Lots of old HP453's for 50 bucks are around....George



Patrick Turner wrote in message
...


TubeGarden wrote:

Hi RATs!

I use an old Heathkit OL-1 - 3" diameter round display, 500Kcycles,
single
trace.

Works great. Was $40.00, with manual, at antique mall years ago.

Happy Ears!
Al

Alan J. Marcy
Phoenix, AZ

PWC/mystic/Earhead

I am using a Labtech solid horror, one channel has ceased,
and the input attenator pot on the other has gone dodgy.
The cowboys in Taiwan forget they are making test gear,
and think thay are making low grade consumer electronics....

Then I have a collection of dysfunctional CROs, some SS and a couple of
tubies,
and one day, when I get desperate, I will restore the oldest which has a
5"
dia screen,
and is tubed, to make it give wider BW.
Trouble is, I'd have to get the Labtech to work to do the work,
since I'd need a CRO to fix another CRO.

Dual trace is nice for phase comparisons,
and for very approximate measurements of distortion 3%,
where you have the input wave on one channel, just filling the screen,
output on the other, just filling the screen,
then you add them, null out the fundemental by fine adjustment and display
the
difference,
which is the distortion. The amplitude of the distortion is then a
fraction
of screen height, say one division line, and you have say 20 divisions,
so thd = 1/20 = 5%.

Also not bad for sweep response, but I don't have a good sweep,
with calibration "pips" or markers at certain frequencies,
so the display can be interpolated.
For transfer curves, using a triangular input wave
with nice straight sides will show you what linearity you have.
bends to the straight lines indicate distortion, and or phase shift.

So I get by with a single trace CRO. Its 20 MHz, full of
14 pin chips and disctrete parts, and is difficult to service.
I once put a pulse of 2,000 volts into it, and blew most of the chips and
many

transistors, and it cost $400 to fix, more than I paid for it, as a second
hand item.

Patrick Turner.