In article ,
Jerry Stuckle wrote:

On 2/18/2014 5:58 AM, gareth wrote:
There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost nearly
a week's wages for the average working man, and so it was good economical
sense to try and use it as many ways as possible simultaneously.

Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of switching
(manual, relays) which would be the major outlay?

Not carping, just curious.

-----ooooo-----

BUT BUT BUT, this one has no switching, apart from the Morse Key! ...


http://www.vk2zay.net/article/file/1138



I'm not familiar with this particular challenge - but similar ones I've
seen are more about the design than the cost.

Jerry, AI0K

True, but it is still a ridiculous constraint. It is about as sensible
as designing something where the first digit of every component value
had to be '4'.

--

Percy Picacity

On 2/18/2014 9:05 AM, Percy Picacity wrote:
In article ,
Jerry Stuckle wrote:

On 2/18/2014 5:58 AM, gareth wrote:
There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost nearly
a week's wages for the average working man, and so it was good economical
sense to try and use it as many ways as possible simultaneously.

Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of switching
(manual, relays) which would be the major outlay?

Not carping, just curious.

-----ooooo-----

BUT BUT BUT, this one has no switching, apart from the Morse Key! ...


http://www.vk2zay.net/article/file/1138



I'm not familiar with this particular challenge - but similar ones I've
seen are more about the design than the cost.

Jerry, AI0K

True, but it is still a ridiculous constraint. It is about as sensible
as designing something where the first digit of every component value
had to be '4'.


Not necessarily. It takes skill to minimize components in a design
without degrading performance. Anyone with a modicum of RF design
experience can design a 5 or 10 transistor transmitter which has
reasonable output and no chirp. To do so with 2 transistors is much
more difficult.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

Jerry Stuckle wrote:
On 2/18/2014 9:05 AM, Percy Picacity wrote:
In article ,
Jerry Stuckle wrote:

On 2/18/2014 5:58 AM, gareth wrote:
There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost nearly
a week's wages for the average working man, and so it was good economical
sense to try and use it as many ways as possible simultaneously.

Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of switching
(manual, relays) which would be the major outlay?

Not carping, just curious.

-----ooooo-----

BUT BUT BUT, this one has no switching, apart from the Morse Key! ...


http://www.vk2zay.net/article/file/1138



I'm not familiar with this particular challenge - but similar ones I've
seen are more about the design than the cost.

Jerry, AI0K

True, but it is still a ridiculous constraint. It is about as sensible
as designing something where the first digit of every component value
had to be '4'.


Not necessarily. It takes skill to minimize components in a design
without degrading performance. Anyone with a modicum of RF design
experience can design a 5 or 10 transistor transmitter which has
reasonable output and no chirp. To do so with 2 transistors is much more difficult.

Indeed. This reminds me of the classic story about pre-Apple Woz
redesigning an Atari game's circuit design and taking the IC count down by
two-thirds or so, earning a fee for each one he pulled out of the design.
Steve Jobs then stole most of the total fee by telling Woz that the
commission was worth about a tenth of what it was in reality, but that's
another tale for another day!

--
Stephen Thomas Cole // Sent from my iPhone

On Tue, 18 Feb 2014, Percy Picacity wrote:

In article ,
Jerry Stuckle wrote:

On 2/18/2014 5:58 AM, gareth wrote:
There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost nearly
a week's wages for the average working man, and so it was good economical
sense to try and use it as many ways as possible simultaneously.

Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of switching
(manual, relays) which would be the major outlay?

Not carping, just curious.

-----ooooo-----

BUT BUT BUT, this one has no switching, apart from the Morse Key! ...


http://www.vk2zay.net/article/file/1138



I'm not familiar with this particular challenge - but similar ones I've
seen are more about the design than the cost.

Jerry, AI0K

True, but it is still a ridiculous constraint. It is about as sensible
as designing something where the first digit of every component value
had to be '4'.

But the constraint causes some to think.

An analogy is the superregenerative receiver. Forty years ago it as still
used in some places, but the various handbooks would give a very brief
description and basically treat it like a black box. It was like broken
telephone, the basics lost to history, "everyone" knowing the basics but
not really.

I remember later seeing a schematic where the quenching was done with a
separate device. The descriptions I'd previously seen had been mostly
about how the same device does the quenching, as if that was important to
understand why there was quenching. Seeing a separate oscillator made me
realize that the quenching oscillator was in effect modulating the
regenerative receiver. No wonder those things were wideband, put a square
wave on any oscillator and and you'd get multiple sidebands.

If you have a separate quenching oscillator, you can better control the
waveform and the "modulation level".

I didn't pursue it, but I realized that if you fiddle with such things,
you might end up with a narrower bandwidth superregen receiver.

And that's what Charles Kitchin did. He had an article in COmmunications
Quarterly where he went back to the early days of the receiver, understood
what was going on back then, and then tried to update it, with solid state
devices, but also by trying to control the quenching. And he claims he
has narrower superregen receivers.

I never saw the article, I did see some standalone superregen receivers he
talked about. But, the original article got flack "why dredge up the
superregen when nobody uses it and it's obsolete?". Precisely because in
going back to the beginning, he regenerates those beginnnings, so the
knowledge of the early days is out in present view for anyone interested
to pursue further.

He did the same with a similar article later in Communications QUarterly
about the regnerative receiver.

Knowledge gets lost. An idea becomes commonplace so the details are
boiled down, leaving so much that was discovered in the early days, or at
least discussed in the early days, missing from current books and
magazines. Only when you look at something as originally portrayed can
you give it a boost in current technology and maybe leap ahead.

Ladder filters were around for a long time before they made it big.

People spent endless time trying to improve direct conversion receivers
without really looking in the right direction. Yet, I can point to a 1974
article about proper termination of a mixer in a VHF converter that is
exactly what was done a decade or so later to direct conversion receiver
mixers that really seemed to fix some of the problems.

Or, that mid-1980s direct conversion receiver caused a resurgence in
interest in the phasing method, nothing really new initially but times had
changed, some of the problems lessened by newer technology, and then later
suddenly a realization that one could intersect this with digital signal
processing.

But if you don't fully understand the basics (in part because those basics
are assumed rather than stated), you can't make a leap forward, moving
something from the past into the future by applying the new to the old.

These two transistor challenges are like that, cause people to think and
maybe learn something or create something new.

Michael

"Michael Black" wrote in message
news:alpine.LNX.2.02.1402181412260.14557@darkstar. example.org...
But the constraint causes some to think.

An analogy is the superregenerative receiver. Forty years ago it as still
used in some places, but the various handbooks would give a very brief
description and basically treat it like a black box. It was like broken
telephone, the basics lost to history, "everyone" knowing the basics but
not really.

Both regenerative ans superregenerative RXs are featuring in the approach
known as a "supergainer", as, indeed, are direct conversion RXs, in all
cases, repalcing the IF and product detector stages following the Xtal
filter.


I didn't pursue it, but I realized that if you fiddle with such things,
you might end up with a narrower bandwidth superregen receiver.

If as above, then the governing BW is determined by the Xtal filter


Knowledge gets lost

An outstanding example of that is over here with the floods on the
Somerset levels, where dredging and pumping knowledge going
back to the 1700s (including involvement by, "The Dutchman")
has been lost in 80 years of changes and mergings in the various
drainage and water catchment authorities and we are now left
with the Environment Agency run by dogooders who though it
to be more appropriate to blow up the pumping stations, omit
the dredging, and devote the money and effort into making
nature reserves!

. An idea becomes commonplace so the details are boiled down, leaving so
much that was discovered in the early days, or at least discussed in the
early days, missing from current books and magazines.

I found this out over 10 years ago, when I wanted to find out how
a railway steam locomotive REALLY worked,
and had to go back
to books from the 1920s and 1930s when it was THE technology of the
day, and every boys' book described it in some detail.

On Tue, 18 Feb 2014, gareth wrote:

There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost nearly
a week's wages for the average working man, and so it was good economical
sense to try and use it as many ways as possible simultaneously.

Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of switching
(manual, relays) which would be the major outlay?

Not carping, just curious.

There have always been "contests" like that, though sometimes they were
about "build a whole receiver using the same transistor type", or "build a
receiver without any ICs" after ICs had come around.

SOme of the time it's not about design, but the building, so one can just
copy what existed.

In some cases, this is just about getting people to build something, so a
two transistor whatever is simple and might attract more people.

But in suggesting a problem, people may come up with interesting
solutions. I remember a bit years ago where a bipolar transistor was used
to generate two different crystal controlled frequencies, the frequency
chosen by how polarity was applied. I forget the details, but it relied
ont he transistor having some amplification in an unexpected area.

If people don't have to be frugal, then such things never get found.

Or think about in the thirties. People had little money, so yes, a simple
transceiver would be a great thing. Someone decided to build that, in
effect a tube that was a superrenerative receiver and on transmit a
modulated oscillator. It helped get people on 10metres (I think) and
56MHz, and 112MHz and so on. It would generate activity on an otherwise
unused band because it was cheap and simple, so people built them. The
cost of the switch was less than the cost of the tubes. And every so
often, such a thing would be banned, as rules for more stability came into
effect, and usually by then that band was populated. So the concept moved
to a higher frequency, until it was deemed to unstable for there too, and
up to the next band. They even existed in the 420MHz band, and while
generally nobody built them, at 1296MHz people often got a start with
APX/6 surplus that amounted to simple equipment. 20 to 30 years ago,
23,000MHz got a boost with surplus door openers. SImple equipment gets
more people onto a band than complicated equipment, and some will move on
to fancier equipment.

That same sort of thing, an active element switched between a superregen
receiver and a modulated oscillator still existed till at least 30 years
ago, in license free walkie talkies, first in the 27MHz range and then in
the 49MHz range. Even then the cost of the switch was seen as simpler than
more transistors.

It can also teach something. You can reuse the transistor for two
functions, by switching the three leads of the transistor, which means
much more complication. But if people see that, they may learn that
design can become simpler by more complication. More transistors seem to
complicate things, but if it does away with switching, it may simplify the
design overall.

Michael

"Michael Black" wrote in message
news:alpine.LNX.2.02.1402181359580.14557@darkstar. example.org...
On Tue, 18 Feb 2014, gareth wrote:
There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost nearly
a week's wages for the average working man, and so it was good economical
sense to try and use it as many ways as possible simultaneously.
Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of switching
(manual, relays) which would be the major outlay?
Not carping, just curious.

There have always been "contests" like that, though sometimes they were
about "build a whole receiver using the same transistor type", or "build a
receiver without any ICs" after ICs had come around.

What I find intriguing is the realisation that valves ("tubes" to you?) can
be operated with only 12V on the anode.

On 2/18/2014 3:00 PM, gareth wrote:
"Michael Black" wrote in message
news:alpine.LNX.2.02.1402181359580.14557@darkstar. example.org...
On Tue, 18 Feb 2014, gareth wrote:
There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost nearly
a week's wages for the average working man, and so it was good economical
sense to try and use it as many ways as possible simultaneously.
Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of switching
(manual, relays) which would be the major outlay?
Not carping, just curious.

There have always been "contests" like that, though sometimes they were
about "build a whole receiver using the same transistor type", or "build a
receiver without any ICs" after ICs had come around.

What I find intriguing is the realisation that valves ("tubes" to you?) can
be operated with only 12V on the anode.



I remember back in the 70's we had radar sets with ZERO volts on the
magnetron's anode (DC ground). Of course, there was -3KV or so on the
cathode

I haven't done anything with radar in well over 30 years, so I don't
know if they still do it or not. But I wouldn't be surprised. At first
glance it sounds crazy - but it made for a very simple and efficient way
to couple the output of the magnetron to the waveguide.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

"Jerry Stuckle" wrote in message
...

I remember back in the 70's we had radar sets with ZERO volts on the
magnetron's anode (DC ground). Of course, there was -3KV or so on the
cathode


As in, "Flying by aeroplanes is perfectly safe, it's only when you crash
that it becomes dangerous"? :-)

On 18/02/14 20:31, Jerry Stuckle wrote:

There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost
nearly
a week's wages for the average working man, and so it was good
economical
sense to try and use it as many ways as possible simultaneously.
Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of
switching
(manual, relays) which would be the major outlay?
Not carping, just curious.

There have always been "contests" like that, though sometimes they were
about "build a whole receiver using the same transistor type", or
"build a
receiver without any ICs" after ICs had come around.

What I find intriguing is the realisation that valves ("tubes" to
you?) can
be operated with only 12V on the anode.

No unusual at all.

Not only were a number of valves for the car radio (and possibly other)
markets available, I recall designs which use 'ordinary' valves with
6.3V AC heaters and a voltage doubler and rectifier to provide the "HT".
I recall a one valve design in Radio Constructor, which I build. It was
the 'cover article'. The design called for an Eddystone Box, far too
expensive, so I used a tin box from some short bread.


I remember back in the 70's we had radar sets with ZERO volts on the
magnetron's anode (DC ground). Of course, there was -3KV or so on the
cathode

I haven't done anything with radar in well over 30 years, so I don't
know if they still do it or not. But I wouldn't be surprised. At first
glance it sounds crazy - but it made for a very simple and efficient way
to couple the output of the magnetron to the waveguide.


No reason why it shouldn't be done. I can imagine some of the more
"technically challenged" struggling with it but there are always those
who insist that all who have been designing kit for years have got it
wrong.