Is there a good book for learning about valves/tubes?...

<upsidedown@downunder.com> wrote in message
news:3535jf1d6gcioqq6s4ombgffdm8p37prl6@4ax.com...
One thing limiting the speed was the high tube stray capacitances and
high impedance levels. Finding tubes with good cathode emissivity
might help to design logical circuits with low (say 20-30 V) anode
voltages.

Usually the voltages are modest (~100V), so that adequate current can be
drawn. Low voltage, you need too much cathode area and capacitance, and
your figure of merit (Gm/(Cin+Cout), which has units of frequency) stinks.

And obviously, the FoM doesn\'t change with scale (length/area of cathode).
Though other fixed parameters (like wiring strays) do affect the FoM
in-system, so you don\'t want to use too small of a tube.


Ordinary tubes can have reassemble power gain in grounded grid
configuration even at VHF. A grounded grid flip-flop ??

They can, but not baseband to VHF. Only a few late era planar types could
do that. (Which at the time, were more valuable doing the same ~100MHz
bandwidth around a center frequency of some GHz -- pretty good bandwidth
even today, to be fair!)

That\'s the trick. Example:

I happen to have a carton of subminiature (wire lead) 5702s.

These are your basic general purpose / RF, sharp cutoff pentode. 1W max,
5mS at 100V, 10mA.

In an accidentally-grounded-grid arrangement, these like to oscillate around
400MHz; it\'s the interelectrode ESL+Cp resonant mode I think. (This might
happen accidentally, like in a follower type Hartley oscillator, which
places its tuning capacitor between grid and ground.) They\'re perfectly
capable of operating at high frequencies; the transit time is a nanosecond
or two. (This can be measured with a very low plate load and a fast pulse
generator into the grid. The gain in this configuration is pitiful,
obviously, but you can indeed see the current changing in that time!)

The capacitances are about 4pF plate and 5pF grid *WHEN COLD*. However the
grid capacitance increases when hot -- because the electron cloud has mass,
cool huh? -- to more like 9pF. So the total in cascade is 4+9 = 13pF. Plus
circuit strays.

That gives a FoM = 5mS / (2*pi*13pF) = 61MHz, which is the no-frills (no
peaking) ballpark bandwidth, at unity gain (i.e., a 1/5mS = 200ohm plate
load).

In a practical computer, you\'d need 1/2 to 1/3 of this (even for a tiny
fanout of, well, about as much), and even with peaking (to about double it,
give or take how that works in combination with nonlinear loads like diode
gates), you\'re looking at a maximum clock rate for typical gates of maybe
20MHz.

Which, is still pretty promising; that\'s not much slower than 74HC logic,
and faster than CD4000, scarily enough. It does take about a dozen watts to
compute even fairly simple logic operations though... ECL\'s got nothing on
this!


Of course some shift registers, such as mercury delay lines or 64 us
PAL TV delay lines might be used.

Heh, given that those have been obsolete for a while now too -- not hard to
find though.

I wonder how much data those store. Let\'s see, 64us, at a MHz or two
bandwidth -- they had to store chroma, modulated I believe, so that\'s offset
on a center frequency? -- suggests 2Mbit/s * 64us = 128 bits. Although
that\'s not actually bits, but baud, and more bits could be encoded given
some manner of ADC/DAC system, with adequate SNR and ISI (with whatever ISI
compensation can be afforded).

Not bad for, like, a register file, or perhaps more practically, a cache
line..?

And since it\'s modulated, it needs some encoding. PAM perhaps, which would
be an easy enough way to transmit 2 bits/symbol (BPASK I guess you might
call it?). Probably it would be easy enough making a 4x4 square
constellation (4 bits/symbol) too.

Which puts it up around half a kiB, which isn\'t too shabby. And it would
probably match up well enough with a 5702-based (or other tubes of
comparable performance) machine.

Downside, now you have to \"spin the drum\" or whatever; efficient programming
gets a lot harder...

(I wonder if anyone\'s ever written a compiler/optimizer around such a
constraint? Certainly very little reason to do so today, but as an academic
exercise, maybe interesting.)


A Teletype terminal al should do. One Teletype we used had only
semiconductor mains rectifiers and a TO3 power transistor in the 20 mA
constant current generator. The data generation and decoding was all
electromechanical.

Well, I don\'t know about that. They certainly worked..when they did. How
many of them are even around anymore? And of them, how many are basically
in parts, or in need of extreme-teardown levels of maintenance? :^)

Definitely mechanical wonders; I\'ve quite enjoyed CuriousMarc\'s restoration
series:
https://www.youtube.com/watch?v=_NuvwndwYSY

And absolutely, if you have one in working order -- perfectly compatible
with the same old serial frames we\'ve always used, if at rather low baud
rates. Just insert RS-232 (or TTL, or..) to 20mA converter, and don\'t touch
the high voltages. :)

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
 
On Sunday, August 9, 2020 at 2:06:16 PM UTC-7, david eather wrote:
suggestions please
TIA

Radiotron for one.

Go here and poke around:

https://worldradiohistory.com/

for example, try: Technical & Engineering > Technical Books > Rider Book Library

https://worldradiohistory.com/BOOKSHELF-ARH/Bookshelf_RIder.htm
https://worldradiohistory.com/BOOKSHELF-ARH/Rider-Books/Rider-Inside-the-Vacuum-Tube-1945.pdf
 
On 12.08.20 1:50, Simon S Aysdie wrote:
On Sunday, August 9, 2020 at 2:06:16 PM UTC-7, david eather wrote:
suggestions please
TIA

Radiotron for one.

Go here and poke around:

https://worldradiohistory.com/

for example, try: Technical & Engineering > Technical Books > Rider Book Library

https://worldradiohistory.com/BOOKSHELF-ARH/Bookshelf_RIder.htm
https://worldradiohistory.com/BOOKSHELF-ARH/Rider-Books/Rider-Inside-the-Vacuum-Tube-1945.pdf
Hmm... Nice pdf. Thanks.
 
On Tuesday, 11 August 2020 at 12:39:27 UTC+1, Tim Williams wrote:
\"Phil Hobbs\" <pcdhSpamM...@electrooptical.net> wrote in message
news:rgsipb$17mk$1...@gioia.aioe.org...
EMP-proof serial computer, definitely. ;)
Y\'know, I wonder what kind of performance one of those could do, given
modern architectural and electronic knowledge.

A clock frequency somewhat under a MHz seems reasonable, there\'d be some
tradeoff between tube count and computational power, and with say 16 bit
instruction cycles and standard integer ops (logic, arithmetic, and since
it\'s serial, mul and div are pretty cheap) it should be competetive with,
say, the Apollo Guidance Computer (~50kIPS) or some very impoverished MCUs
(maybe not any 8-bit machines, but those 4-bitters that are still around in
some niches).

The memory of course is always going to be the hard part. If you\'re
reluctant to patch in a modern SRAM, you\'re going to have a hard time doing
much of anything else. (Not bad if you find an old core module in working
condition, I guess.)

But then, you still need all the support hardware to make use of it. Even
just a serial terminal, you either need to get lucky with a surviving
vintage one (where \"vintage\" in this scenario includes any current tech
that\'s surviving?), or make one yourself, which means you\'re going to need a
CRT and support components, rasterizer, character generator, video RAM...
All things which existed in various forms back in the day (delay line might
be okay for the RAM; and there were CRT-ROMs for drawing characters!), but
which weren\'t exactly corner-store items even back then.

Probably the more realistic scenario is developing a hack-friendly Android
OS to use on all those phones that are suddenly less useful without active
base stations, and even if a bunch end up dead for various reasons, there\'s
just so many that will survive. Much easier then to keep the battery
charged, which, automotive and mains chargers are at least as likely to
survive and remain as reliable as they were (which is to say, not always
that much heh, but still), and mains inverters and generators, and car
batteries and alternators, aren\'t going away ever so that should be a good
enough stopping point. (Engines in turn can be fed by gassified wood, for
example.)
Tim

Would VFDs be usable for computation? Not just because they\'re low power & long lived, but also they have matrix-like arrangement of grids & anodes.


NT
 
On 8/10/20 11:50 PM, Phil Hobbs wrote:
> Takes too many tubes. See the IBM 650.

So it\'s technically possible. It\'s just not practical.



--
Grant. . . .
unix || die
 
On Tue, 11 Aug 2020 18:11:37 -0500, \"Tim Williams\"
<tiwill@seventransistorlabs.com> wrote:

Of course some shift registers, such as mercury delay lines or 64 us
PAL TV delay lines might be used.

Heh, given that those have been obsolete for a while now too -- not hard to
find though.

I wonder how much data those store. Let\'s see, 64us, at a MHz or two
bandwidth -- they had to store chroma, modulated I believe, so that\'s offset
on a center frequency? -- suggests 2Mbit/s * 64us = 128 bits. Although
that\'s not actually bits, but baud, and more bits could be encoded given
some manner of ADC/DAC system, with adequate SNR and ISI (with whatever ISI
compensation can be afforded).

Not bad for, like, a register file, or perhaps more practically, a cache
line..?

A serial memory (shift register) is ideal for a serial machines. For
addition/subtraction. just use little endian format circulating in two
or more shift registers. First, add the LSB from the registers, store
the sum into the second (or third) shift register LSB. Store the carry
bit into a single (tube) flip-flop.

Shift the registers one bit position. Add the next bits and the carry
from the carry flip-flop. Continue with next bits.

This is how handheld calculators work. Some are pure 1 bit variants or
4 bit (BCD) wide registers are used.

The shift register should be as long as the word length (16 to 40
bits) so that the LSB it is ready for the next instruction cycle. The
problem with the 64 us delay is that it also sets the machine cycle or
just 15625 instructions/second. A 64 to 128 bit capacity is
sufficient, since it allows some dead time for instruction decode
etc. before next arithmetic operation restarts. A shorter delay time
would be desirable (e.g. some mercury delay lines) to allow a shorter
instruction cycle.
 
On 2020-08-12 00:46, Grant Taylor wrote:
On 8/10/20 11:50 PM, Phil Hobbs wrote:
Takes too many tubes. See the IBM 650.

So it\'s technically possible.  It\'s just not practical.

Sure, there\'s nothing about tubes that makes parallel architectures
impossible.

You can do a lot of fun stuff that isn\'t practical. My old colleague
Mark Galt, who helped me with my thesis project long ago, did an
all-mechanical Nixie tube clock that is a thing of great beauty:
<http://markoapparatus.com/portfolio/machine-clock/>

I just ran across it yesterday, in fact. Check out the 45-second video.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Tue, 11 Aug 2020 01:50:21 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-11 00:40, Grant Taylor wrote:
On 8/10/20 4:47 PM, Phil Hobbs wrote:
EMP-proof serial computer, definitely. ;)

Why does it have to be serial?  Why can\'t it be parallel?

Takes too many tubes. See the IBM 650.

Cheers

Phil Hobbs

Some of those tube machines had hardware floating point.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On 2020-08-12 01:16, jlarkin@highlandsniptechnology.com wrote:
On Tue, 11 Aug 2020 01:50:21 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-11 00:40, Grant Taylor wrote:
On 8/10/20 4:47 PM, Phil Hobbs wrote:
EMP-proof serial computer, definitely. ;)

Why does it have to be serial? Why can\'t it be parallel?

Takes too many tubes. See the IBM 650.


Some of those tube machines had hardware floating point.

There were giants in those days, for sure. I got to meet one or two of
them when I was at IBM, and heard stories about many more.

It was much more practical in the old days, when (a) there weren\'t any
good alternatives, and (b) you had your own tube design and
manufacturing facility.

I don\'t think anybody makes 6CW4s anymore.

This from the inimitable Ken Shirriff:
<http://www.righto.com/2018/01/examining-1954-ibm-mainframes-pluggable.html>

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On 12/08/20 05:46, Grant Taylor wrote:
On 8/10/20 11:50 PM, Phil Hobbs wrote:
Takes too many tubes. See the IBM 650.

So it\'s technically possible.  It\'s just not practical.

The oldest working computer in the world uses dekatrons,
valves and relays.
https://en.wikipedia.org/wiki/Harwell_computer

The Elliott 803 is a serial computer using germanium
transistors and magnetic components for the logic.

Decca Navigator made a TTL serial computer for avionics
applications.

They might be a starting point for an architecture.

Or you could be seriously radical and build a computer
using neon bulbs. I doubt the reliability would be good :)
 
On 10/08/2020 5:06 am, david eather wrote:
suggestions please
TIA
So you might have noticed there is a wide opinion on the matter in hand :)
 
On 8/11/2020 10:57 AM, Pimpom wrote:
On 8/11/2020 1:16 AM, gray_wolf wrote:
On 10/08/2020 1:30 pm, Silvar Beitel wrote:
On Sunday, August 9, 2020 at 5:06:16 PM UTC-4, david eather wrote:
suggestions please
TIA

Dunno exactly what you\'re looking for, but the suggestions you\'ve gotten so far are for books about designing *with* valves/tubes. Another dimension is the design *of* valves/tubes. If that\'s what interests you, look up \"1940 RCA Vacuum Tube Design.\" (There are also later editions.) You can find free PDFs on the web. I find the subject fascinating (and who knows, it may be relevant again in a post-apocalyptic world :) )


Good question! I\'m wondering what the OP would do if he knew all about tubes?
Build a HiFi amp? Guitar amp?

Good question, yes. So far the OP hasn\'t made clear what he wants
to do. In the absence of such clarification, I\'d guess that most
people who ask the question want to gain enough knowledge about
tubes to be able to a) design tube circuits OR b) repair a tube
amp OR c) simply understand what the fuss is all about without a
specific goal in mind.
RCA\'s RC-** series of tube data books may also be useful. They
include brief explanations of how tubes are constructed as well
as several examples of practical circuits. One of the mid-1960s
editions was among my first books on electronics.

Search for \"RCA receiving tube manual\"
 
On Wed, 12 Aug 2020 01:42:22 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-12 01:16, jlarkin@highlandsniptechnology.com wrote:
On Tue, 11 Aug 2020 01:50:21 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-11 00:40, Grant Taylor wrote:
On 8/10/20 4:47 PM, Phil Hobbs wrote:
EMP-proof serial computer, definitely. ;)

Why does it have to be serial? Why can\'t it be parallel?

Takes too many tubes. See the IBM 650.


Some of those tube machines had hardware floating point.

There were giants in those days, for sure. I got to meet one or two of
them when I was at IBM, and heard stories about many more.

It was much more practical in the old days, when (a) there weren\'t any
good alternatives, and (b) you had your own tube design and
manufacturing facility.

I don\'t think anybody makes 6CW4s anymore.

This from the inimitable Ken Shirriff:
http://www.righto.com/2018/01/examining-1954-ibm-mainframes-pluggable.html

Cheers

Phil Hobbs

Those things sure were ugly.

HP gear was made that way, lots of phenolic and ratty wires. The Tek
ceramic terminal strip construction was maybe the first beautiful
electronics.

I like to design beautiful electronics. It actually works better too.

https://www.dropbox.com/s/af5eds90ub50rf2/J270_Censored.jpg?raw=1





--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On 2020-08-12 10:47, jlarkin@highlandsniptechnology.com wrote:
On Wed, 12 Aug 2020 01:42:22 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-12 01:16, jlarkin@highlandsniptechnology.com wrote:
On Tue, 11 Aug 2020 01:50:21 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-11 00:40, Grant Taylor wrote:
On 8/10/20 4:47 PM, Phil Hobbs wrote:
EMP-proof serial computer, definitely. ;)

Why does it have to be serial? Why can\'t it be parallel?

Takes too many tubes. See the IBM 650.


Some of those tube machines had hardware floating point.

There were giants in those days, for sure. I got to meet one or
two of them when I was at IBM, and heard stories about many more.

It was much more practical in the old days, when (a) there weren\'t
any good alternatives, and (b) you had your own tube design and
manufacturing facility.

I don\'t think anybody makes 6CW4s anymore.

This from the inimitable Ken Shirriff:
http://www.righto.com/2018/01/examining-1954-ibm-mainframes-pluggable.html



Cheers

Phil Hobbs

Those things sure were ugly.

HP gear was made that way, lots of phenolic and ratty wires.

I used to own a couple of those modules (sans tubes) when I was a kid
(circa 1972). I had no idea what they were, so I stripped the passives
out of them and threw them away. :( Made perfect sense at the time.

The Tek ceramic terminal strip construction was maybe the first
beautiful electronics.

I like to design beautiful electronics. It actually works better
too.

https://www.dropbox.com/s/af5eds90ub50rf2/J270_Censored.jpg?raw=1

I agree in general, but sometimes a man\'s gotta do what a man\'s gotta
do, ya know?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Wed, 12 Aug 2020 11:33:40 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-12 10:47, jlarkin@highlandsniptechnology.com wrote:
On Wed, 12 Aug 2020 01:42:22 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-12 01:16, jlarkin@highlandsniptechnology.com wrote:
On Tue, 11 Aug 2020 01:50:21 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-08-11 00:40, Grant Taylor wrote:
On 8/10/20 4:47 PM, Phil Hobbs wrote:
EMP-proof serial computer, definitely. ;)

Why does it have to be serial? Why can\'t it be parallel?

Takes too many tubes. See the IBM 650.


Some of those tube machines had hardware floating point.

There were giants in those days, for sure. I got to meet one or
two of them when I was at IBM, and heard stories about many more.

It was much more practical in the old days, when (a) there weren\'t
any good alternatives, and (b) you had your own tube design and
manufacturing facility.

I don\'t think anybody makes 6CW4s anymore.

This from the inimitable Ken Shirriff:
http://www.righto.com/2018/01/examining-1954-ibm-mainframes-pluggable.html



Cheers

Phil Hobbs

Those things sure were ugly.

HP gear was made that way, lots of phenolic and ratty wires.

I used to own a couple of those modules (sans tubes) when I was a kid
(circa 1972). I had no idea what they were, so I stripped the passives
out of them and threw them away. :( Made perfect sense at the time.

The Tek ceramic terminal strip construction was maybe the first
beautiful electronics.

I like to design beautiful electronics. It actually works better
too.

https://www.dropbox.com/s/af5eds90ub50rf2/J270_Censored.jpg?raw=1

I agree in general, but sometimes a man\'s gotta do what a man\'s gotta
do, ya know?

Cheers

Phil Hobbs

The thing about PCB (schematic and layout) beauty is that the modest
time spent tweaking cosmetics is actually another opportunity to think
and review, to accidentally correct bugs or discover improvements. The
time spent is usually repaid by getting it right first pass. It\'s like
reading and beautifying your own code before you compile and run.

That board works first pass. So far. It makes adjustable delay and
width and amplitude pulses from 0.5 to 45 volts peak, clean with 1 ns
edges. I did that out of lockdown boredom. It\'s all analog, trimpots,
because I didn\'t want to get involved with uP or FPGA code.

There must be a use for it somewhere.

I discovered these:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=srh05

They make anything up to 75 volts into something usable, 12 in my
case. My box can run from 24 or 48 volt warts.








--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
On 10.8.20 0.06, david eather wrote:
suggestions please
TIA

For transmitting use: The Care and Feeding of Power Grid Tubes,
by Eimac, if you can get hold of one. (I\'ll keep mine).

--

-TV
 
On Wed, 12 Aug 2020 21:15:52 +0300, Tauno Voipio
<tauno.voipio@notused.fi.invalid> wrote:

On 10.8.20 0.06, david eather wrote:
suggestions please
TIA

For transmitting use: The Care and Feeding of Power Grid Tubes,
by Eimac, if you can get hold of one. (I\'ll keep mine).

Has anyone mentioned the RCA receiving and transmitting tube manuals?

They had a good PMT manual too.
 
On Wednesday, August 12, 2020 at 2:15:56 PM UTC-4, Tauno Voipio wrote:
On 10.8.20 0.06, david eather wrote:
suggestions please
TIA

For transmitting use: The Care and Feeding of Power Grid Tubes,
by Eimac, if you can get hold of one. (I\'ll keep mine).

I\'d like to see the datasheets on the EEV Klystrons that were used in a Comark UHF TV transmitter that I maintained. 65KW output, per tube. It\'s bee over 30 years, so I don\'t remember their type number. It was the last Comark built with Klystrons. The next transmitter used Klystrodes, instead. Higher efficiency, less cooling required and lower electric bills.
 
On 11/08/2020 12:27 am, Pimpom wrote:
On 8/11/2020 1:16 AM, gray_wolf wrote:
On 10/08/2020 1:30 pm, Silvar Beitel wrote:
On Sunday, August 9, 2020 at 5:06:16 PM UTC-4, david eather wrote:
suggestions please
TIA

Dunno exactly what you\'re looking for, but the suggestions you\'ve gotten so
far are for books about designing *with* valves/tubes.  Another dimension is
the design *of* valves/tubes.  If that\'s what interests you, look up \"1940
RCA Vacuum Tube Design.\" (There are also later editions.) You can find free
PDFs on the web.  I find the subject fascinating (and who knows, it may be
relevant again in a post-apocalyptic world :) )


Good question! I\'m wondering what the OP would do if he knew all about tubes?
Build a HiFi amp? Guitar amp?

Good question, yes. So far the OP hasn\'t made clear what he wants to do. In the
absence of such clarification, I\'d guess that most people who ask the question
want to gain enough knowledge about tubes to be able to a) design tube circuits
OR b) repair a tube amp OR c) simply understand what the fuss is all about
without a specific goal in mind.

The thought just occurred that to me that perhaps he has no electronic
experience at all
and heard the word vacuum tube some where and wondered what the fuss was about.
Twenty five years ago I had a young guy call me at the shop asking about repairing
a jukebox that had no sound. I asked if it was solid state or vacuum tube and he
had
no idea. Being a ham from 1953 I was shocked at his reply. I thought everybody knew
about tubes.
 
On Wednesday, August 12, 2020 at 10:08:51 PM UTC-4, gray_wolf wrote:
On 11/08/2020 12:27 am, Pimpom wrote:
On 8/11/2020 1:16 AM, gray_wolf wrote:
On 10/08/2020 1:30 pm, Silvar Beitel wrote:
On Sunday, August 9, 2020 at 5:06:16 PM UTC-4, david eather wrote:
suggestions please
TIA

Dunno exactly what you\'re looking for, but the suggestions you\'ve gotten so
far are for books about designing *with* valves/tubes.  Another dimension is
the design *of* valves/tubes.  If that\'s what interests you, look up \"1940
RCA Vacuum Tube Design.\" (There are also later editions.) You can find free
PDFs on the web.  I find the subject fascinating (and who knows, it may be
relevant again in a post-apocalyptic world :) )


Good question! I\'m wondering what the OP would do if he knew all about tubes?
Build a HiFi amp? Guitar amp?

Good question, yes. So far the OP hasn\'t made clear what he wants to do.. In the
absence of such clarification, I\'d guess that most people who ask the question
want to gain enough knowledge about tubes to be able to a) design tube circuits
OR b) repair a tube amp OR c) simply understand what the fuss is all about
without a specific goal in mind.

The thought just occurred that to me that perhaps he has no electronic
experience at all
and heard the word vacuum tube some where and wondered what the fuss was about.
Twenty five years ago I had a young guy call me at the shop asking about repairing
a jukebox that had no sound. I asked if it was solid state or vacuum tube and he
had
no idea. Being a ham from 1953 I was shocked at his reply. I thought everybody knew
about tubes.

Back in the \'60s and early \'70s, we had customers who didn\'t know whad brand of TV they owned, even though they stared at their TV for hours every day.. Others asked, \'Aren\'t all TVs RCA?\'. Each service truck\'s inventory of spare parts was tailored to a couple brands. If the wrong brand was given, the tech had to haul their set to the shop, rather than make extra trips. It was amazing the high percentage of people who were too lazy to walk over to their TV to get at least a brand, if not the model number so the tech could take the service data with them. That was a big reason that I left consumer electronics.
 

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