Lot of Hijacking going on here, the thread belongs to the OP who posted it.

 

"I picked up my digitising HP 54501A (100 MHz, quad channel) from a used test equipment store nearby me. (They do exist!) It cost £150 including one probe, that was about $200 back then. Have a look around for one. It's been very useful and after dusting it out, it works well."

Holy mackerel. That is a good deal fer sure. I laid out quadruple the price of your rig, to order a puny dual-trace 30Mhz 'scope whose main redeeming value is that it happens to be new.

 

"I picked up my digitising HP 54501A (100 MHz, quad channel) from a used test equipment store nearby me. (They do exist!) It cost £150 including one probe, that was about $200 back then. Have a look around for one. It's been very useful and after dusting it out, it works well."

Holy mackerel. That is a good deal fer sure. I laid out quadruple the price of your rig, to order a puny dual-trace 30Mhz 'scope whose main redeeming value is that it happens to be new.

There are a few limitations though - it's not perfect.

Only has a 10 MS/s real time sampling rate, effectively limiting single shot bandwidth to about 1 MHz. But I don't look for transients often, so it doesn't. Also, it only has two ADCs, channel 1+2 share an ADC, as do channels 3+4. You can just use channels 1 and 4 to overcome this. And the refresh rate is limited to 60 Hz. But other than that, it's a brilliant scope: almost everything about it is precisely engineered. You can set the trigger in 100µV intervals, and it WILL trigger on such a difference. It even has pattern and state analysis triggers, plus a video trigger (extremely useful for my OSD development.) It will measure a clock at at least 300 MHz if not more, although voltage readings are no longer accurate. So, very nice, and for a very agreeable price.

I was very pleased when I opened it up to clean it out (it had started to over heat so I needed to get rid of the dust.) The power supply was an example of over-engineering for the better:

The number of capacitors in it is amazing...

So, all I can do is highly recommend old digitising scopes. If I were to upgrade, I would go for a HP 54600B, as those have a higher sampling rate and refresh rate.

 

You did luck out on that buy, Tom, without a doubt. Good deals like that don't show up often. Also, I wouldn't have thought that an overheating problem could be resolved simply by cleaning out dust. Good thing you did that yourself, as a repair shop would likely have charged a small fortune for the same easy fix.

 

You did luck out on that buy, Tom, without a doubt. Good deals like that don't show up often. Also, I wouldn't have thought that an overheating problem could be resolved simply by cleaning out dust. Good thing you did that yourself, as a repair shop would likely have charged a small fortune for the same easy fix.

The store I went to had hundreds! A room with scopes just stacked one upon another - along with signal generators, logic analyers, spectrum analysers... you name it, and if it's 10 years or older, they had it. A Tek dual channel 150 MHz analog scope for £120! (I was seriously considering that one, but the digital quad channel won me over for the extra £30 and slight drop in bandwidth.) Old military, education and corporate surplus mostly, all in good condition. The scope I bought was cal'd in '06; I voided the calibration by opening it. (Doesn't really bother me anyway, it seems accurate enough.)

Also, I bought my power supply from them. £45 bought a 0-35V 0-3A CC/CV power supply. A Tagasaki power supply, made in Japan. Has a massive transformer in it and weighs a ton. It is a "GM035-3"; interestingly, it was apparently cheap because of a simple typographical error at the factory - it was supposed to be called "TM035-3", and as T and G are very close on a typical QWERTY keyboard, I can see the plausibility in that explanation.

 

... I need a real scope
oh well, one year and I'll have access to all the equipment I could ever want

 

Well Tom you have just described an electronics hobbyist's equivalent of a toy shop. I would probably wind up buying way more than I could reasonably afford in such a place, after spending a few hours just wandering the aisles, checking out the gear.

Maybe when next I'm in the UK, I might send you a PM asking where that used electronics shop is located. In the meantime I had better start saving up ha ha.