"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 18/02/14 18:33, Michael Black wrote:
On Tue, 18 Feb 2014, Brian Reay wrote:


The Sinclair was also RPN, as were the early Texas calculators I
think. Sinclair lacked the "Enter" button, using the + key its place.

I don't remember the TI calculators having RPN. I remember them as
being more reasonably priced versions of "electronic slide rules", which
was what they called them originally.

I recall the "electronic slide rule" jargon being used. I could be wrong
about the early TIs. I have an American friend who may know, he was a TI
user as I recall.


It's odd to look back now. I think that HP35 that a fellow ham got in
1972 or maybe 73 (a group buy at his place of employment) was the first
pocket calculator I ever saw close up. So many functions, yet so few
compared to what you can get on a $10 calculator today

I don't know what the first TI scientific calculator cost, but it was
less than the HP by far, and soon you could get one in the $50 range,
and then $30 range, which is when I got my TI-30.

I invested in a TI50 to start my Uni. course, it cost around £50 as I
recall, The next model up, with the card reader, was about double that.

The Japanese were just bringing cheaper calculators into the market at
the time- Commodore in particular. This was 1979/80.

Such a big change, a sudden surge in articles in the ham magazines
showing equations, suddenly you could actually work things out without
needing much math skill.


As a Mathematician, I would argue that calculators enter the game when
it has become arithmetic ;-) (However, as few know the difference I tend
to 'go with the flow' before someone refers to one of my widely
circulated articles.)

I think it was the National scientific calculator that had RPN, coming
later but also being quite cheap.

I don't recall those. The only calculators I recall using RPN are HP,
Sinclair, and (I thought) some early TI ones- although that may be an error.


For the 'everyday' user, RPN was not popular and calculators offering,
almost, algebraic, entry became more popular. I think the first
calculator to offer true algebraic entry (ie following BODMAS/BIDMAS
convention) was Texas. Even today some cheap calculators don't follow
the convention. One of the many things I warn pupils of when I teach
calculator use.

That's interesting. I look at the cheapest of the cheap scientific
calculators, and the functions are at least the same as my TI-30 from
about 1977. I assume the calculators have gotten so cheap because the
work was done long ago, buying old technology to implement cheap today.

It is common to see 'clones' of quite respectable calculators which
function as the originals and only differ in their name and case colour.
Probably common parts.

The ones I was referring tend to be simple 4 function (or perhaps 4
function and a couple of others eg % Mem) which real 'cheapies'.

Perhaps it is just old designs no one has corrected.

--
73
Brian
G8OSN/W8OSN
www.g8osn.net

"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.

In message , Brian Reay writes
On 18/02/14 15:21, Phi wrote:
I paid about £180 for an HP35 in 1973, this calculator used reverse
polish notation (no equals key).
That seems cheap for an HP at the time. As I recall, that was the
launch price of the Sinclair, although it soon dropped.

The Sinclair was also RPN, as were the early Texas calculators I think.
Sinclair lacked the "Enter" button, using the + key its place.

For the 'everyday' user, RPN was not popular and calculators offering,
almost, algebraic, entry became more popular. I think the first
calculator to offer true algebraic entry (ie following BODMAS/BIDMAS
convention) was Texas. Even today some cheap calculators don't follow
the convention. One of the many things I warn pupils of when I teach
calculator use.


I used a National Semiconductor 4640 RPN calculator for about 30 years.
So much so that I can't use a "normal" calculator. I've still got it but
it needs the charger socket and the batteries replaced.

RPN can't be beat for long chain calculations.

My Window desktop calculator is RPN

http://excalibur.en.softonic.com/

Brian
--
Brian Howie

In message , gareth
writes
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

How does the receiver work ?

DIJ
--
Brian Howie

"Brian Howie" wrote in message
...
In message , gareth
writes

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

How does the receiver work ?

My assumption (YMMV) is that the key increases the power
from the oscillator on TX (and thus will cause a tracer on RX
and on QSK operation), the FET being used to switch RIT
in and out.

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 20:21, Brian Howie wrote:
In message , Brian Reay writes

For the 'everyday' user, RPN was not popular and calculators offering,
almost, algebraic, entry became more popular. I think the first
calculator to offer true algebraic entry (ie following BODMAS/BIDMAS
convention) was Texas. Even today some cheap calculators don't follow
the convention. One of the many things I warn pupils of when I teach
calculator use.


I used a National Semiconductor 4640 RPN calculator for about 30 years.
So much so that I can't use a "normal" calculator. I've still got it but
it needs the charger socket and the batteries replaced.

RPN can't be beat for long chain calculations.


True.

Either way, RPN as the user interface has become a 'niche' market. Do HP
still offer RPN?

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.