[Radio Wrangler]

From time to time suitable scopes crop up on here, modern-ish basic ones being cleared out by educational establishments. Pocket money prices are usual, a small fraction of the going price of a second-hand 405.

You could try a post in the wanted section of this site. People grow out of their first scope and go looking for something a bit higher performance and feature rich, so there may be basic ones sitting around unused.

If a fancy one turns up, you can use it, but you'll need someone to tell you where to park all the controls for the features you aren't going to use. There's plenty of help on here. It's analogous to you showing a beginner how to do something basic on a big desk. These are the controls you need, park those like this, and all those other channels don't have mikes on them... A friend had the job of running Soundcraft for a while until H-K pulled the plug on them.

1) You'll need a couple of 'times ten' scope probes to go with it. They allow you to probe around in whatever you're testing in a non-intrusive way, and get the signal into the scope.

2) Couriers don't handle packages well enough to move scopes safely. I think they score 10 points for a rugby conversion, 3 points for a touchdown. The people on the forum move stuff around gently for each other in an informal way. Look up FCS - forum courier service and you'll see what happens.

3) High end or low end, the trip-ups for the unwary in fixing solid state amplifiers are the same. The posh amp with discrete transistors may be easier to get bits for than the power modules that infested the cheapies and the mid range stuff of the last few decades. The 405 is a well trampled path, all of its weaknesses are well documented. Much better to work on than a lot of the esoteric stuff where manufacturers guarded service info like the crown jewels, and sanded the type numbers off of transistors and ICs. Quad were open about their circuitry, they even (Walker and Albinson) wrote an article explaining it for Wireless World. Quad still exist and will fix your amp if you want them to.

You might not need a scope often, but you'll find a lot more things you can do, not only because of having a scope, but also because of the things you'll learn from one.

David