Tek 7904 scope

It's been a while since I used any 7000-series stuff [1] but IIRC the timebase to look for is the 7B92A. It's a dual timebase, you can use one timebase to delay the other (which is very useful) and it only takes up one slot in the 'scope. [1] There was a 7904 and an assortment of plugins in the lab where I did my Ph.D. I was the only person ever to use it, really, everybody else thought it was very old-fashioned. It was, but it's a darn good 'scope. I'd like one for home in some ways _but_ they are full of custom silicon and Tektronix no longer supply spares. If a chip fails you've got problems... Well, if you want to look ot the output of a 70 cms transmitter (which is about 430MHz, at least in the UK), you really want to be able to see at least the 3rd harmonic. Which means going up to 1.2GHz+. However, the most useful instrument IMHO for setting up a transmitter is an RF spectrum analyser (then you can see just what you're shoving out out-of-band). Yes, you can get spectrum analyser plug-ins for the 7904 (they have 7Lxx modul numbers, where xx varies with the band they cover), but you want to be sitting down when you hear the price!. I have the 1S1 sampler (and cathode follower probe [2]) in my old 500-seires 'scopes. That give a 1GHz capability, and I have used it (when setting up the local oscillator of a 2m receiver, for example). These sampling modules essentially work by aliasing the signal down into the passband of the 'scope and thus only work for repetitive signals. Fine for looking at a carrier (or local oscillator) signal, not so useful for other things. [2] An active probe with a tiny triode valve inside. -tony