Brian I have a Dentron GLA1000B Amp that uses 4 6LQ6 tubes, 1.2kW out
pat
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Saturday, February 16, 2013 6:56 AM
To: [log in to unmask]
Subject: Re: [TN] AR/UR Conformal coatings - NTC
Sorry, Bob, the Osram/Mullard KT66/88 were not pentodes, they were beam tetrodes! :-) My first hifi ampli was a Williamson design I built with 6L6s instead of the KT66s. I originally tried 6V6s but I couldn't match them to the output trannie primary with a 15 ohm l/s load. Couldn't afford new KT66s as they cost 2 month's pocket money each, while 6Xxs and the three 12AX7s (equivalent to your ECC8xs) were war surplus for a few pence each. My ham Tx used 807s in the final stage.
I had forgotten that the last number of CRTs were the phosphor type. My
3BP1 had the standard green medium persistence general purpose phosphor.
Brian
On 16/02/2013 14:48, Bob Landman wrote:
> 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.
>>>
>>>
>>>
>>> __________________________________________________________________________
>>> This email has been scanned by the Symantec Email
>>> Security.cloud service.
>>> For more information please contact helpdesk at x2960 or
>>> [log in to unmask] <mailto:[log in to unmask]>
>>>
>>> ____________________________________________________________________
>>> __
>>> ____
>>>
>>>
>>>
>>> __________________________________________________________________________
>>> This email has been scanned by the Symantec Email
>>> Security.cloud service.
>>> For more information please contact helpdesk at x2960 or
>>> [log in to unmask] <mailto:[log in to unmask]>
>>>
>>> ____________________________________________________________________
>>> __
>>> ____
>>>
>>>
>>> __________________________________________________________________________
>>> This email has been scanned by the Symantec Email Security.cloud
>>> service.
>>> For more information please contact helpdesk at x2960 or
>>> [log in to unmask] <mailto:[log in to unmask]>
>>>
>>> ____________________________________________________________________
>>> __
>>> ____
>>>
>>>
>>> __________________________________________________________________________
>>> This email has been scanned by the Symantec Email Security.cloud
>>> service.
>>> For more information please contact helpdesk at x2960 or
>>> [log in to unmask] <mailto:[log in to unmask]>
>>>
>>> ____________________________________________________________________
>>> __
>>> ____
>>>
>>>
>>
>> _____________________________________________________________________
>> _ This email has been scanned by the Symantec Email Security.cloud
>> service.
>> For more information please contact helpdesk at x2960 or
>> [log in to unmask]
>> _____________________________________________________________________
>> _
>>
>> _____________________________________________________________________
>> _ This email has been scanned by the Symantec Email Security.cloud
>> service.
>> For more information please contact helpdesk at x2960 or
>> [log in to unmask]
>> _____________________________________________________________________
>> _
>>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or
> [log in to unmask]
> ______________________________________________________________________
>
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________
PG&E is committed to protecting our customers' privacy.
To learn more, please visit http://www.pge.com/about/company/privacy/customer/
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
