Steve, I don't think I have any Telefunken tubes.
Amperex, Mullard and a variety of US brands but
no German tubes.
I do have (I used to work for Tektronix as a FE) a spare dual gun
CRT for my 565 scope pictured and discussed in this article
http://www.antiqueradios.com/forums/viewtopic.php?f=8&t=200096
Jim Williams (brilliant designer at Linear Technology, now sadly deceased) swapped
me my spare Tek 6042 1mA-10A DC-50MHz current waveform probe for a Tek 547.
I've got two more old Tek beauty's and plug-ins.
BTW, Jim did all his app notes with old Tek tube scopes. His app notes are
quite humorous, especially the ones on switching
regulators as that's when he was caring for their new baby.
At the end of each app is a row of baby bottles, the number
of bottles represented how long it took Jim to do the app note.
Speaking of vacuum tubes, would love to have one of these...
http://item.mobileweb.ebay.com/viewitem?itemId=170403438886
Burned in for 5000 hours, not one of them ever failed in the life of TAT-1. The cable was never recovered from the sea bed (after many attempts) when they cut over to the next cable that could carry many more circuits. Western Electric was an incredibly good design/mfg facility.
I do have very rare tube, a Burroughs decade
counter tube in its original carton. It has a circular magnet wrapped around
and cemented to it and inside are ten stages of what look
like neon bulbs. It's a shift register! Imagine a Burroughs computer
full of these things!
I remember a very old HP frequency
counters where the digits were neon bulbs behind
numbers 0-9 and the last two digits were so slow they
used small electromechanical meters with their scales
marked 0-9 ! I've been looking for a picture of it
but not knowing the model # haven't found it.
From vacuum tubes to SMT in a lifetime..,
Could we ever have imagined it?
Bob
On Feb 16, 2013, at 8:09 AM, Steven Creswick <[log in to unmask]> wrote:
> Speaking of cherished items, anyone having a working Telefunken VF-14 metal
> can tube has a prize!
>
> Steve C
>
> -----Original Message-----
> From: Bob Landman [mailto:[log in to unmask]]
> Sent: Saturday, February 16, 2013 7:48 AM
> To: TechNet E-Mail Forum; Steven Creswick
> Subject: Re: [TN] AR/UR Conformal coatings - NTC
>
> Brian,
>
> Of course I know what a pentode is and also can still recall the base wiring
> of most vacuum tubes (valves to you Brits). 2 & 7 are the filaments. My
> scope was a Heathkit with a 5UP1 (I've still got it in the cellar). I still
> have quite a collection of tubes including KT66 and KT88 pentode output
> tubes. Amperex ECC83 & ECC88 as well.
> Also recal that the last number of a CRT is the phosphor type (7 is blue
> with a yellow afterglow - best for slow signals like EKG).
>
> Speaking of insulating coatings I still have a bottle of corona dope and
> also glyptal. "Glyp it then ship it" we used to say. Fish paper insulation
> instead of craft paper. Litz wire....
>
> Oh those were the days....
>
> Bob Landman
>
> Sent from my iPhone
>
> On Feb 16, 2013, at 7:25 AM, Steven Creswick <[log in to unmask]>
> wrote:
>
>> Brian,
>>
>> Just like a fine wine, getting better!
>>
>> Steve C
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
>> Sent: Saturday, February 16, 2013 2:17 AM
>> To: [log in to unmask]
>> Subject: Re: [TN] AR/UR Conformal coatings
>>
>> Not for electrical purposes AFAIK. It is still used for French
>> polishing of wood but even that is largely displaced by synthetic
>> resins, except for valuable furniture. Talking of which, I'd be
>> curious to know the composition of the lacquer that the Japanese use
>> for wood (tableware and decorative items). I know it is tapped from
>> trees in a similar way to latex. (Shellac comes from an insect.)
>>
>> I think I made the oscilloscope, for my own amateur use (I was a ham)
>> in
>> 1948 or 49. I was still a Uni student at the time (graduated 1951, when I
> started military service). For the anecdote, I used a Puckle timebase, with
> a pentode used as a constant current source to charge the capacitors, giving
> a good linearity with sweep times from 1 sec to 10 microsecs. Bet that takes
> you back in time. How many here even know what a pentode is?
>>
>> Another insulation I used was paraffin wax. I wound the high voltage
> transformer by hand, using a quite fragile 36 SWG wire for the secondary,
> with thin kraft paper for interleaving between the layers. It took me
> several evenings. When it was finished and the laminations inserted, I
> impregnated the lot in hot wax for several hours, hoping the paper would
> absorb it. It lasted a couple of years before there was a flashover between
> the HT winding and the electrostatic screen between the primary and
> secondary windings!
>>
>> I'll be 81 in a couple of months (I'm now like a kid, saying he is nearly
> six!!! :-) ) Must be what they mean by 'second childhood'!
>>
>> Brian
>>
>> On 16/02/2013 02:08, Inge Hernefjord wrote:
>>> Is shellac still used? / Inge
>>> PS. U worked 1940!!! How old are you, man??? I thought some 70+ but
>>> you must be 70+++
>>>
>>> On 16 February 2013 00:41, Brian Ellis <[log in to unmask]
>>> <mailto:[log in to unmask]>> wrote:
>>>
>>> Graham
>>>
>>> I used shellac/ethanol in the 1940s for the anode voltage (~1.8 kV)
>>> assembly for an oscilloscope I built using a 3BP1 war surplus CRT.
>>> No, I didn't clean first, but remember this was tag-to-tag wiring,
>>> not PCB.
>>>
>>> Between then and acrylics, I used a phenol-formaldehyde formulation.
>>>
>>> Brian
>>>
>>>
>>> On 16/02/2013 00:04, Graham Naisbitt wrote:
>>>
>>> Hello everybody - IR Here!
>>>
>>> Question1 - Adhesion
>>>
>>> IMHO the problem is often derived from the presence of
>>> surfactants that have not been correctly controlled in earlier
>>> processes. "Correctly controlled" I acknowledge is an ambiguous
>>> term, but you need to go back to each process step and ensure
>>> that the process has been properly carried out: Solder resist -
>>> soldering processes - masking processes etc..
>>>
>>> That said, the fact is that certain acrylic based coatings
>>> exhibit poor adhesion and one solution to this is to bake the
>>> assembly at around 80DegC for 4 to 8 hours and often this issue
>>> is ameliorated.
>>>
>>> Question 2 - What are the best AR and UR coatings asked by
>>> Michael Strong of MG Chemicals .a competitor to HumiSeal et al
>>> so I need to be careful, and please don't complain if this seems
>>> too commercial, but since several of you asked...
>>>
>>> OK. First up, 1A33 was, to my knowledge - that is bound to be
>>> proved wrong - one of the very first single part urethanes
>>> rendering the coating process far easier and with less material
>>> waste compared to 2 part formulations. Also, it was TDI free.
>>>
>>> As for the subject of curing, I would prefer to see the
>>> following terms employed in the IPC-CC-830 Standard: Stage 1 =
>>> Tack Free; Stage 2 = Dry (for handling) and Stage 3 = Full cure.
>>>
>>> The product will reach Tack Free in around 30 to 45 minutes,
>>> ambient. Dry in 2 to 4 hours, ambient and full cure either, 12
>>> hour bake at 80C or it will need to be exposed to 80C to
>>> initiate the full cure. It is the oil used in the product that
>>> turns an amber colour with heat, but that's the trade-off for a
>>> more user-friendly product.
>>>
>>> 1B31 was first introduced in or around 1975. A single-part
>>> acrylic, its main advantage is total repairability. Tack-Free =
>>> 10 to 15 minutes ambient; Dry in around 1 hour, ambient and full
>>> cure in about 24 hours, ambient.
>>>
>>> In around 1979/80, believing that 1B31 represented a major
>>> protection breakthrough, I recall being properly admonished by a
>>> senior manager at GEC Avionics in Rochester - ENGLAND - that the
>>> first conformal coating ever used was a type of Shellac used on
>>> the very early radars fitted to various RAF aircraft from around
>>> 1942.
>>>
>>> So, 1B31 effectively grandfathers ALL acrylic coatings. 1A33
>>> replaced most 2 part urethane formulations. Rather similar to
>>> the story of Rolls Royce, they just make a better product and
>>> they have a terrific pedigree. They have many worthy competitors.
>>>
>>> BTW techies, for those who don't know, I essentially ceased
>>> involvement with HumiSeal when I sold my business to them in 2005.
>>>
>>> Graham Naisbitt
>>>
>>>
>>> On 15 Feb 2013, at 16:54, Inge Hernefjord
>>> <[log in to unmask] <mailto:[log in to unmask]>> wrote:
>>>
>>> Where is Coating Nosebite....Nicebitt...hm....__Naisbitt ?
>>>
>>> On 15 February 2013 08:14, Michael Strong
>>> <[log in to unmask]
>>> <mailto:[log in to unmask]>>wrote:
>>>
>>> Just a general query on what are the best AR and UR
>>> solvent-based coatings
>>> available. I know Humiseal and Elantas are big players
>>> but I'd like to
>>> know
>>> what are their big products and why.
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