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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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20th Jul 2017, 11:14 pm | #21 |
Heptode
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Re: Test equipment: how much is needed?
Don't forget the humble headphone/capacitor combination. Used with the "finger" or "short wire aerial" injector, many simple radio faults can be found.
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20th Jul 2017, 11:43 pm | #22 |
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Re: Test equipment: how much is needed?
It all goes back to #5. Test equipment is largely a matter of personal preference. You can get by with almost nothing and still do a good job. If you're used to using some sort of fancy kit or other, you'll feel it's practically indispensable.
Of course, there are many areas of modern electronics where it's effectively impossible to work on equipment without lots of (modern) professional workshop gear, but that's not what this forum is about. |
21st Jul 2017, 1:15 am | #23 | |
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Re: Test equipment: how much is needed?
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For the signal generator you need two basic types. One for audio frequencies and another well calibrated type for radio frequencies, which also has modulation options if you want to properly repair and re-align radios. For TV's you require pattern generators. I have a well equipped workshop now, but when I started as a child, all I had for test apparatus were things like light bulbs, a crystal earpiece (which can resolve audio and with an added diode demodulate audio off an RF carrier) and a dodgy multi-meter. It is surprising what you can get away with. For example with a light bulb placed across a device like a car's fuel injector, you can brightness match another bulb to it from a DC source and from the DC level work out the duty cycle of the injector, just as one example. But there is an old saying that still applies: The best piece of equipment in the workshop is the thing between the ears. |
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21st Jul 2017, 4:31 am | #24 |
Octode
Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
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Re: Test equipment: how much is needed?
How much is needed?
To which my response is "How much is needed.....for what? I am amused to see that virtually everyone who has replied so far has assumed that there is only one job for test gear - namely to repair some bit of faulty kit. And on this list - that will usually be a broadcast radio. If that is the only job you want to do and you define "working" as "it makes a noise", then you can fix such radios with no more than a soldering iron and a bit of know how. You can replace the burnt out discoloured resistors, and the bulging electrolytics just by looking for them. And with some luck you then have it making a noise again without any test gear at all. You can then go on to roughly align it just using broadcast signals and a screwdriver. That is a very long way from what I do with electronics. Firstly I define "working" as "it meets the spec". And to check that - you are usually going to need a pile of test gear. Certainly a signal generator - if it's a receiver - and probably an audio power meter to check power output. If it's hi-fi, you will probably want to check distortion levels. That's going to place a whole new set of demands on your kit. Merely "making a noise" can be a very long way from "it meets its spec." If it's a professional communications receiver, it's liable to have specs for spurious responses, IF selectivity and the like. And for that, you will probably need quite a high spec professional signal generator - not a cheapie from Maplin. Something more like a HP8640B. If you start checking specs like 3rd order intermod, you will almost certainly need 2 generators - and possibly 3 - depending on the exact test you want to do. If you then move to transmitters, you will almost certainly need a means of measuring RF level against frequency - and while you can do that with a calibrated receiver - more likely you will use a spectrum analyser, plus probably filters, dummy loads and attenuators. Other people have mentioned scopes. I don't find them that useful for receiver work - but of course they can be used in a number of places. And they become more or less essential if you are working on things like synthesisers, or logic circuitry. The other big differentiator is going to be design work as opposed to fixing work. One can reasonably assume something that needs fixing did actually work to spec at one point in time. And if its returned to its "as built" state with all working components it should again meet its spec. With new circuitry you have just designed there is no such certainty. You may need a raft of test gear then to work out why a circuit does not do what you thought it would. Or just to check that it meets the spec you set yourself. So of course its a "horses for courses" sort of question. And depending on what you are doing you may need nothing at all - up to an array of kit that would normally only be found in professional labs. Richard |
21st Jul 2017, 7:14 am | #25 |
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Re: Test equipment: how much is needed?
This is one of those bottomless discussions without any frame of reference as to what the initial question means. Rather like those school debating society "Does the end justify the means?" questions.
The replies inevitably contain information only about the reply-writers' assumptions because there was no real information in the question. David
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21st Jul 2017, 8:16 am | #26 |
Dekatron
Join Date: Nov 2010
Location: Oxford, UK.
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Re: Test equipment: how much is needed?
As David says, it depends on what you are doing. I have my own one-man-band business, of late mainly project management, but also analogue circuit design. As such I do a lot of component characterisation and have a large amount of equipment to that end. Also cable and connector characterisation over a range up to 20GHz - ditto.
There is something of a collector in this too - the ability to buy stuff (mainly, but not uniquely Tektronix) that I used in the lab in the 70's and 80's that were a house mortgage at the time essentially for beer money now. But no worse than collecting valved radio sets, period TV's or wind up gramophones. So far removed from fixing radios (although I have, and fixed, a decent RA17 rig) and TV's. Craig |
21st Jul 2017, 11:14 am | #27 |
Heptode
Join Date: Jun 2010
Location: Zurich, Switzerland
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Re: Test equipment: how much is needed?
Jeremy wrote:
HTML Code:
So I agree that you really do need to understand the limitations of your test gear and any test procedures that use that piece of test gear. Than, RF-probes & HF oscilloscopes/probes dont have 1/10Mohm input resistance/impedance, and they will/can have a variance in frequency too! Karl Last edited by karesz*; 21st Jul 2017 at 11:19 am. |
21st Jul 2017, 12:39 pm | #28 | |
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Re: Test equipment: how much is needed?
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So, yes, it is a philosophical discussion - and like many philosophical discussions, there is no defined 'end point'. I have read with much interest the comments made to date: my thanks to all who have contributed. Al. |
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