Re: Recommend a O'scope...


<Chief_Billy@xxxxxxxxxxx> wrote in message
news:1141676401.442314.20950@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I've decided I want an o'scope for basic amp work. I'm sceptical of
Ebay offerings and need some advice as to sources for used scopes. I
know I don't need much capability to t-shoot a guitar amp, but what
would you determine to be the bare necessities. I was considering a Tek
2235 for $150; I have no idea what a used scope is worth.I want the
dual-trace feature, but I know 100 Mhz is beyond my needs.

Well, I bought a 2236 option 14 that I bought new for about $2500 at the
time. I've used it ever since for bench work. Now, I see them selling on
EBay for $100 to $200. A fine scope. This was the 2235 plus a built in
digital voltmeter, ohmmeter, time counter, and frequency counter, the option
14 was a high accuracy time base for the frequency counter. It is all
solid-state (except the CRT). I also have a temperature plugin probe for ie.
The regular probes were special, for the model, with tighter tolerances so
that the digital voltage section would be accurate. I had some of the older
Tektronix in the 500 series, all tubes, much larger, heavier, and more
likely to give problems.

When I bought the 2236, my primary business was servicing electronic musical
instruments, including Rodgers church organs. The 20mHz scope that I had
before just wasn't getting the job done any more. 100mHz is a bit of
overkill, but with prices as low as they are, why not go for it. I have
used this scope during the past couple of months in troubleshooting a HP
Distortion Meter and one of my two Trace-Elliot bass amps.

I have over 250 purchases of various things (mostly computer and electronic,
though including bass amps, speaker cabinets, and test equipment) on EBay.
I've only been burned once completely - guy never shipped a couple of 8"
hifi speakers - EBay did yank his account. There have been two other times
that merchandise was not in the described condition - both sellers took
action (in one case, ordering and paying for the Cisco Enterprise software
for the switch, in the other, paying for additional RAM for a notebook
computer) when I politely notified the seller of the discrepancy. The first
Distortion Meter that I bought (a B&W) I never did get fixed - the seller
had accurately described it, and its problem, I just had more than expected
difficulty in getting a 1K linear dual pot to fix it at a reasonable price,
so I bought a used HP Distortion Analyzer for about what I would have spent
for the pot. It didn't work, but the repair was simple, a shorted capacitor
across the meter. I don't just look at the numbers of their feedback - I
read their feedback on more expensive items.

Other sources - most other sources are going to be commercial test equipment
houses that sell used equipment. Most of these houses tend to sell only
equipment that their techs have gone through and calibrated - at much higher
prices than the usual EBay prices.

I hope that my descriptions above are helpful in your decision on getting
the Tek 2235.

Jim



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