An Ounce of Practice is worth a Ton of Theory .

Its true that most radio amateurs buy their equipment these days, and that a modern transceiver is almost impossible to repair in the home workshop, but relatively simple equipment can still be made, especially receivers, which have a good performance without being too complex, and give good entertainment as well. The point is that CBers don't understand what is going on, and radio amateurs do. A CB radio is a 'black box' whereas a home-built radio is understood on every level from component to aerial and how it is used.

Regards

Geoff

I think it is unwise to separate theory from practice. Looking back over the theory I had to learn in my fitting and machining trade and toolmaking training, the so called theory was practice written down for the benefit of someone else who had to do the same task at some later stage. Theory saves having to learn everything from scratch. Theory is based on what actually works.

Geoff, maybe in the UK, but here I used to dabble in CB 26Mhz in NZ, and there was quirte a bit of actual work done, modifing our sets, I will admit that the equipment has changed some what since the 1970s. Also into SW listening with an Icom R 71E. I'v up graded the filters, and fitted the FM modual to the Icom. My interest in the theory, and practice was/ is with aerials/ antenna. Ian S C

There is still quite a high technical content in the RSGB magazine (Radcom), including in recent years some very interesting work on software radios, albeit not in great mathematical detail.

Software radio is an area where you really need to understand the theory in detail in order to have any hope whatsoever of putting it into practice.

Regards,

Andrew

Thought I'd better add a PS:   RSGB = Radio Society of Great Britain

Edited By Andrew Johnston on 09/02/2013 10:57:12

Edited By Andrew Johnston on 09/02/2013 10:58:34

Theory:I used to ask electronics graduate interviewees how a superhet worked - few even knew let alone had built one. Practice: Few even knew which end of a soldering iron was hot.

My gripe with modern consumer electronics is the impossibility of getting the circuit diagrams for repair and anyway there is normally some custom silicon you can't source anyway.

We currently use 100MHz digitising front ends - not seen an IF transformer for years. Now I can get 1GHz front ends with two dozen digital demodulators, 32 by next year. Who needs that - nobody really but it's just digital processing so 32 is as easy as 2.

I know, I know, that's the end where you go 'ow' and drop it after you've picked it up.

Andrew

PS: But I do know how a superhet works, and I have built one.

I rember reading Neville Duke's autobiography as a boy, I must borrow it off Dad again.

Theroy vs. practice? I think the real meaning isyou can have all the book learning you want, but until you have done it wioth your own hands you can't be an expert.

An obvious example is playing a musical instrument.

From my own background of conservation land management, until you have actually seen what animals, weather and various other unforeseen factors do to your carefully laid plans over a few seasons, all the ecological theory you learnt makes you over-confident of your own abilities.

Neil

I built a software defined radio from a kit, cost me £30. (A Softrock 40) The theory is easy, being only quadrature reception. Download a simple bit of software like Rocky and you are in business. Great fun! Now thinking of a Funcube Dongle Pro +

Good to see other electronics types on here. NB, not all electronics graduates have studied radio frequency engineering.

Regards

Geoff

In my experience most people who say that theory doesn't work don't know the difference between theory and hypothesis.

Russell, who studied electronics and communications in the analogue age.

The Serbs jiggled about with their radio stuff to shoot that F-117A down during the Serbian bombing campaign

**LINK**

They switched from HF to LF or sumfink like that

Anyway, bottom line is a few "amateurs" made a very high tech plane almost obsolete overnight

btw The missile they used was from the 1960s

Edited By Ady1 on 09/02/2013 14:42:57

Some while ago I worked PT for a local firm of agricultural engineers. One of the team was a student from Leeds working towards a degree in engineering. He got his practical experience with our firm since the Health and Safety rules had closed workshops at the college.

Very early on in my time there he asked me to show him how to fit a hacksaw blade, to be more accurate, which way round it was fitted.

I later spent quite a lot of time showing him how to hand sharpen drills; I could understand that since it doesn't come easily, but to be close to qualifying as an engineer without the very first of basic practical understanding and knowledge worries me. He is proably directing jobs on site now.

Brian

Edited By Brian Wood on 09/02/2013 16:33:25

Further back in this thread was mention of Titanic being let down [no pun intended] by inferior rivets, and blaming that on the accountants. That may not actually be true, but this story is.

In the later stages of Rolls Royce's readying of the RB211 big fan jet engine for service [late 1960's] a very expensive cock up was laid directly at the door of the bean counters.

The compressor drum on these engines is made up from many discs in titaniiun alloy,. electron beam welded together at the narrow rim sections a little below the fir tree roots holding the blading. The process is carried out in a vacuum chamber and superb welds are the result. To prevent beam impingement onto the weld on the far side of the drum a sacrificial backing plate catches any 'blow by'

Unknown to the team at RR, after successful trials, plain mild steel backing plates were substituted in an attempt to save money instead of ordering the expensive titanium alloy versions. The result was that production drums were welded up and contaminated on the inside with a brittle eutectic alloy of 40% iron and titanium which was undetectable by both elecrical and magnetic methods.

It was found by chance to rust easily and that was the only way of reliably sorting out the rogues. I believe the entire batch were scrapped since chances could not be taken. The cost ran into millions taking lost lead times into account as well as scrapped materials .

Brian

Brian,

A more prosaic but perhaps equally irritating example is using carbon steel screws in oak site furniture instead of brass or stainless.

Neil

Sorry I didn't explain myself very well; I meant a radio that does the A/D conversion directly from RF, so the whole signal chain is digital, except for a front end broadband amplifer/attenuator.

Regards,

Andrew

I always thought it stood for the Ready, Steady, GO! Brigade

Andy

G1 B**

Dad used to say to me easy to cut off a bit but harder to put back on.
Think before you cut.

Bob

Well put Michael.

Russell

Having done the practice will definiteley affected the way you design things. Back in the 70s I was coming towards the end of long and rough night shift when I was called to fix an ATE (Automatic Test Equipment) that had gone down. I quickly found that a power supply had died, so I whipped out the Power Supply Tray out and fitted in a new one. Unfortuneately tray had two leads with identical connectors and of course I connected them the wrong way round. This caused so much damage that it took us two weeks to repaire the machine. This and other experiences stuck with me and when I designed equipment I would specify different connectors so its not possible to connect things wrongly.

Regards

Luigi

I can think of one example where that old saying is definitely true.

Back in another life I had to use a Swiss jig grinder to shape punches and dies to stamp out among other things, foils caps for yoghurt pots - you know, the sort that have a tab on for fingers to grip and pull of. It was all angles and merging radii and the drawing called for just .0001" (tenth of a thou) clearance between punch and die and poor old Charlie in the drawing office nearly had a nervous breakdown trying to get all the various co-ordinates in their correct positions.

Somehow, he never really got it right. The solution I discovered, was to grind the punch profile first then fit it to the die using my advanced Mk1 lash up which consisted of a torch bulb connected to a PP3 battery. The bulb went underneath the die and the punch was lowered to the surface of the die. Using this method I was able to grind the rest of the die profile to a finish to within aforesaid tolerance. It took me a lot of practice but using this method allowed me to SEE the clearance rather than measure it. I have to admit that the contact earphones supplied with the HAUSER made it possible. It was a great success and 40 years later I like to imagine that some of my tools are still punching out the caps on your yogurt pots.

Theory has its place and so does practice. I think we humans are very good at selecting either/or to get the best end result.

ATB

Stuart

Michael Williams summed it up nicely.

As a former Airframe Fitter/Design Draftsman/Production Engineer I feel that I'm qualified to sit firmly on the fence.

Practitioners are fine within their area of expertise, but ask them to step outside that area and you could be in for big trouble. For instance I used to work with a brilliant machine tooling draftsman. He was asked to design and draw a product (not a piece of tooling) and it was a disaster. I ended up doing it for him. Then I found out that he was receiving 45% more salary than I was, not very pleasing.

The theoreticians shortcomings have been well discussed here!!

In an ideal world the practitioner and the theoretician would march off into the future in lock step.

cheers

Bill

Maybe I'm not actually sitting on the fence!!