[fazer]

Looking for this dual Jfet N channel used in the front end of a Tektronix O Scope

Tek part#151-1049-00   generic  part number is DN872. in a TO71 case with 6 leads. 

These are long gone probably but looking for a Data sheet on the DN872 to try and cross with a current available dual JFet Part part.

Anybody have a data sheet or cross part suggestion.

[scott2000]

Looking up the part and came across this place?

http://www.culverequipment.com/Tektronix_ICs.html

[fazer]

Thanks Scott !    I see they have some.  I sent a request form to them.   I looked at sites that came up in a google search and the 2 site’s were sold out.   Hope they come through. Thanks again Buddy.

[Dualflip]

Looking up the part and came across this place?

http://www.culverequipment.com/Tektronix_ICs.html

That webpage looks like it was made by a High School student learning to code HTML.

[shabtek]

That webpage looks like it was made by a High School student learning to code HTML.

reminds me of web browsing in the good old days

[fazer]

That webpage looks like it was made by a High School student learning to code HTML.

Looks like a student from the 1990s.

They sell some weird stuff but the tek parts are all I care about.  Hope their still in business.  I sent a request form and have not heard back.   

[scott2000]

Wonder if they're on lockdown..not sure how that area of CA is.There's a phone number iirc...

Yeah that site..lol


I'm sure the physical business is just as exciting...

[fazer]

I called the number and their phone system routes you to sales and the sales mailbox is full so no message to leave.   I'll try calling  again but if you dial 0 you get the message recycling.   

If I could get a Data sheet on a DN872 dual fet, I could match to something that is available but thats the problem with old equipment.  I have 1 channel working and plan to go through the scope since I found a service manual.   I've got $40 buck in this one so far.   

Its time to get a digital scope but I don't need Hi bandwidth for mostly servicing tube amps and some old console equipment.   I have a Fluke 97 handheld (1990's)that is useful but that lagging non realtime feel of it drives me nuts sometimes.   My old Hitachi has a HV problem and the display is nonlinear but has repaired a boatload of audio equipment over the years.   

[fazer]

Well got an email back and the drawer was empty of the dual FETs.  So will have to try to figure a sub but no data on the DN872.  Oh well!   

[JohnRoberts]

do they even describe wether they are N ch or P ch? I/m guessing n ch.

There are dual N ch jfets in other packages.

Good luck


JR

[fazer]

It’s N channel and there are other duals that I’m sure could be used.   The DN872 info is unavailable from my searches so time to analyze some other candidates.   I’ll get back to it .   Working in post production has made my audio chops strong but my electronic skills are weak.   I just need to put some time into figuring some substitute for the front end diff amp.   

[JohnRoberts]

Digikey has something like 30 but most are in SMD package that may be difficult to cobble in. Only one available in a metal can and that puppy is expensive ($11) and might not work... The smd are <$1.

https://www.digikey.com/products/en/discrete-semiconductor-products/transistors-jfets/288?k=dual+jfet&k=&pkeyword=dual+jfet&sv=0&pv606=121938&sf=0&FV=-8%7C288&quantity=&ColumnSort=0&page=1&pageSize=25

The SMD duals look like they only have 5 leads with source common to both JFETs. This should work for a long tail pair topology. The metal can brings out the two sources independently.

JR

[rackmonkey]

Is this for a 400-series scope, Fazer? Is it the dual JFET on the vertical input? Give us some details on the model and it’ll make it easier to help you.

[fazer]

Is this for a 400-series scope, Fazer? Is it the dual JFET on the vertical input? Give us some details on the model and it’ll make it easier to help you.

This is a 5103N-15 Scope with 500 series Modules.   The 5A18 is the exact plugIn module  and Ive included a schematic.   Q201A/B is the dual Fet used.    Its a low bandwidth scope but fine for Tube Gear with a probe 10/1 100/1.

[fazer]

this is theory of op for input.
 

[rackmonkey]

I can tell you that the "DN" prefix indicates a Siliconix part. Your best bet for finding data on it is in an old Siliconix Small Signal FET Data Book. I have checked the January 1986 edition and it was probably obsolete by then, although other DN series dual JFETs are in there. I haven't yet scoured my storage or the Interwebs thoroughly for an older edition, but I could swear I have one from the late 70s here somewhere. I'll see if I can dig it up.

[fazer]

Thanks Rackmonkey.  Yes a Siliconix part.  I'll keep searching for parameters book.  It exist somewhere.    it is a 70's era scope.   

[fazer]

There is a 1977 Siliconix  FET Data book.  have not found on the web but it seems like it would have information on the DN part if its anywhere to be found.

[rackmonkey]

I’ve found the 1977 National Semiconductor FET book, but nothing from Siliconix for that year. But I think I may have a hard copy of one around here somewhere.

[fazer]

Found a copy of it on eBay. $20.   If you find your copy , it might have parameters for DN872 and would greatly appreciate a copy.  Of that data sheet.  Thanks for looking. And I do have a copy of National 1977 and 1986 siliconix book but as you have said no info in the 1986 book.   

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