Dr. Anton T. Squeegee said:
< Top-posting corrected. Please don't top-post! See this link for
the reason why:
http://www.html-faq.com/etiquette/?toppost
Sure. Check
http://www.arrl.org/hamfests.html for hamfests in your
area. They happen all over the country (heck, all over the world) at
various times during the year, and the swap meet portion of any
hamfest bears (usually) a 95% or higher focus on electronics in terms
of test gear, radios, computers, etc.
If you've never been to such an event in your life, I would
(SHAMELESS PLUG ALERT) take a look at an article I wrote on my own
page at this link:
http://www.bluefeathertech.com/technoid/Scrounger.html
This is a guide to scrounging at both surplus places and swap meets.
I hope you find it helpful.
Happy hunting.
It is very rare for a cross posted article to RRS to be useful. Most are
Trolls. I enjoyed your web page on scrounging. I'm taken aback on the
prices that you posted about equipment however quoted below.
Dr. Anton T. Squeegee wrote:
A TDS7104 sold new in the $30K to $40K range depending on options. I
have priced this scope at used equipment resellers in the $8 to $10K
range. The equipment is sold in calibration and working with a short
warranty like 30 days for verification that the equipment is in proper
working condition from resellers.
At prices under $1K even with no guarantees I expect this equipment is
hot at those prices. All equipment from the major makers have serial
numbers throughout the equipment and in the firmware. If you ever send
this equipment in for repair you might be in for an unpleasant surprise.
In the last few years there is a new class of scope called real time.
The reason I'm responding to this thread is that you just happened to
mention a real time scope the TDS7104. Tek calls real time scopes DPO or
Digital Phosphor scopes. Most digital scope are repetitive sampling
making them a poor choice for low frequency events like an intermittent
pulse and these are useless for high speed single shot events. The DPO's
resemble an analog scope with memory. There are the best suited digital
type for single shot or low frequently occurring events. The DPO's are
designed for a very high re-acquisition rate compared to digital
sampling types, which is why they are better suited for the low
frequency events as they are more likely to be actually sampling the
input during an event rather than being in another part of the
processing cycle. DPO's have a rapid processing cycle and also have most
of that cycle being actual sample time so they are able to catch that
infrequent pulse. The repetitive sample high speed scopes generally have
cycle times of 200KHz or slower and most of that cycle time is signal
processing and display. Repetitive sampling scopes are good at any type
of recurring signal like clocks. They are poor choice at looking at data
streams with long patterns. The only way you can look at long patterns
is at the bit level or eye mode.
