After selling off a prior oscilloscope nearly two decades ago, I decided
to pick up another used one. I have forgotten most of the functions.
This is a used two channel 30 Mhz Elenco S-1325. I can return if it
fails my testing.

All I did so far use a coax t adapter between an RF signal generator and
a 50 ohm dummy load to channel the remaining side into one of the scope
channels. I then set it for 28 Mhz and 100,000 uV output. After some
fiddling, mainly because I forgot most functions, I finally got a nice
sine wave of the approximate frequency. What other functions might I
perform to make sure it is functioning ok?

Thanks.

Jason Bowers wrote:
================
After selling off a prior oscilloscope nearly two decades ago, I decided
to pick up another used one. I have forgotten most of the functions.
This is a used two channel 30 Mhz Elenco S-1325. I can return if it
fails my testing.

All I did so far use a coax t adapter between an RF signal generator and
a 50 ohm dummy load to channel the remaining side into one of the scope
channels. I then set it for 28 Mhz and 100,000 uV output. After some
fiddling, mainly because I forgot most functions, I finally got a nice
sine wave of the approximate frequency. What other functions might I
perform to make sure it is functioning ok?



** You need to buy or borrow a test oscillator, function or sine /square.
Then you check each setting of the controls, one at a time.
Square waves should look "square".

Vertical calibration can be checked with the help of any DMM on AC volts and a 400Hz sine wave.
Horizontal calibration really needs a frequency counter, but the 50/60 Hz supply is very accurate .

Make sure the "trace rotation" controlactually works.


...... Phil

In article , says...

After selling off a prior oscilloscope nearly two decades ago, I decided
to pick up another used one. I have forgotten most of the functions.
This is a used two channel 30 Mhz Elenco S-1325. I can return if it
fails my testing.

All I did so far use a coax t adapter between an RF signal generator and
a 50 ohm dummy load to channel the remaining side into one of the scope
channels. I then set it for 28 Mhz and 100,000 uV output. After some
fiddling, mainly because I forgot most functions, I finally got a nice
sine wave of the approximate frequency. What other functions might I
perform to make sure it is functioning ok?

Thanks.

Does it offer combinations of two channels, e.g. A+B; A-B. Latter
differential could be checked with identical inputs and seeing how
accurately you get zero!

On 5/2/21 6:18 AM, Mike Coon wrote:
In article , says...

After selling off a prior oscilloscope nearly two decades ago, I decided
to pick up another used one. I have forgotten most of the functions.
This is a used two channel 30 Mhz Elenco S-1325. I can return if it
fails my testing.

All I did so far use a coax t adapter between an RF signal generator and
a 50 ohm dummy load to channel the remaining side into one of the scope
channels. I then set it for 28 Mhz and 100,000 uV output. After some
fiddling, mainly because I forgot most functions, I finally got a nice
sine wave of the approximate frequency. What other functions might I
perform to make sure it is functioning ok?

Thanks.

Does it offer combinations of two channels, e.g. A+B; A-B. Latter
differential could be checked with identical inputs and seeing how
accurately you get zero!


Thanks to you both. Well, all is not paradise and beginning to think
that I may return it. I could be overlooking something so looking for
some suggestions.

It seems that both frequency and voltage readings are off. I have an
old URM-25 RF signal generator that I have been feeding into it by
sampling off of the side of a t connector with one side having 50 ohm
dummy load and the other into ch 1 of the scope. Anything I've tried in
frequency and it seems like I'm reading at least double that frequency
on the scope if I count divisions from P-P. A 28 Mhz signal appears as
50 Mhz or plus on the scope. I just wonder if I'm overlooking something
here. Also, with the maximum output from the generator, 100,000 uV, I
am getting around 300,000 uV or more if I could divisions.

I don't yet have my 1/10x probes. They are due to arrive this week. I
will then immediately check the 2V P-P calibration signal on the scope
and see what happens.

Jason Bowers wrote:
================

It seems that both frequency and voltage readings are off. I have an
old URM-25 RF signal generator that I have been feeding into it by
sampling off of the side of a t connector with one side having 50 ohm
dummy load and the other into ch 1 of the scope. Anything I've tried in
frequency and it seems like I'm reading at least double that frequency
on the scope if I count divisions from P-P. A 28 Mhz signal appears as
50 Mhz or plus on the scope. I just wonder if I'm overlooking something
here. Also, with the maximum output from the generator, 100,000 uV, I
am getting around 300,000 uV or more if I could divisions.


** Using an old, tube RF gen is not the way to calibrate a scope.

You can started with known DC voltages, checked with your DMM.
Just switch the vertical amps to DC coupled.

A square wave test shows if there are response errors - in one go.
If it looks square, the response is as it should be.

I don't yet have my 1/10x probes. They are due to arrive this week. I
will then immediately check the 2V P-P calibration signal on the scope
and see what happens.

** Scope have internal trim controls for calibration.
You scope clearly works OK, it may need some adjustments to be spot on.

This would all be described in the owners manual.


...... Phil

In article , says...

It seems that both frequency and voltage readings are off. I have an
old URM-25 RF signal generator that I have been feeding into it by
sampling off of the side of a t connector with one side having 50 ohm
dummy load and the other into ch 1 of the scope. Anything I've tried in
frequency and it seems like I'm reading at least double that frequency
on the scope if I count divisions from P-P. A 28 Mhz signal appears as
50 Mhz or plus on the scope. I just wonder if I'm overlooking something
here. Also, with the maximum output from the generator, 100,000 uV, I
am getting around 300,000 uV or more if I could divisions.




Your signal generator is probably set to give RMS voltage and you are
reading peak or peak to peak voltage on the scope. There is a
conversion factor of some number I can not recall but it is around 1.4
or 2.8 times. Also some generators will be open circuit voltage and
some into the 50 ohm load with is 6 db or someother number I can not
think of right off.

Ralph Mowery wrote:
In article , says...

It seems that both frequency and voltage readings are off. I have an
old URM-25 RF signal generator that I have been feeding into it by
sampling off of the side of a t connector with one side having 50 ohm
dummy load and the other into ch 1 of the scope. Anything I've tried in
frequency and it seems like I'm reading at least double that frequency
on the scope if I count divisions from P-P. A 28 Mhz signal appears as
50 Mhz or plus on the scope. I just wonder if I'm overlooking something
here. Also, with the maximum output from the generator, 100,000 uV, I
am getting around 300,000 uV or more if I could divisions.




Your signal generator is probably set to give RMS voltage and you are
reading peak or peak to peak voltage on the scope. There is a
conversion factor of some number I can not recall but it is around 1.4
or 2.8 times. Also some generators will be open circuit voltage and
some into the 50 ohm load with is 6 db or someother number I can not
think of right off.

my signal generator outputs some wonky voltages unless you have a load
resistor across the outputs. It's 600ohms in a box with 1" spacing banana
plugs and receptacles. I could never figure out why that's not handled by
a pushbotton.

Also, make sure you don't have any knobs pulled out putting you in zoom
mode. My signal generator has one of silly scope knobs too for some
reason.

In article ,
says...

my signal generator outputs some wonky voltages unless you have a load
resistor across the outputs. It's 600ohms in a box with 1" spacing banana
plugs and receptacles. I could never figure out why that's not handled by
a pushbotton.

Also, make sure you don't have any knobs pulled out putting you in zoom
mode. My signal generator has one of silly scope knobs too for some
reason.



Signal generators are designed to put out a certain voltage into a
certain load. Think of them as having a signal generating source of
zero impedance in series with a resistor. Any load will devide between
the internal impedance and the load impedance.

For RF generators there were two standards. One was an open circuit Or
very high impedance) voltage and the other was for a 50 ohm load. My
service monitor has a software setting to do either one. It is from the
old analog cell phone days and 30 years ago the cost was about $ 50,000.
When the cell phones went digital the service monitor was put out for
surplus and are selling for under $ 1000 now on the used market.

When using a scope you have to allow for the peak or peak to peak ratio
to the RMS value of a sine wave. As mentioned before I don't recall the
ratio as I seldom need it and the scope I have now will calculate it and
put on the display. If your RMS meter shows abot 120 volts AC out of
the wall socket a scope will show around 170 volts peak.

Need some equipment.

I take a DC voltage source and then adjust a square wave generator to that voltage and go up seeing if the amplitude stays with the changing of the V/div. control. And move the position control to see if the waveform is linear at all portions of the screen.

Keep going up in frequency, I happen to have a generator that stays stable at any frequency, it is a Wavetek and operates on a different principle than most. Most do keep a square constant, but not necessarily in sine wave.

Next you need a freq counter, set the generator accurately to a 1,000Hz square, put the scope on 1mS/div. Adjusting the horizontal position to where the first cycle lines up with the graticule, check the rest. They should also line up and the vertical parts of the square wave should be on graticule lines all the way across. If they run off, the time base or H size is off. To determine which, switch to different frequencies ad time bases, always with the freq counter on it. If they vary it is the time base, if they constantly run off one way or the other it is the H sweep size - or more professionally put - deflection.

How accurate you need it depends on price. I got one I don't pay much attention to, the time base or deflection is slightly off but I am not measuring frequency with it. The amplitude reads right and that is enough because I use it for everything. Even DC, it is much quicker because usually I only need to know a source is there.

If you need a scope that is totally accurate all the way you need an old Tektronix.