Discussion:
Tubes vs. Integrated circuits
(too old to reply)
undefined Hancock-4
2021-06-14 19:43:59 UTC
Permalink
In the early 1960s, Electronics Magazine hosted advertisements for both vacuum tubes and the new integrated circuits.

Vacuum tubes were still very much around. Manufacturers invested in improvements in performance, reliability, and cost. New tubes were developed for hi-fi/stereo, UHF and color television, and military needs.

Integrated circuits, the earliest chips, were just being advertised.

Here are examples of ads both tubes and ICs. The tube ads are interesting as they show the various improvements being made to tubes in the early 1960s.

TI solid circuit--I think this is a pioneer integrated circuit from TI, uses the phrase "integrated circuit bars".
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-08-24-OCR-Page-0014.pdf#search=%22solid%20circuit%20semiconductor%22
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-08-24-OCR-Page-0015.pdf#search=%22solid%20circuit%20semiconductor%22

Fairchild --building a microcircuit
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-03-01-OCR-Page-0074.pdf#search=%22custom%20toggle%20circuit%22
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-03-01-OCR-Page-0075.pdf#search=%22custom%20toggle%20circuit%22

Tung Sol Compactron
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-08-24-OCR-Page-0009.pdf#search=%22tung%20sol%20compactron%22

Tung Sol computer tube
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-07-27-OCR-Page-0009.pdf#search=%22tung-sol%20computer%20tube%22

Hitachi tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-09-14-OCR-Page-0081.pdf#search=%22international%20importer%22

RCA Novar hi-fi tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-04-13-OCR-Page-0120.pdf#search=%22rca%20t-12%20novar%22

RCA high sensitivity low cost tube
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-09-07-OCR-Page-0234.pdf#search=%2250eh5%22

RCA bonded cathode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-11-15-OCR-Page-0108.pdf#search=%22rca%20bonded%20cathode%22

RCA dark heater
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/61/Electronics-1961-03-03-OCR-Page-0100.pdf#search=%22rca%20dark%20heater%22
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/61/Electronics-1961-09-01-OCR-Page-0080.pdf#search=%22rca%20dark%20heater%22

Raytheon improved tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-09-14-OCR-Page-0017.pdf#search=%22raytheon%20reliable%20receiving%22

GE five star tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/61/Electronics-1961-07-07-OCR-Page-0067.pdf#search=%22highest%20reliability%22

Sylvania computer tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-12-20-OCR-Page-0017.pdf#search=%22sylvania%20computer%20tube%22

https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/60/Electronics-1960-11-25-OCR-Page-0019.pdf#search=%22sylvania%20tube%20news%20computer%22

Amperex premium
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/60/Electronics-1960-09-23-OCR-Page-0029.pdf#search=%22computer%20pentode%22
Charlie Gibbs
2021-06-14 21:22:37 UTC
Permalink
Post by undefined Hancock-4
In the early 1960s, Electronics Magazine hosted advertisements for
both vacuum tubes and the new integrated circuits.
Vacuum tubes were still very much around. Manufacturers invested
in improvements in performance, reliability, and cost. New tubes
were developed for hi-fi/stereo, UHF and color television, and
military needs.
Integrated circuits, the earliest chips, were just being advertised.
<snip>

I remember that when transistor radios first came out, a big selling
point was that when you turned them on, they started playing instantly;
you didn't have to wait for the tubes to warm up. TVs still needed
some tubes, but developed "instant-on" circuits that kept a low
voltage on the heaters so that they'd come up quickly.

Nowadays, with nary a tube in sight, it takes just as long for
a TV to become ready. I tell people that it's warming up (and
usually get a blank stare in response).
--
/~\ Charlie Gibbs | They don't understand Microsoft
\ / <***@kltpzyxm.invalid> | has stolen their car and parked
X I'm really at ac.dekanfrus | a taxi in their driveway.
/ \ if you read it the right way. | -- Mayayana
Thomas Koenig
2021-06-15 09:53:39 UTC
Permalink
Post by Charlie Gibbs
Post by undefined Hancock-4
In the early 1960s, Electronics Magazine hosted advertisements for
both vacuum tubes and the new integrated circuits.
Vacuum tubes were still very much around. Manufacturers invested
in improvements in performance, reliability, and cost. New tubes
were developed for hi-fi/stereo, UHF and color television, and
military needs.
Integrated circuits, the earliest chips, were just being advertised.
<snip>
I remember that when transistor radios first came out, a big selling
point was that when you turned them on, they started playing instantly;
you didn't have to wait for the tubes to warm up. TVs still needed
some tubes, but developed "instant-on" circuits that kept a low
voltage on the heaters so that they'd come up quickly.
Transistor radios effectively killed of a promising market
for Stirling motors. They could simply run on batteries...
Ahem A Rivet's Shot
2021-06-15 12:11:16 UTC
Permalink
On Tue, 15 Jun 2021 09:53:39 -0000 (UTC)
Post by Thomas Koenig
Transistor radios effectively killed of a promising market
for Stirling motors. They could simply run on batteries...
I recall a battery valve radio, with two batteries a 6V one for the
heaters and a 90V one for the HT - testing the 90V one by tongue was
inadvisable.
--
Steve O'Hara-Smith | Directable Mirror Arrays
C:\>WIN | A better way to focus the sun
The computer obeys and wins. | licences available see
You lose and Bill collects. | http://www.sohara.org/
gareth evans
2021-06-15 14:03:42 UTC
Permalink
Post by Ahem A Rivet's Shot
On Tue, 15 Jun 2021 09:53:39 -0000 (UTC)
Post by Thomas Koenig
Transistor radios effectively killed of a promising market
for Stirling motors. They could simply run on batteries...
I recall a battery valve radio, with two batteries a 6V one for the
heaters and a 90V one for the HT - testing the 90V one by tongue was
inadvisable.
A recent Repair Shop episode had 10-off PP3 batteries wire in series
to create the 90V for an old repair
Douglas Miller
2021-06-15 16:48:39 UTC
Permalink
Post by Ahem A Rivet's Shot
On Tue, 15 Jun 2021 09:53:39 -0000 (UTC)
Post by Thomas Koenig
Transistor radios effectively killed of a promising market
for Stirling motors. They could simply run on batteries...
I recall a battery valve radio, with two batteries a 6V one for the
heaters and a 90V one for the HT - testing the 90V one by tongue was
inadvisable.
...
I acquired a "farm radio" awhile ago, vacuum tubes and batteries (something like 6V and 90V). Even had an odd "cell" that was used to force a voltage drop (replaced by modern "coin cell" battery). They were apparently fairly common in this part of the country, as many farms did not have electricity until the latter half of the 20th century. I'm not sure if transistor radios butted up against that market, but it would have been close.
Scott Lurndal
2021-06-15 17:25:17 UTC
Permalink
On Tue, 15 Jun 2021 09:53:39 -0000 (UTC)=20
=20
Transistor radios effectively killed of a promising market=20
for Stirling motors. They could simply run on batteries...
I recall a battery valve radio, with two batteries a 6V one for the=20
heaters and a 90V one for the HT - testing the 90V one by tongue was=20
inadvisable.
...
I acquired a "farm radio" awhile ago, vacuum tubes and batteries (something=
like 6V and 90V). Even had an odd "cell" that was used to force a voltage =
drop (replaced by modern "coin cell" battery). They were apparently fairly =
common in this part of the country, as many farms did not have electricity =
until the latter half of the 20th century. I'm not sure if transistor radio=
s butted up against that market, but it would have been close.
A Stewart Warner model 303, by any chance?

I've got the one from my Grandparents attic in Wisconsin.

Requires an "A" battery and two "B" (45v) batteries.
undefined Hancock-4
2021-06-15 19:52:21 UTC
Permalink
The 6J6 that I mentioned in previous post was available
by 1945 (may have been available in 1942).
I believe IBM mentioned that particular tube as especially troublesome (write up in bitsavers).
Quadibloc
2021-06-17 06:55:09 UTC
Permalink
Post by undefined Hancock-4
The 6J6 that I mentioned in previous post was available
by 1945 (may have been available in 1942).
I believe IBM mentioned that particular tube as especially troublesome (write up in bitsavers).
I couldn't find anything relevant at Bitsavers, but Ed Thelen's Nike Missile Web Site quotes
the book "IBM's Early Computers" from MIT Press about it:

http://ed-thelen.org/comp-hist/IBM-604.html

John Savard
Robin Vowels
2021-06-17 13:25:46 UTC
Permalink
Post by Quadibloc
Post by undefined Hancock-4
The 6J6 that I mentioned in previous post was available
by 1945 (may have been available in 1942).
I believe IBM mentioned that particular tube as especially troublesome (write up in bitsavers).
I couldn't find anything relevant at Bitsavers, but Ed Thelen's Nike Missile Web Site quotes
http://ed-thelen.org/comp-hist/IBM-604.html
.
Interesting.
The 6J6 was used extensively in the English Electric DEUCE, a very reliable
machine.
undefined Hancock-4
2021-06-26 19:58:07 UTC
Permalink
Post by Quadibloc
Post by undefined Hancock-4
The 6J6 that I mentioned in previous post was available
by 1945 (may have been available in 1942).
I believe IBM mentioned that particular tube as especially troublesome (write up in bitsavers).
I couldn't find anything relevant at Bitsavers, but Ed Thelen's Nike Missile Web Site quotes
http://ed-thelen.org/comp-hist/IBM-604.html
One of the early computer symposiums, listed in the IBM section, talks about machine reliability. All the pioneers had lots of problems. The early circuits were unreliable. Anyway, the IBM rep said the 6J6, used in their 604 calculator, was particularly troublesome.

On a related note, the Williams CRT, used for memory in the earliest IBM computers, was very unreliable. They converted to core as soon as that was perfected (which took some doing as well).

I think the Whirlwind writeups also discussed circuitry issues.

The IBM history discusses this in detail, both the electronic and physical characteristics of audio tubes that needed to be improved for digital service.

In the late 1950s various computer mfrs introduced computer grade tubes, as well as tubes for other tough applications.
Robin Vowels
2021-06-27 00:49:37 UTC
Permalink
Post by Quadibloc
Post by undefined Hancock-4
The 6J6 that I mentioned in previous post was available
by 1945 (may have been available in 1942).
I believe IBM mentioned that particular tube as especially troublesome (write up in bitsavers).
I couldn't find anything relevant at Bitsavers, but Ed Thelen's Nike Missile Web Site quotes
http://ed-thelen.org/comp-hist/IBM-604.html
One of the early computer symposiums, listed in the IBM section, talks about machine reliability. All the pioneers had lots of problems. The early circuits were unreliable. Anyway, the IBM rep said the 6J6, used in their 604 calculator, was particularly troublesome.
On a related note, the Williams CRT, used for memory in the earliest IBM computers, was very unreliable. They converted to core as soon as that was perfected (which took some doing as well).
I think the Whirlwind writeups also discussed circuitry issues.
The IBM history discusses this in detail, both the electronic and physical characteristics of audio tubes that needed to be improved for digital service.
In the late 1950s various computer mfrs introduced computer grade tubes, as well as tubes for other tough applications.
.
Mullard introduced the E90CC in 1955. Good for 10,000 hours.
.
As for the 6J6, it was used in the very reliable DEUCE in large quantities from 1955.
Bob Eager
2021-06-16 06:48:58 UTC
Permalink
Valves operating from batteries featured instant warm-up (the 0.5ma
series such as 1R5, 3V4, 1S4, and so on). These were mainly used in
portable radios.
The first radio I built used valves with a 1.4v filament, quick warm-up,
and 90v anode voltage. They were designed for battery use, of course, but
I used a transformer (lots of exposed main terminals...)

Valves were (British designation) DF96, DAF96, DK96, DL96. B7G base.
--
Using UNIX since v6 (1975)...

Use the BIG mirror service in the UK:
http://www.mirrorservice.org
Robin Vowels
2021-06-17 03:29:54 UTC
Permalink
On Tuesday, June 15, 2021 at 3:25:57 PM UTC+10, Robin Vowels wrote:
.
Valves operating from batteries featured instant warm-up
(the 0.5ma series such as 1R5, 3V4, 1S4, and so on). These
were mainly used in portable radios.
.
Sorry, I made a typo as to filament current. It was 50 ma
for that series.
Ahem A Rivet's Shot
2021-06-14 21:53:48 UTC
Permalink
On Mon, 14 Jun 2021 12:43:59 -0700 (PDT)
Post by undefined Hancock-4
Tung Sol computer tube
Tung Sol valves are still made, there's a matched pair of their
EL34s in my Marshall head.
--
Steve O'Hara-Smith | Directable Mirror Arrays
C:\>WIN | A better way to focus the sun
The computer obeys and wins. | licences available see
You lose and Bill collects. | http://www.sohara.org/
Robin Vowels
2021-06-15 04:12:57 UTC
Permalink
Post by undefined Hancock-4
In the early 1960s, Electronics Magazine hosted advertisements for both vacuum tubes and the new integrated circuits.
Vacuum tubes were still very much around. Manufacturers invested in improvements in performance, reliability, and cost. New tubes were developed for hi-fi/stereo, UHF and color television, and military needs.
Integrated circuits, the earliest chips, were just being advertised.
Here are examples of ads both tubes and ICs. The tube ads are interesting as they show the various improvements being made to tubes in the early 1960s.
TI solid circuit--I think this is a pioneer integrated circuit from TI, uses the phrase "integrated circuit bars".
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-08-24-OCR-Page-0014.pdf#search=%22solid%20circuit%20semiconductor%22
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-08-24-OCR-Page-0015.pdf#search=%22solid%20circuit%20semiconductor%22
Fairchild --building a microcircuit
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-03-01-OCR-Page-0074.pdf#search=%22custom%20toggle%20circuit%22
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-03-01-OCR-Page-0075.pdf#search=%22custom%20toggle%20circuit%22
Tung Sol Compactron
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-08-24-OCR-Page-0009.pdf#search=%22tung%20sol%20compactron%22
Tung Sol computer tube
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-07-27-OCR-Page-0009.pdf#search=%22tung-sol%20computer%20tube%22
Hitachi tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-09-14-OCR-Page-0081.pdf#search=%22international%20importer%22
.
High quality tubes for computer use were developed long before this.
For example, E92CC and E90CC were premium tubes from Mullard, with long life and
slow degradation of performance during their life, compared to the radio tubes ECC92 and ECC90,
respectively. These were in use in computers in the 1950s.
.
Tubes having multiple elements were developed in Germany in the 1920s.
Others were developed in the 1930s, including the 19, or 1J6, the 1D8-GT,
the 3A8-GT, and the 6J6 (already mentioned, possibly developed in the 1940s).
Post by undefined Hancock-4
RCA Novar hi-fi tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-04-13-OCR-Page-0120.pdf#search=%22rca%20t-12%20novar%22
RCA high sensitivity low cost tube
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-09-07-OCR-Page-0234.pdf#search=%2250eh5%22
RCA bonded cathode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-11-15-OCR-Page-0108.pdf#search=%22rca%20bonded%20cathode%22
RCA dark heater
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/61/Electronics-1961-03-03-OCR-Page-0100.pdf#search=%22rca%20dark%20heater%22
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/61/Electronics-1961-09-01-OCR-Page-0080.pdf#search=%22rca%20dark%20heater%22
Raytheon improved tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-09-14-OCR-Page-0017.pdf#search=%22raytheon%20reliable%20receiving%22
GE five star tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/61/Electronics-1961-07-07-OCR-Page-0067.pdf#search=%22highest%20reliability%22
Sylvania computer tubes
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-12-20-OCR-Page-0017.pdf#search=%22sylvania%20computer%20tube%22
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/60/Electronics-1960-11-25-OCR-Page-0019.pdf#search=%22sylvania%20tube%20news%20computer%22
Amperex premium
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/60/Electronics-1960-09-23-OCR-Page-0029.pdf#search=%22computer%20pentode%22
undefined Hancock-4
2021-06-15 19:51:01 UTC
Permalink
Post by Robin Vowels
High quality tubes for computer use were developed long before this.
For example, E92CC and E90CC were premium tubes from Mullard, with long life and
slow degradation of performance during their life, compared to the radio tubes ECC92 and ECC90,
respectively. These were in use in computers in the 1950s.
.
Tubes having multiple elements were developed in Germany in the 1920s.
Others were developed in the 1930s, including the 19, or 1J6, the 1D8-GT,
the 3A8-GT, and the 6J6 (already mentioned, possibly developed in the 1940s).
The point was to show that tube makers were still improving their products even after integrated circuits came out. RCA and others would run ads for tubes for years to come.

In the early 1950s, IBM had trouble getting acceptable tubes for its computers. Apparently so did the rest of the industrial world. In the late 1950s tube makers advertised premium grade tubes.

Some ads for premium tubes;

Tungsol
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/50s/51/Electronics-1951-03-OCR-Page-0029.pdf#search=%22tung%20sol%20electron%20tubes%22
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/50s/51/Electronics-1951-03-OCR-Page-0030.pdf#search=%22tung%20sol%20electron%20tubes%22

Sylvania computer tube 1958
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/50s/57/Electronics-1957-08-OCR-Page-0105.pdf#search=%22computer%20%20tube%22

GE cmputer tube 1957
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/50s/57/Electronics-1957-04-OCR-Page-0053.pdf#search=%22computer%20%20tube%22

RCA preferred
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/50s/58/Electronics-1958-08-15-OCR-Page-0172.pdf#search=%22improved%20cathode%22

Speaking of Mullard, here are some ads from them:
Mullard Tubes

seven tubes for stereo
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/50s/59/Electronics-1959-10-23-OCR-Page-0059.pdf#search=%22type%2045%22

low noise pentode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/60/Electronics-1960-10-21-OCR-Page-0111.pdf#search=%22mullard%22

high gain double triode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/60/Electronics-1960-11-25-OCR-Page-0073.pdf#search=%22mullard%22

high slope pentode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/61/Electronics-1961-09-15-OCR-Page-0073.pdf#search=%22mullard%22

vairable mu pentode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/62/Electronics-1962-01-26-OCR-Page-0020.pdf#search=%22mullard%22

VHF triode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-01-25-OCR-Page-0101.pdf#search=%22mullard%22

high gain i.f. pentode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/60s/63/Electronics-1963-03-22-OCR-Page-0097.pdf#search=%22mullard%22

audio amp
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/50s/56/Electronics-1956-02-OCR-Page-0116.pdf#search=%22mullard%20high%20fidelity%22

hi-fi pentode
https://worldradiohistory.com/hd2/IDX-Site-Technical/Engineering-General/Archive-Electronics-IDX/IDX/50s/59/Electronics-1959-04-10-OCR-Page-0008.pdf#search=%22mullard%20high%20fidelity%22
Dennis Boone
2021-06-15 05:39:21 UTC
Permalink
Post by undefined Hancock-4
Vacuum tubes were still very much around.
Vacuum tubes still _are_ around. In the US, the tv and radio broadcast
transmitters are migrating to solid state (GatesAir has an 80kW UHF
digital television transmitter, for example), but there are still plenty
of systems out there using tubes bigger than your head to generate tens
of thousands of watts.

I think Svetlana is still producing smaller stuff for audio and ham type
applications, too.

De
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