Bob, Thanks for the link, made my first crystal set in '61 I think I remember using a "state of the art germanium" diode as the detector, wound the coil on a toilet paper tube, I think I did a quartz set too. Last year I found the headphones (carbon) in a box at my parent's ranch no radio though. Made my first AM transmitter, 500mW, in '63 from a kit it was "transistorized". Pat Brian, Check out George Ulm's (W9EVT) website he is '88+ and still climbs his towers, I talk with him every morning that I can. Pat NE6PG -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman Sent: Saturday, February 16, 2013 1:07 PM To: [log in to unmask] Subject: Re: [TN] AR/UR Conformal coatings There were quite a few crystal sets in the old days... http://www.radiolaguy.com/Showcase/Crystal/Gallery-Crystal.htm Bob -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord Sent: Saturday, February 16, 2013 2:59 PM To: [log in to unmask] Subject: Re: [TN] AR/UR Conformal coatings Special for our loved laser doctor, Joyce. /Inge On 16 February 2013 16:48, Joyce Koo <[log in to unmask]> wrote: > You are right. It was greyish shiny. Magic. Everything mount on piece > of flat wood. Open face, no box. > -------------------------- > Sent using BlackBerry > > > ----- Original Message ----- > From: Brian Ellis [mailto:[log in to unmask]] > Sent: Saturday, February 16, 2013 08:45 AM > To: Joyce Koo > Cc: [log in to unmask] <[log in to unmask]> > Subject: Re: [TN] AR/UR Conformal coatings > > Sorry, Joyce, not quartz. Usually galena (lead sulphide) with a cat's > whisker! Built one when I was ~10! Not ROHS witha galena crystal!!! :) > > Brian > > On 16/02/2013 14:44, Joyce Koo wrote: > > Brian, remind me my brother built a quartz crystal radio for me > > way,way > back. The type with a needle in the glass tube with pig tail wires > hanging out. He was my hero for few years, especially, he is younger than me! > (Was convinced and still is that God gave him more brain than mine:). > > -------------------------- > > Sent using BlackBerry > > > > > > ----- Original Message ----- > > From: Brian Ellis [mailto:[log in to unmask]] > > Sent: Saturday, February 16, 2013 02:17 AM > > To: [log in to unmask] <[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 transmission (including any attachments) may contain > > confidential > information, privileged material (including material protected by the > solicitor-client or other applicable privileges), or constitute > non-public information. 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