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Re: S-52 only works with lowered +15 V power supply
Hi Albert, these are the effects of work fatigue when I get home.... Here is the correct phrase: "The pot R90 (trig level) is almost fully CLOCKWISE (it's in the original position when I bought the
By unclebanjoman · #168886 ·
Re: Tek 603 - question on transistor heatsinking material
Page 5-48 of a widely accessible version of the yellow book says 342-0082-00 is alumina. Were it me, I's use silicone pads under all the transistors on that mounting bar. They're series pass elements,
By teamlarryohio · #168885 ·
Re: Tek 603 - question on transistor heatsinking material
We see cases of berylliosis (the beryllium lung disease) around here because there were a couple of aerospace manufacturers in the area. Beryllium is widely used in aerospace applications because of
By stevenhorii · #168884 ·
Re: S-52 only works with lowered +15 V power supply
Hi Max, Those pictures helped me a lot to understand what you previously said in words! Just for comparison I added an annotated picture to your album (and somewhat destroyed the order). You said R90
By Albert Otten · #168883 ·
tds-420a recapping (smell on startup)
hi, When I turn on the 420a, it give out -for just 30secs- a strong smell of rubber/car tire that disappear fast (no errors reported though); I think the caps are in need of a swap. Does anybody out
By chmax · #168881 ·
Re: Tek 603 - question on transistor heatsinking material
Beryllium ceramic is fascinating stuff. We all would use it a lot more but for the liability issues. It feels a lot like aluminum in that it draws the heat away from your skin very quickly, making it
By Chuck Harris <cfharris@...> · #168880 ·
Re: Tek 603 - question on transistor heatsinking material
There exists (existed?) a product called beryllia microspheres which can be used safely to increase the thermal conductivity of epoxy, silicone encapsulants, etc. They are also suitable for mixing
By SCMenasian · #168879 ·
Re: Tek 603 - question on transistor heatsinking material
I have some pink tinted alumina TO3 insulators as well as some blue tinted beryllia ones from the 1970's. The beryllia ones are much colder to the touch than the alumina ones. Bruce
By Bruce Griffiths · #168878 ·
Re: Tek 603 - question on transistor heatsinking material
That is correct. If I went with the mica, I can always use 2 pieces; I ordered some anyway, it's quite cheap at Digikey. I guess a bonus is that it's unlikely to break when clamped. --Toby
By toby@... · #168877 ·
Re: Tek 603 - question on transistor heatsinking material
Thanks as always, Chuck! These pads are under the low voltage (< 45V) TO-202 Darlingtons. Most likely I can reuse them. --Toby
By toby@... · #168876 ·
Re: Tek 603 - question on transistor heatsinking material
Beryllium and compounds have an unusual toxicity profile. Beryllium is not directly toxic as, say, arsenic is. However, how it harms you is to cause an intense allergic reaction. In the lungs, this
By stevenhorii · #168875 ·
Re: Looking for 7D02 Personality Modules
Hi Dennis, Have you ever used a software logic analyzer of this sort? I did at one of my customer's locations. They spent a gob of money on a set of software personality modules for their 1240 logic
By Chuck Harris <cfharris@...> · #168874 ·
Re: Tek 603 - question on transistor heatsinking material
It probably shattered when it was tightened. It will do that in a blink if the aluminum under it is not perfectly flat. I would goop it up, and put the pieces back into service. I you can't, or are
By Chuck Harris <cfharris@...> · #168873 ·
Re: Tek 603 - question on transistor heatsinking material
It has been reported that Tektronix used BeO ceramic all over the place. Some common examples are the heat sink insulators for the 5000 series H and V output transistors. They also used it as the heat
By Chuck Harris <cfharris@...> · #168872 ·
Re: Tektronix 2230
Hello Saroj, sorry to hear about the breakdown of your replaced parts... :-( Since you already confirmed that the scope worked when fed from a secondary power supply, and I assume it still does? If
By satbeginner · #168871 ·
Re: Tek 603 - question on transistor heatsinking material
Toby, It looks like there are several devices held in place with a common clamp bar. If that is the case, you need to match thickness fairly well, or perhaps use a thinner insulator like mica while
By John Gord · #168870 ·
Re: Tek 603 - question on transistor heatsinking material
Unless Walter at Sphere has the alumina, I might have to go with mica -- Digikey has some reasonably compatible rectangular pieces. https://www.digikey.ca/en/products/filter/thermal-pads-sheets/218
By toby@... · #168869 ·
Looking for 7D02 Personality Modules
I am looking for the following Personality Modules for the 7D02 Software Logic Analyzer Plugin. Please contact me off list at dennis at ridesoft dot com if you can help. It is very important that I
By Dennis Tillman W7pF · #168868 ·
Re: Tek 603 - question on transistor heatsinking material
That sounds probable. It sure is brittle, while this board was hard to remove, there would have been no major shocks, so I was surprised to see it shattered. Hope I can replace it, or is there a
By toby@... · #168867 ·
Re: Tek 603 - question on transistor heatsinking material
Toby, It looks like the part number is 342-0082-00, described as an insulator plate, 0.52" x 0.52" x 0.015", material: alumina (aluminum oxide). It is likely used with thermal compound added, --John
By John Gord · #168866 ·