I've been accumulating a range of gear for my PhD project. Here are some of the things I use and like!
I bought and built a digital L/C meter kit from Almost All Digital Electronics. It seems to work very well! It's more expensive than some pre-built L/C meters, but claims to be accurate, was fun to put together, works down to very low values, and for some reason I didn't think to just buy a cheap L/C meter at the time I ordered it.
I bought a vintage Philips PM3320A DSO but was disappointed to find that its voltage measurement was a bit dodgy. It works okay for signals but I don't trust the vertical scale at all, and doesn't seem to be capable of even registering DC signals. Fixing it is way beyond my expertise and servicing it would cost more than the unit did! I have purchased a Rigol unit based on recommendations from the EEVblog. It has only a 100 MHz bandwidth as opposed to the 200 MHz of the Philips, but it should make up for this by actually working, and the higher frequencies are probably better examined with a spectrum analyser anyway, since my project is dealing with CW RF signals. Oh, and the sample rate is much better.
It turns out that (one of the many) problems with the Philips is that my probe was 100x and the DSO assumed 1x. It's necessary to use a special in-line probe setting thingy that uses an extra pin to the side of the BNC connector. I have not yet figured out what sort of resistor I need to add to make it recognise my probes. However even when using a BNC cable with the default 1x mode and 50 Ohm internal termination, triggering is broken unless I use Auto mode and there are sampling glitches.
A 250 MHz vector signal generator. I don't have a manual for it so I have no idea how to use the vector signal generation modes, but that's okay because I'm really only interested in CW signals at the moment! For this it works great, though it is enormous and heavy. Note, I just found a HP 8782B manual, which is very similar and will be very helpful if I ever need to use vector modes.
Sadly, the signal generator has now died :( I've pulled it apart and gone through the service manual, but most of the paths lead to 'replace the xx module'. I'll poke around at it when I can, but without a circuit diagram or more detailed servicing notes, I don't hold out a lot of hope for now. I've now supplemented it with..
A charmingly old fashioned 160 MHz synthesised signal generator. The frequency range is just right for what I'm doing, but unfortunately the output amplitude control is just a pot that goes from +3 to +13 dBm. I probably need to build/connect it to a programmable step attenuator so that I can do about -90 to +13 dBm. Otherwise, it's been great so far.
A 3.5 GHz spectrum analyser and its 2 GHz tracking generator, which I picked up on eBay for about $1600. The manual for the R4131, which is functionally similar is available on the Advantest site. Not quite as sexy as the R&S FSH3 spectrum analysers in the lab at uni, but it's very handy to have one on hand at all times. The TR4131 has a GPIB interface that can dump out memory trace data, which would be much more satisfactory than photographing the screen. Making a USB-GPIB adaptor seems very straightforward and could be fun! However buying a Prologix one certainly saved me a lot of trouble.
My friend Mick had a garage sale and I bought his GSM test set. While I have little interest in testing GSM devices (though setting up my own base station would be fun, if only I had a compatible test SIM), this bad boy earns its space on my bench by being a 1 GHz spectrum analyser (though with a pitiful span), a 1 GHz signal generator with digital attenuation control, an audio signal generator, and an audio oscilloscope.
Thanks to some PayPal promotion (I have a like-hate relationship with them) I picked up a cheap "898D" hot air rework station from eBay. These seem to be rebranded under a variety of names. Hot air is great! For removing surface mount chips it's great, though I had to increase the temperature from the default 300 to 350 (lower might be okay too) because I kept ripping tracks off while levering the components. Pushing rather than levering might have also been a good. Anyway, I think I'll use it on all surface mount ICs from now on. I soldered a SOIC8 chip by hand but found that I'd applied solder to the tops of the leads, but none had made it through to the pads below and they were mostly open circuit. Instead, flux and add a little solder to the pads, position the IC, heat, then squash and nudge into place. I like to use a small piece of aluminium foil with a square cut from the middle with a scalpel to mask surrounding components. This works great for otherwise troublesome QFN parts, though as always it's necessary to inspect with a magnifying glass. The soldering iron bit is also nice. I like that it is very light and thin and has a fine tip, but unfortunately it's a little bit naff. The heating element is a structural part of the barrel, so excessive lateral pressure will cause it to break. There's a sleeve over the base of the element that I think is too long, so I may shorten it so that the barrel's screw collar thingy goes all the way down, which should hopefully remove some of the potential for flex. Anyway, just don't try to push big things around with the tip of the iron.
The Australian distributor of the PulsarProFX PCB prototyping system, who are incredibly helpful and friendly. I had some reasonably good success with the Press 'n Peel system that Jaycar sell, but PulsarProFX claims to be superior and can also be used for solder masks (though it's not an intended use) and documentation (silk screen) layers. Success reports as they come to hand. My printer is a Kyocera FS-1000, which works well enough but I fear its resolution may not be quite high enough for the smaller SMD parts. It's proved more than adequate for 0805 and 0603 sizes, though. The verdict - it's pretty good, but with very small features such as TSOP, QFN and differential pairs, I found that my printer smudged a bit in one direction and the green TRF remained in between tracks and pads. Ahmad from Ultrakeet suggested using a piece of not-too-sticky tape - rub it on the affected area and pull it off very slowly and it'll remove the gunk and hopefully not the toner. I found that the stickiness of sticky tape could be reduced to useful levels by sticking it to my pants a few times to pick up some fluff.
Incredibly cheap PCB manufacturing in China makes the idea of etching at home a bit less appealing, but it's still handy if I need something in a hurry or am feeling very inspired.
Ah, the parts business has now been moved to Doug Ford Analog Design.
I typically buy things at Jaycar if they're commonplace or RS or Farnell if they're a bit more obscure (both have an amazing free overnight shipping service for things that are in stock locally). For prototyping it's nice to have stacks of typical passive components. The ones you want are typically stocked internationally at RS. Jaycar doesn't sell any ceramic SMD capacitors at all. The solution - eBay! You can get stupid cheap SMD resistor and capacitor kits, delivered to your door for half the price of a Jaycar SMD resistor kit. No idea what the quality is like, but you'd probably be insane to use them in production. Unfortunately inductor kits aren't as readily available.
A company I've had success with is Design Easy Electronics. Their inductor kits are reasonably priced and come in a wonderful binder. I'm in the process of getting hold of some empty binders from them so that I can put my large collection of SMD parts in them for easy access, as well as some 0603 resistors and capacitors. 0805 just seems way too big these days. Anyway, Design Easy Electronics have wonderful customer service and are a real pleasure to deal with. They sell on eBay but if you have a bit more time or can speak Chinese, it's much cheaper to get things from their Taobao store.
Should be your first stop for all RF-related products. Used by hams and in high-end Tektronik test equipment. Staff are very friendly and the products aren't too expensive, considering how unique they are and how much time they can save.
While the likes of Seeed Studio and iTead Studio have reduced the cost of PCB manufacture to the point where it's a no-brainer to have things made, even for basic one-off projects, for more complicated designs I've had great success with PCBCart. While they're nowhere near as cheap for small runs, for anything with four or more layers where you want to specify the stackup, they're excellent. Board quality is great and their customer service is superb - they've picked up and queried silly errors that I didn't notice.
A vendor of inexpensive RF connectors and cables in China. Pay a fraction of what you'd pay at element14 or similar. Super nice people, too!