How much should one invest in tools to get in the hobby/occasional business?

[peter_scott]

If I could only buy one single piece of equipment it would be a 'scope.

Peter

[G0HZU_JMR]

In my student days I started out with a low cost multimeter and I made an RF detector probe and a crude signal injector.

The RF probe was the classic diode detector type that converted RF to a DC voltage that could be measured with the multimeter. It is possible to faultfind and repair radios quite successfully with just these low cost items. However, it wasn't long before I bought a scope, an RF sig gen and a frequency counter.
In those days there was huge demand for CB/amateur radio servicing so I was repairing quite a few radios a week using this equipment. Those days are long gone for me now, I think I stopped doing that stuff about 30 years ago.

I'd also include a capacitor tester if you want to work on vintage gear and also some form of ESR meter. You could probably buy all of the above today for a few hundred pounds if you buy older test gear although I would recommend to try and experiment with modern technology as this is going to be more reliable and much more versatile.

[TonyDuell]

Originally Posted by Station X

I think you need to look again.

The manufacturer's sheet for the Bush DAC90A shows the voltages in a table on page 5.

The manufacturer's sheet for the Philips 209U shows the voltages in figures 7 and 8.

You are of course correct.

However my main point still stands. The DAC90 sheet states that they were taken with an AVO 7. The latter sheet doesn't appear to say, but they are the same voltage readings as in the Trader sheet so I think it's safe to assume an AVO 8 or similar.

Unless you are planning on owning every type of meter ever made, you have to either learn how to estimate the effects of your meter (I've certainly seen service manuals that state that the readings are the theoretical ones, no allowance being made for the meter loading) or connect a suitable load resistor to a DMM

[Cruisin Marine]

If I could go back in time, and if I then had the money, I would have bought the best I could all down the line.
Tools last on the premise "You get what you pay for" Buy rubbish you keep replacing it. I avoid all Chinese stuff, it is generally a waste of time and money, pay cheap buy thrice or more.
I look out for old British tools or quality from USA and Europe.
For example: One pair of Lindstrom cutters will outlast the lifespan of a busy workshop if looked after. I know this first hand.

As for starters test eqpt, An avo 8 is nice of course, but a small DVM will get you going cheaply, variable power supplies, a 20 MHz plus scope, a signal injector, a simple diode probe, a decent soldering iron is a must, a logic probe if that is what you are working on, a solder sucker will suffice for most jobs. Later you can specialise.

I must warn you, it is never ending, and I mean NEVER- you will always need some gear you haven't yet got. Good luck.

[Sideband]

Originally Posted by ottavio

Assuming one has the technical knowledge and the space (I have neither yet),

All good advice so far but one thing I would like to add is to have a go at building something yourself. There is nothing more rewarding than getting something working that has essentially been built from a 'pile of bits'! Obviously start with something simple. It could be a signal tracer (which is nothing more than a high-gain amplifier) or perhaps you might want to have a go at building a simple radio. There are lots of circuits available on the web but it might be advisable to ask here as well as we all know from experience that some of the web based circuits are somewhat 'enthusiastic' and not always as good as they claim.

When I first got interested in all things radio related, I built crystal sets, and simple transistor sets, some more successful than others and gradually worked up to full superhet valve sets since my main passion then was shortwaves. It is true that there were a lot of magazines around then with circuits for all sorts of things but basically it was all learn by doing and I really believe that you learn most when building things yourself. I also went to evening classes and attained full C & G qualifications but I had a good start with all the experience gained from the above.

Just my thoughts and what worked for me.

[greenstar]

I am very much a learner myself. Each item used needs checking out. Test gear is either new and expensive or vintage and probably more appropriate but of unknown reliability and accuracy. Every used item need checking out. New things cannot always be relied upon (eg, cheapish meters).
I would buy a new decent multimeter firstly. Avos are wonderful, but I think can wander off calibration, and need to be checked (others may correct me here, but it is a nightmare when every meter you have gives a different reading, which will of course be affected by their internal resistance). Then you do need an Avo or similar for the reasons given above, and it's ranges need to be checked.
Lamp limiter, electrolytic reformer, yes.
Component analyser from ebay, chinese wonder, to give accurate resistance/capacitor/inductance readings, although will not be of use in checking leakage. They also test transistors. Good especially for checking resistors and unmarked components.
A multivibrator signal injector is i believe good to have as it produces lots of rf and af noise that doesn't need tuning and can be used to work through the stages. Easy to make. A crude but useful tool.
BVWS auctions, radio rallies etc when you can, lots of amazing test gear at bargain prices. I have a shed full, but the issue is more knowing how to use them, and they are mostly just nice things to play with.
It is easy to be seduced and lost in all the fabulous old test kit to be found when learning to use a meter and understand what it tells you is a fundamental first step.

[Welsh Anorak]

Multimeters are a matter of taste. Many regard AVOs as invaluable. Personally I've never liked them and found them too big, clunky and difficult to use. I have a fairly cheap analogue meter on the shelf but I rarely use it, much preferring my digital meters. The main problem with a 'scope is having somewhere to put it, assuming it's a CRT type. If it's by your side then you'll use it all the time. For that reason a well-designed bench and equipment rack is as important as the equipment you're wanting to use.
However that's just my take on things - others will definitely disagree!

[Sinewave]

I guess how much you want to spend depends on how much you do and enjoy doing, quite like any hobby. Take amateur radio for example, many people drop thousands into a radio, if not hundreds, then the same for antennas.

It's one of those hobbies, you can spend as little or as much as you want.

[paulsherwin]

Another vote for the Chinese component analyser, ten quid very well spent. It may not be a professional lab instrument but will give all sorts of info that would otherwise involve test gear costing hundreds or even thousands.

A two transistor multivibrator signal injector makes an excellent first construction project, simple and cheap. You can build it using scavenged components and birdsnest everything together, or build it on a bit of stripboard. Just google for circuits.

[Keith956]

If I was starting out today the first thing I'd want (apart from a collection of basic tools and soldering iron) would be a cheap digital multimeter. In my portable toolbox I still use a WhiteGold DVM that came from Maplin. With the ability to measure V/I/R/L/C it's handy not just for checking voltage and continuity but checking basic components including diodes and transistors.

After that a digital scope - potentially a big investment although a decent one will last many years and the chinese ones like Siglent and Rigol are very good. I would never get rid of my old Tek 465B that I've had for about 30 years now but a digital scope can do so much more these days.

Agree about building stuff - a simple AF/RF probe for signal tracing / injection is invaluable for fault finding any radio/hifi.

After that you can look out for good old test equipment on ebay etc. If you are prepared to watch and wait you can get some great bargains; they often need a bit of repair but old HP/Tek stuff can be very repairable. For example I picked up a HP34401A 6.5 digit DVM advertised as 'for parts only' for next to nothing and after a lot of head scratching, a 50p IC was all that was needed to get it fully working again.

[Radio Wrangler]

Originally Posted by Keith956

but old HP/Tek stuff can be very repairable.

Their newer stuff is a lot less repairable. Circuit diagrams and service information is now seen as secret. Field repair got changed to just board swapping. Fine if you can afford it and for as long as boards are available, otherwise you're on your own to try to reverse engineer the things. Current Chinese brands are similar.

David

Originally Posted by mhennessy

5. Self study

Where do I start? I did study for the Advanced Licence but not much has stuck to my knowledge. I find it difficult to go past diodes and transistors. Somebody suggested me that I should learn valve tube circuits because they are simpler.

[Peter.N.]

I was in the trade for 50 years and had little more than a multimeter, soldering iron, cutters and screwdrivers. When I started doing colour TVs I did invest in a pattern generator and a scope. If you are going to do a proper refurb on radios you will need a signal generator.

I had no qualifications at all when I started in the '50s, but there was such a shortage of engineers that if you could repair TVs you could get a job, I could and I did, although most of my life I was self employed. I was mad keen on electronics as a kid and could already do repairs before I left school, but that was with analogue and valves the only things I understand really. I wouldn't stand a chance now. The only qualification I have had in my life was the RAE.

Peter

[Station X]

Originally Posted by ottavio

Where do I start?

Here is as good a place as any:-

https://www.vintage-radio.com/repair...ion/index.html

[dave walsh]

This all sounds a bit behind the curve ottavia. You've obviously got a fair amount of knowledge already [apart from valves] and the Forum does contain some very experienced people who do professional repairs for a living. Overall though, it's a hobbyist space. There are some new enthusiasts [post You Tube] who seem to want to repair "by imitation" but you are clearly keen on learning more theory which was previously the only route really. Whatever has drawn us all into this activity, I doubt that anyone had given thought to equipping a whole lab in advance. There is a reason why TV and Radio Repair shops are extremely rare these days. Put that together with "Retro" repair attracting greater interest than ever before [instead of disdain] the difficulty in doing anything with some modern equipment and it looks like a long road that already occupied by others. Although you've had the usual great response with invaluable advice and comment, I doubt that you're primary question can really be covered satisfactorily by any of us. It's a case of "experimenting" to find out!

On the question of space to work, or maybe just accumulate too much "stuff" ["I'm guilty as charged you Honour"] it was common in the sixties and seventies to see articles in the mags about working in a confined space. Some very ingenious designs appeared ranging from using a very small area eg the "coal hole" or a mobile table top about a metre square which could fold back into a "plug in" wooden case complete with power sockets, soldering gear, basic tools, parts etc obviating the need to set everything out each time! [It reminds me, in a way, of the roll top sheets that enable the quick and easy transporting of Jig Saw puzzles these days]. The radio repair ideas may not suit your long term ambition but it might help with deciding what to do for the best in the meantime. Best Wishes.

Dave W

[mhennessy]

Originally Posted by ottavio

Where do I start? I did study for the Advanced Licence but not much has stuck to my knowledge. I find it difficult to go past diodes and transistors. Somebody suggested me that I should learn valve tube circuits because they are simpler.

There are many great textbooks, and everyone will have their favourites. There are also many that aren't so great. Again, personal preference will be a factor there. There are many adult learning styles, so what works for one person might not work so well for another.

Generally, for semiconductors, I'd avoid the "vintage" text books. I have many here, but while lovely to own, I don't think they are good to learn from. There's too much emphasis on the inner semiconductor theory, and not enough about how to use them in practice. They also tend to be mathematics-heavy - not great for a beginner, in my humble - but somewhat informed, given my day job - opinion.

Try the opening chapters of "The Art of Electronics" by Horowitz and Hill. The book is huge, but don't let that put you off - as I say, the opening chapters. For now, at least . There are 3 editions today, but any of them will do, and earlier editions should be easy to find online. Their style is one that works for me and many others, and it makes a refreshing difference to the vast majority of text books I've seen. Maths is kept to the minimum. I still remember discovering it in the university bookshop back in 1991, and I've seen copies on benches (not on shelves gathering dust) at every electronics workplace I've seen since.

Another author I really rate is Douglas Self. He specialises in audio, and doesn't aim to write for absolute beginners, but once you have the basics under your belt, you should find that his explanations are really very good. Again, the maths is kept in check, just as it should be. You might not be interested in audio specifically, but the basics apply to most aspects of analogue electronics.

Of course, the internet is full of resources, but vary enormously in quality. If you're stuck with understanding something specific and want to ask for help, be sure to cite the websites that your are using - that could save a lot of time! Youtube can be excellent, but the same cautions apply. Again, there are lots of different styles out there. For example, some people hate Dave Jones on EEVBlog, but he really knows his stuff, and his tutorial videos can be excellent - he strikes a good balance between practice and theory. His style won't work with everyone, but those who choose to criticise his voice or his enthusiasm are missing the point at best. Another well-known person is Big Clive - his videos are always entertaining, and he's good at getting theory across in an accessible way. I've been meaning to check out the latest videos from Tim Hunkin but haven't had a chance yet. I'm sure many of us fondly remember the "Secret Life" TV programmes (there was a thread here about it recently).

Personally, I don't find valves easier than transistors. Others will disagree and that's fine. Part of the reason for that is my age. I just didn't encounter valves all that often when I was a kid learning about electronics - and although I knew almost nothing about them, I knew enough to be afraid of the high voltages and hot components. One could perhaps argue that the internal workings of the valve are easier to understand than semiconductors, but I'm not all that bothered about that - it's how you use them in circuits that counts, especially at the beginning (by all means come back to the inner theory later if you like).

Some people argue that valves are more rugged than transistors - electrically, at least - and there's some truth there, of course, but this means that some are nervous around transistors. This comes from the era when transistors were new and very, very expensive, and some people were less careful than they should have been. A careless slip with a massive AVO probe in a valve radio was rarely a problem, but do the same with a transistor circuit and it might be disastrous. Of course, the fact that transistor assemblies are usually much smaller doesn't help. One thing that helps here is the use of current-limited power supplies, as I mentioned earlier. It won't save your skin every time, but it will definitely reduce the risk.

[DMcMahon]

Originally Posted by ex seismic

If you are wanting to repair vintage valve radios be aware that the voltages on service sheets were measured with by modern standards a low ohms per volt meter, i.e. an Avo 7. Measuring them with a modern DMM will give erroneous readings which might lead you astray until you have the experience to allow for what will be too high readings. Therefore on my list for you is an Avo 7. This topic has been discussed before on here.

Yes important to be aware of this, but I would not get too hung up about it. In my experience the majority of voltage readings will be very similar between a high impedance digital volt meter/multimeter and an analogue meter. Of course there will always be exceptions, such as a valve circuit with high impedance where the original voltage measurement (as shown on schematic) was done using a low Ohm/V analogue meter.

I view the voltage readings shown on schematics/service sheets as typical ball park readings, i.e. not absolute values that need to be obtained/matched, usually several/many volts either way is nothing to worry about (unless the stated voltage in question is a low value, like some cathode voltages). Most schematics will not show a tolerance for the listed voltages.

Of course always good to have more than one meter for comparison measurement purposes and hard to beat a good Avometer.

For me personally the most importance pieces of test gear is a multimeter and a scope.

David

[Bazz4CQJ]

Originally Posted by cruisinradio

I avoid all Chinese stuff, it is generally a waste of time and money. I look out for old British tools or quality from USA and Europe.

I fully agree that "classic" British and US tools are very desirable bits of kit. I don't agree with "avoid all Chinese stuff", for while some of it is really awful, some of it is quite good. I've just bought some 12" pipe pliers off eBay, which I assume are Chinese, and I'm very happy with them. There's a skill, or an art, to looking at budget-priced stuff from the far east and sensing whether it is outright junk or worth a punt - and probably some luck comes into it. More often than not, I've been satisfied to quite happy with much of my Chinese buys. Definition of Quality; "adequacy for purpose".

B

[G6Tanuki]

It's worth remembering that you already have a rather good audio-frequency signal-generator and storage-scope both with frequency-capabilities extending well beyond the range of human hearing.

You're sitting in front of it. A PC soundcard with suitable software can generate, record, replay and display a whole range of waveforms.

In times-past I used a PC soundcard to generate CTCSS tones for 2M repeater access, to produce the two non-harmonically-related sinewaves for SSB linear-amplifier testing: there are downloadable 'test tone sets' available free from a multitude of places - you can put a lot of these on a 4Gb USB memory-stick and play them back using VLC, Audacity, Windows media Player or similar].

I also use an ancient PC as an automated "CQ-sender" on HF: just hit the spacebar and it sends 45 seconds of CQ.

I've also used a "swept tone' generated this way to explore sideband-filter passband shapes.

The soundcard input is similarly useful - you can capture audio and either record it for later analysis [this has proved useful in identifying intermittent problems which never seem to happen when you're watching the screen], use the PC as a frequency-counter, or as an oscilloscope [dual-trace if your soundcard is stereo!] to display waveforms or waterfalls.

[A waterfall is handy for identifying intermittent ultrasonic oscillations in amplifiers: I guess it could also be used tio explore wow-and-flutter on record-players/tape-decks?]

Again, even using a 'lossless' algorithm, it'll take days of capture to make a significant dent in the free-space of a modern hard-drive.

And i'd bet the accuracy of a typical soundcard's digitisation is as linear [or logarithmic if desired] as most 'scopes or signal-generators used by amateur/hobbyist repairers.


Look at your PC and see what test-gear it can replace!

[Station X]

Let's assume I have radio in front of me which needs repairing.

Firstly I'll need a set of screwdrivers to get the back off and get the chassis out of the cabinet. Might need some spanners too.

Next I'll do some basic continuity and safety checks so I'll need a DMM.

At the very least I'll snip out any capacitor across the mains supply and change the audio coupling capacitor, so I'll need a soldering iron, cutters and thin nosed pliers.

Before applying power I might want to reform the smoothing capacitors using a capacitor reformer.

I might wish to apply power via a lamp limiter, but if basic checks have been done I don't consider it essential.

With power applied I'll take voltage readings and based on the results I might have to change components. I've already got the tools for that.

Armed with the basic set of tools and test gear mentioned I reckon that around 95% of radios could be repaired without the need for anything else.