---------------------------------------------------------------------- Message-ID: <f6lacg-otk.ln1@coop.radagast.org> Date: 12 Dec 2019 12:40:15 -0800 From: "Dave Platt" <dplatt@coop.radagast.org> Subject: Re: History trans-Atlantic cable In article <766c7bd8-6722-4f0e-ad97-7069757e1b62@googlegroups.com>, HAncock4 <withheld@invalid.telecom-digest.org> wrote: >When computers came along, computer makers found that tubes used in >audio devices were not reliable enough for high speed digital service. >Tiny faults that weren't noticed in audio service would cause computer >bit errors. Computer makers developed premium grade tubes where the >internal materials were of a higher quality and yield better >performance, and also physical placement of the structures were more >precise. Tubes were also made under cleaner conditions. There were some other differences, as I recall. Tubes designed for consumer-electronics purposes are normally operated with the tube conducting current most or all of the time ("Class A" or "Class AB"). When used in digital applications, as binary (on/off) devices, tubes are often "cut off" much of the time (grid driven negative, no anode current). This cut-off mode can lead to an effect known as "cathode poisoning", where a high-resistance layer develops within the cathode. This reduces tube gain and increases noise, thus leading to a short tube lifetime... not a great thing for a digital computer utilizing thousands of tubes. Tube variants for digital service were made with a different cathode structure which resists cathode poisoning. If I recall correctly, some of these tubes were designed with _less_ attention to some concerns such as microphonics and some other forms of noise, since these were of reduced concern in on/off operation. So, although a tube designed for computer use might be electrically and pin-compatible with the popular 12AX7 dual triode, it might not work out well in an audio-amplifier circuit. Other classes of "premium" 12AX7-compatible tube (optimized for low noise, reduced microphonic effects, etc.) would be a better choice in this sort of application. ------------------------------ Message-ID: <20191215201652.009241163B37@ary.qy> Date: 15 Dec 2019 15:16:51 -0500 From: "John Levine" <johnl@iecc.com> Subject: Re: FCC advances plans for 988, a national suicide- prevention hotline In article <8C0C08FF-70A1-4B5C-8AD4-13F3E706B1DD@roscom.com> you write: >FCC advances plans for 988, a national suicide-prevention hotline > >U.S. suicide rates are at their highest levels since World War II. > >The Federal Communications Commission is moving forward with plans to >make 988 the nation's suicide prevention hotline in the face of a >mental health pandemic that claims more than 130 Americans each day. How's that going to work? There's a lot of 988 prefixes in seven-digit dialing areas. ***** Moderator's Note ***** Good question. According to the FCC, the NPRM it just issued would: Propose to require that all telecommunications carriers and interconnected VoIP service providers make, within 18 months, any changes to their networks necessary to ensure that users can dial 988 to reach the National Suicide Prevention Lifeline. https://docs.fcc.gov/public/attachments/DOC-360939A1.pdf ... but the changes could, I suppose, be as simple as resetting the timeout rules for 988-xxxx calls that fail for lack of digits. Bill Horne Moderator ------------------------------ Message-ID: <36B80362-BFA9-4BFD-8B0F-2A9DADEE70FB@roscom.com> Date: Sun, 4 Feb 2018 11:49:46 -0500 From: Monty Solomon <monty@roscom.com> Subject: Apple offers free repairs for iPhone 7 devices with 'No Service' bug >From: Robert Kester <rkester@remove-this.frontiernet.net> Apple offers free repairs for iPhone 7 devices with "No Service" bug Apple has confirmed that a "small percentage" of iPhone 7 devices are affected by a bug that prevents the phone from connecting to a cellular network, instead displaying "No Service" on the status bar. Typically, this occurs after the iPhone switches off Airplane Mode, and is unable to re-connect to service. The company says the problem is due to a failed component on the main logic board, and will offer free repairs to customers experiencing the issue. https://www.theverge.com/2018/2/3/16968092/apple-iphone-7-no-service-bug-free-repair-program ------------------------------ ********************************************* End of telecom Digest Tue, 17 Dec 2019