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I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
TIA
B
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Based on the Tektronix parts catalog, I suspect the 151-0133-00 or 2N3251 transistors were graded for an Icbo (collector to base leakage current) of 10nA or less although the test conditions are unclear. Some of the other grades of the same transistor are shown as 10 times worse. I would be very surprised if a 2N2907, 2N3906, or 2N4403 did not make a great substitute. They are almost exact matches. On Wed, 16 Jan 2013 01:38:00 -0000, "andersen_bill@..." <andersen_bill@...> wrote: I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
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Oh, and the 2N3251A transistors should work fine as well. The A versions are graded for higher voltage and higher gain. I suspect the leakage will only matter for Q114. The 2N3906 or 2N4403 would be cheaper unless you found a really good deal. On Tue, 15 Jan 2013 22:17:45 -0600, David <davidwhess@...> wrote: Based on the Tektronix parts catalog, I suspect the 151-0133-00 or
2N3251 transistors were graded for an Icbo (collector to base leakage
current) of 10nA or less although the test conditions are unclear.
Some of the other grades of the same transistor are shown as 10 times
worse.
I would be very surprised if a 2N2907, 2N3906, or 2N4403 did not make
a great substitute. They are almost exact matches.
On Wed, 16 Jan 2013 01:38:00 -0000, "andersen_bill@..."
<andersen_bill@...> wrote:
I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
|
Thanks for the replies.
The 184 is up and running. Who ever had been into it turned it into a real mess 5 other transistors on the countdown board had been replaced with the wrong parts.
Everthing else in the unit looks original with no repairs to any of the boards.
The only thing I notice is the 1us marker is slightly higher in amplitude versus the other markers. ~ 1.95v vs `1.5v on the other markers.
I am thinking the 3251 A vs a regular 3251 in Q134 is the cause?
Thanks again.
B
toggle quoted message
Show quoted text
--- In TekScopes@..., "andersen_bill@..." wrote:
I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
TIA
B
|
That could be but there is some variation in marker height between different output settings anyway. On Thu, 17 Jan 2013 08:40:35 -0000, "andersen_bill@..." <andersen_bill@...> wrote:
Thanks for the replies.
The 184 is up and running. Who ever had been into it turned it into a real mess 5 other transistors on the countdown board had been replaced with the wrong parts.
Everthing else in the unit looks original with no repairs to any of the boards.
The only thing I notice is the 1us marker is slightly higher in amplitude versus the other markers. ~ 1.95v vs `1.5v on the other markers.
I am thinking the 3251 A vs a regular 3251 in Q134 is the cause?
Thanks again.
B
--- In TekScopes@..., "andersen_bill@..." wrote:
I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
TIA
B
|
I have another transistor question on this one.
The unit is up and running as stated and looks to be within specs.
I was checking the rest of the transistors on the countdown board and their are quit a few of the same type listed in the SM. Q193, for example. The service manual states for these, "replaceable by 2N198".
All of the ones in my unit are marked 2N3605. They appear to untouched and original.
Is this correct? Is their a more available replacemnt for this type?
Maybe with better performance?
Thanks
toggle quoted message
Show quoted text
--- In TekScopes@..., "andersen_bill@..." wrote:
I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
TIA
B
|
Now that I think about that is the 2N198 missing a digit?
They are all listed in the SM as 2N198, semms like the last digit is missing?
toggle quoted message
Show quoted text
--- In TekScopes@..., "andersen_bill@..." wrote:
I have another transistor question on this one.
The unit is up and running as stated and looks to be within specs.
I was checking the rest of the transistors on the countdown board and their are quit a few of the same type listed in the SM. Q193, for example. The service manual states for these, "replaceable by 2N198".
All of the ones in my unit are marked 2N3605. They appear to untouched and original.
Is this correct? Is their a more available replacemnt for this type?
Maybe with better performance?
Thanks
--- In TekScopes@..., "andersen_bill@" wrote:
I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
TIA
B
|
It is 2N918 and not 2N198. The 2N918 was a very common early VHF transistor. My 184 has 2N3605 transistors as well. The 2N918 is: 900 MHz @ 4 mA 30 Vcbo 15 Vceo 50 mA From the Tektronix parts book the 2N3605 is: 300 MHz @ 10mA 18 Vcbo 14 Vceo 200 mA The ubiquitous and inexpensive 2N2222, 2N3904, and 2N4401 should all work as replacements. On Sun, 20 Jan 2013 21:56:17 -0000, "andersen_bill@..." <andersen_bill@...> wrote: Now that I think about that is the 2N198 missing a digit?
They are all listed in the SM as 2N198, semms like the last digit is missing?
--- In TekScopes@..., "andersen_bill@..." wrote:
I have another transistor question on this one.
The unit is up and running as stated and looks to be within specs.
I was checking the rest of the transistors on the countdown board and their are quit a few of the same type listed in the SM. Q193, for example. The service manual states for these, "replaceable by 2N198".
All of the ones in my unit are marked 2N3605. They appear to untouched and original.
Is this correct? Is their a more available replacemnt for this type?
Maybe with better performance?
Thanks
|
That was my typo on the 2N918.
Of the 3 you list is one offer any better performance?
2N2222, 2N3904, and 2N4401
Thanks
toggle quoted message
Show quoted text
--- In TekScopes@..., David wrote:
It is 2N918 and not 2N198. The 2N918 was a very common early VHF
transistor. My 184 has 2N3605 transistors as well.
The 2N918 is:
900 MHz @ 4 mA
30 Vcbo 15 Vceo 50 mA
From the Tektronix parts book the 2N3605 is:
300 MHz @ 10mA
18 Vcbo 14 Vceo 200 mA
The ubiquitous and inexpensive 2N2222, 2N3904, and 2N4401 should all
work as replacements.
On Sun, 20 Jan 2013 21:56:17 -0000, "andersen_bill@..."
wrote:
Now that I think about that is the 2N198 missing a digit?
They are all listed in the SM as 2N198, semms like the last digit is missing?
--- In TekScopes@..., "andersen_bill@" wrote:
I have another transistor question on this one.
The unit is up and running as stated and looks to be within specs.
I was checking the rest of the transistors on the countdown board and their are quit a few of the same type listed in the SM. Q193, for example. The service manual states for these, "replaceable by 2N198".
All of the ones in my unit are marked 2N3605. They appear to untouched and original.
Is this correct? Is their a more available replacemnt for this type?
Maybe with better performance?
Thanks
|
No, not really. The 2N2222 has a higher power rating than the others and the 2N4401 has a higher current rating than the 2N3904 but none of that will matter in this application. As far as performance, what could be improved? It is a time mark generator. I would not replace the transistors unless I was fixing a problem or some had already gone bad presumably because of age. The 2N3904 is probably the best choice and the least expensive. On Sun, 20 Jan 2013 23:02:12 -0000, "andersen_bill@..." <andersen_bill@...> wrote: That was my typo on the 2N918.
Of the 3 you list is one offer any better performance?
2N2222, 2N3904, and 2N4401
Thanks
--- In TekScopes@..., David wrote:
It is 2N918 and not 2N198. The 2N918 was a very common early VHF
transistor. My 184 has 2N3605 transistors as well.
The 2N918 is:
900 MHz @ 4 mA
30 Vcbo 15 Vceo 50 mA
From the Tektronix parts book the 2N3605 is:
300 MHz @ 10mA
18 Vcbo 14 Vceo 200 mA
The ubiquitous and inexpensive 2N2222, 2N3904, and 2N4401 should all
work as replacements.
On Sun, 20 Jan 2013 21:56:17 -0000, "andersen_bill@..."
wrote:
Now that I think about that is the 2N198 missing a digit?
They are all listed in the SM as 2N198, semms like the last digit is missing?
--- In TekScopes@..., "andersen_bill@" wrote:
I have another transistor question on this one.
The unit is up and running as stated and looks to be within specs.
I was checking the rest of the transistors on the countdown board and their are quit a few of the same type listed in the SM. Q193, for example. The service manual states for these, "replaceable by 2N198".
All of the ones in my unit are marked 2N3605. They appear to untouched and original.
Is this correct? Is their a more available replacemnt for this type?
Maybe with better performance?
Thanks
|
Why all the subs?? 2n918's are still very available, and at least tow places have them under $2 each.?? Hard to rationalize subbing an available, cheapo transistor. ? Cheers, Taylor
|
Er, make that "two" places, and that doesn't include evilbay....
Cheers,
Taylor
Why all the subs? 2n918's are still very available, and at least tow places have them under $2 each. Hard to rationalize subbing an available, cheapo transistor.
Cheers,
Taylor
toggle quoted message
Show quoted text
--- In TekScopes@..., David wrote:
No, not really. The 2N2222 has a higher power rating than the others
and the 2N4401 has a higher current rating than the 2N3904 but none of
that will matter in this application.
As far as performance, what could be improved? It is a time mark
generator. I would not replace the transistors unless I was fixing a
problem or some had already gone bad presumably because of age.
The 2N3904 is probably the best choice and the least expensive.
On Sun, 20 Jan 2013 23:02:12 -0000, "andersen_bill@..."
wrote:
That was my typo on the 2N918.
Of the 3 you list is one offer any better performance?
2N2222, 2N3904, and 2N4401
Thanks
--- In TekScopes@..., David wrote:
It is 2N918 and not 2N198. The 2N918 was a very common early VHF
transistor. My 184 has 2N3605 transistors as well.
The 2N918 is:
900 MHz @ 4 mA
30 Vcbo 15 Vceo 50 mA
From the Tektronix parts book the 2N3605 is:
300 MHz @ 10mA
18 Vcbo 14 Vceo 200 mA
The ubiquitous and inexpensive 2N2222, 2N3904, and 2N4401 should all
work as replacements.
On Sun, 20 Jan 2013 21:56:17 -0000, "andersen_bill@"
wrote:
Now that I think about that is the 2N198 missing a digit?
They are all listed in the SM as 2N198, semms like the last digit is missing?
--- In TekScopes@..., "andersen_bill@" wrote:
I have another transistor question on this one.
The unit is up and running as stated and looks to be within specs.
I was checking the rest of the transistors on the countdown board and their are quit a few of the same type listed in the SM. Q193, for example. The service manual states for these, "replaceable by 2N198".
All of the ones in my unit are marked 2N3605. They appear to untouched and original.
Is this correct? Is their a more available replacemnt for this type?
Maybe with better performance?
Thanks
|
Thanks for the replies.
I picked up two of these at the same time. Both work but both had transistors removed.
I was looking for what were the most available parts for me that would work.
Thanks for the info.
toggle quoted message
Show quoted text
--- In TekScopes@..., Taylor Vandergrifft wrote:
Why all the subs?? 2n918's are still very available, and at least tow places have them under $2 each.?? Hard to rationalize subbing an available, cheapo transistor.
?
Cheers,
Taylor
|
Under $2 is not cheap for a jelly bean part. 2N3904 transistors are like 3.4 cents each. Even an MPSH11 which is a closer match to the 2N918 can be had for 8 cents each. Note that the above prices are for quantities of 100 since I never buy jelly bean parts like that in smaller quantities. On Sun, 20 Jan 2013 15:29:44 -0800 (PST), Taylor Vandergrifft <taylorvandy@...> wrote: Why all the subs?? 2n918's are still very available, and at least tow places have them under $2 each.?? Hard to rationalize subbing an available, cheapo transistor.
?
Cheers,
Taylor
|
OP was looking for a more available part - not a jelly bean part, whatever that is. If the original is still available, why the subs?
And no, most of us buy our parts in onesie-twosie fashion. What cheaper? 3 bucks for the originals, or $3.50/100 for a questionable sub?
Not trying to flame, just honoring the OP's intentions.
Cheers,
Taylor
toggle quoted message
Show quoted text
--- In TekScopes@..., David wrote:
Under $2 is not cheap for a jelly bean part. 2N3904 transistors are
like 3.4 cents each. Even an MPSH11 which is a closer match to the
2N918 can be had for 8 cents each.
Note that the above prices are for quantities of 100 since I never buy
jelly bean parts like that in smaller quantities.
On Sun, 20 Jan 2013 15:29:44 -0800 (PST), Taylor Vandergrifft
wrote:
Why all the subs?? 2n918's are still very available, and at least tow places have them under $2 each.?? Hard to rationalize subbing an available, cheapo transistor.
?
Cheers,
Taylor
|
The price would add up fast if he was looking to replace all 33 of the 2N3605/2N918 transistors in his 184. Most of the other small signal NPN transistors could be replaced as well. Jelly bean parts are produced by multiple manufacturers in large quantities and are almost always the most economical. New 2N918 transistors only come from Central Semiconductor and everything or just about everything they make is for the replacement market at a high premium although not as high as NTE. The original 2N3605 Tektronix used is not manufactured any more. The 2N3904 is hardly a questionable substitution for the original 2N3605. On Sun, 20 Jan 2013 23:55:47 -0000, "taylorvandy" <taylorvandy@...> wrote: OP was looking for a more available part - not a jelly bean part, whatever that is. If the original is still available, why the subs?
And no, most of us buy our parts in onesie-twosie fashion. What cheaper? 3 bucks for the originals, or $3.50/100 for a questionable sub?
Not trying to flame, just honoring the OP's intentions.
Cheers,
Taylor
--- In TekScopes@..., David wrote:
Under $2 is not cheap for a jelly bean part. 2N3904 transistors are
like 3.4 cents each. Even an MPSH11 which is a closer match to the
2N918 can be had for 8 cents each.
Note that the above prices are for quantities of 100 since I never buy
jelly bean parts like that in smaller quantities.
On Sun, 20 Jan 2013 15:29:44 -0800 (PST), Taylor Vandergrifft
wrote:
Why all the subs?? 2n918's are still very available, and at least tow places have them under $2 each.?? Hard to rationalize subbing an available, cheapo transistor.
?
Cheers,
Taylor
|
33 PN918's @ 0.33 each would be only 11 bucks, so why again would one substitute if an exact/jelly bean brother (PN918) part is available? Far too many times have I seen someone chase down a problem caused by a replacement "that should've worked"
Again, the OP asked "Is their (sic) a more available replacemnt for this type?
One google search, and one can see the originals are available, and are their plastic, TO-92 jelly bean relative.
Not to say that the 2n3904 wouldn't work....but the MPSH11 is obsolete, so that wouldn't help the OP with availabitlity issues.
No flame intended, just trying to help the OP with availability of the orignial parts.
Cheers,
Taylor
toggle quoted message
Show quoted text
--- In TekScopes@..., David wrote:
The price would add up fast if he was looking to replace all 33 of the
2N3605/2N918 transistors in his 184. Most of the other small signal
NPN transistors could be replaced as well.
Jelly bean parts are produced by multiple manufacturers in large
quantities and are almost always the most economical. New 2N918
transistors only come from Central Semiconductor and everything or
just about everything they make is for the replacement market at a
high premium although not as high as NTE. The original 2N3605
Tektronix used is not manufactured any more.
The 2N3904 is hardly a questionable substitution for the original
2N3605.
On Sun, 20 Jan 2013 23:55:47 -0000, "taylorvandy"
wrote:
OP was looking for a more available part - not a jelly bean part, whatever that is. If the original is still available, why the subs?
And no, most of us buy our parts in onesie-twosie fashion. What cheaper? 3 bucks for the originals, or $3.50/100 for a questionable sub?
Not trying to flame, just honoring the OP's intentions.
Cheers,
Taylor
--- In TekScopes@..., David wrote:
Under $2 is not cheap for a jelly bean part. 2N3904 transistors are
like 3.4 cents each. Even an MPSH11 which is a closer match to the
2N918 can be had for 8 cents each.
Note that the above prices are for quantities of 100 since I never buy
jelly bean parts like that in smaller quantities.
On Sun, 20 Jan 2013 15:29:44 -0800 (PST), Taylor Vandergrifft
wrote:
Why all the subs?? 2n918's are still very available, and at least tow places have them under $2 each.?? Hard to rationalize subbing an available, cheapo transistor.
?
Cheers,
Taylor
|
Well, I just ordered a bag of 100 2N3904's for $4.
Hopefully all goes well
B
toggle quoted message
Show quoted text
--- In TekScopes@..., "andersen_bill@..." wrote:
I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
TIA
B
|
I hope they're not counterfeit ....
You should test a few to see where Ft seems to be.
73 Jim N6ITQ?
From: "andersen_bill@..."
To: TekScopes@...
Sent: Sunday, January 20, 2013 7:04 PM
Subject: [TekScopes] Re: Type 184 Time Mark Generator Transistor Question
Well, I just ordered a bag of 100
2N3904's for $4. Hopefully all goes well B --- In TekScopes@..., "andersen_bill@..."? wrote: > > I am repairing a 184 that has had transistors removed from the countdown board. > > I am looking at; > > Q104 > > Q114 > > Q134 > > SM says "selected from 2N3251" > > I can get 2N3251A's local. > > I looked at the data sheets. Specs are close. Looks like the A has higher ratings. > > Does anyone know if they will work or do I need the non A part? > > TIA > > B > ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: ? ? <*> Your email settings: ? ? Individual Email | Traditional <*> To change settings online go to: ? ? ? ? (Yahoo! ID required) <*> To change settings via email: ? ? TekScopes-digest@... ? ? TekScopes-fullfeatured@...<*> To unsubscribe from this group, send an email to: ? ? TekScopes-unsubscribe@...<*> Your use of Yahoo! Groups is subject to: ? ?
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I am not sure why Tektronix listed the 2N918 as a replacement for the 2N3605 and I even went back and confirmed the specifications. My guess is that it had something to do with storage time, economics, pinout, or a mistake. The worst case problem I can think of is that the 2N3904 transistors oscillate due to higher current gain in some cases but I would consider that very unlikely if Tektronix was recommending the much faster 2N918 as a replacement. If it does happen, those little ferrite RFI suppression beads would fix it. I had to use them when I replaced relatively slow 2N3565s with 2N3904s in my DC505. The 2N3565s were dying of age. On Mon, 21 Jan 2013 01:04:11 -0000, "andersen_bill@..." <andersen_bill@...> wrote: Well, I just ordered a bag of 100 2N3904's for $4.
Hopefully all goes well
B
--- In TekScopes@..., "andersen_bill@..." wrote:
I am repairing a 184 that has had transistors removed from the countdown board.
I am looking at;
Q104
Q114
Q134
SM says "selected from 2N3251"
I can get 2N3251A's local.
I looked at the data sheets. Specs are close. Looks like the A has higher ratings.
Does anyone know if they will work or do I need the non A part?
TIA
B
|
David Hess