpose , they have a higher reverse breakdown voltage than the 2825 I think .
regardsBrian

    On Wednesday, 9 December 2020, 23:59:22 GMT, Tom Lee <tomlee@ee.stanford.edu> wrote:

Hi Dave,

I’ve used that very combination for 10GHz sampling bridges and it works very well. The rest of the 1S1 would be the performance limiter.

Less-capable diodes would work as well in this case, and would probably be more robust. As you and Jim Ford have noted, the HSMS diodes are now officially obsolete, so the usual distributors no longer stock them. But I see that Dan’s Small Parts and Kits has HSMS-2825 (dual diodes) at 10 for a buck. Hard to beat that. Buy a bunch more stuff to get your shipping dollar’s worth. And as with all of Dan’s deliveries, you’ll also get a large amount of tobacco smoke as a free bonus. Open your package outdoors if you’re sensitive. I’m only partly joking.

— Cheers,
Tom

Sent from my iThing, so please forgive typos and brevity.

On Dec 9, 2020, at 3:31 PM, Dave Wise <david_wise@phoenix.com> wrote:

I replaced my 1S1's four sampling diodes with four HSMS-8202 dual diodes, with each part wired to use the two diodes in series to increase the breakdown voltage and reduce the capacitance.
They are marked Obsolete at the major distributors, but Quest Components appears to have a few, as do MiniKits in Australia. There are about a dozen auctions at eBay.

Today I would use the Macom MA4E2054B1-287T which they list as a direct cross-ref.  They are in stock at DigiKey and Mouser.
Or the Infineon BAT15, BAT17, or BAT62.

HTH,
Dave Wise

These are SOT-23.  I made a little T-shaped "chip carrier" out of bare PCB material that fits in the original clips.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jim Ford via groups.io <james.ford=cox.net@groups.io>
Sent: Wednesday, December 09, 2020 2:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What alternatives?

Although discontinued by Avago/Broadcom, I'm sure.  That's the way it
goes these days.  They discontinued me and a whole lot of others as
well, as some of you are probably tired of hearing me say!

The HSMS-28XX and other former HP Semiconductor devices just don't have
the volume they once had, and the suits at Avago/Broadcom don't like
that, nor do their investors.

Jim Ford

------ Original Message ------
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: "TekScopes@groups.io" <TekScopes@groups.io>
Sent: 12/9/2020 2:31:43 PM
Subject: Re: [TekScopes] 1S1 sampling bridge GaAs diodes: What
alternatives?

I have not actually fixed one this way, but I would expect an HSMS-28xx Schottky to be a perfect replacement here. These are readily available.

Tom

Sent from my iThing, so please forgive the terseness and typos.

On Dec 9, 2020, at 14:26, "leonard scheepsma" <tubes.leonard@hetnet.nl> wrote:

Dear all, my 1S1 gave up. It looks at least one of my sampling diodes has died. Searching through the related messages I noticed most comments are pretty old, so I hope some new ideas might have been launched on getting alternatives for the original GaAs diodes, just assuming these are completely unobtainable.
Looked at the Agilent/KeySight site, they mention some ultra fast GHz diodes there but these go through a distributor and I suspect ut won't be easy to get 4 of these at reasonable cost (not knowing they would work either)
Any tips, suggestions?

Thanks so much, Leonard

Could a simple 1N5711 be jammed in there for that job?

I would think so, and it's in a package that is easy to handle.

I love the 1N5711. I've replaced several of the GaAs diodes in the 1S1 memory circuit with 1N5711s and it works fine.