[TenTec] OT: Scopes

Mon Feb 20 13:58:10 PST 2012

Rick,
Just general questions on the voltage...If I want to look at ripple on 
a B+ I guess I'm fine up to...maybe 750 VDC with a 10x probe rated for 
that kind of voltage.
I see thay do make HV scope probes also.
73,
Lee

 -----Original Message-----
From: Rick - DJ0IP / NJ0IP <Rick at DJ0IP.de>
To: 'Discussion of Ten-Tec Equipment' <tentec at contesting.com>
Sent: Mon, Feb 20, 2012 2:17 pm
Subject: Re: [TenTec] OT: Scopes

Well you can look at it all day long (hi), but if you want to measure 
it...

I guess my question is, what are you wanting to look at when you measure
across the plate>

Measure the amplitude with a voltmeter.
Measure the signal on the other side of the capacitor.
If you are looking for things like the ripple on the DC, then be sure 
your
probe and voltmeter can handle the voltage.  To be honest, if that's 
what
you want to do, then look for a scope with 400 or 500 volt ratings, not 
250.

The safest way then would to build yourself a voltage divider with a 
pair of
resistors, and measure in between the resistors.  That way you can look 
at
the ripple without having the full voltage on your probe.

73
Rick, DJ0IP

-----Original Message-----
 From: tentec-bounces at contesting.com 
[mailto:tentec-bounces at contesting.com]
On Behalf Of kc9cdt at aol.com
Sent: Monday, February 20, 2012 7:48 PM
To: tentec at contesting.com
Subject: Re: [TenTec] OT: Scopes

Rick,
What if I want to look at the plate?
Thanks,
Lee

 -----Original Message-----
From: Rick - DJ0IP / NJ0IP <Rick at DJ0IP.de>
To: 'Discussion of Ten-Tec Equipment' <tentec at contesting.com>
Sent: Mon, Feb 20, 2012 1:30 pm
Subject: Re: [TenTec] OT: Scopes

Lee,

The RF or Audio signal from the RX stage is passed on through a
capacitor to
the next stage, otherwise you would have the high voltage on the input
of
the next stage.   Measure on the other side of the capacitor, not on the
high voltage side.

You need to consider the voltage specs of the probe, but most should be
good
for 250v.

73
Rick, DJ0IP

-----Original Message-----
 From: tentec-bounces at contesting.com
[mailto:tentec-bounces at contesting.com]
On Behalf Of kc9cdt at aol.com
Sent: Monday, February 20, 2012 7:00 PM
To: tentec at contesting.com
Subject: Re: [TenTec] OT: Scopes

I guess the real question originated from me..to Dave.....I asked about
2500 volts as a 10x question not as if I want to measure that
voltage...I know much better.
I would use a HV prove on a VTVM.
.it wasn't that we want to measure that high of voltage...just making
sure
I (we) understand the scopes max input so as not to damage it.
If it says 250 P-P and I want to measure a waveform from the plate of a
stage of a RX with plate voltage of 150 volts and I'm using a 10x probe,
I should be fine??

The question was more of a 10x probe question...are they marked with
the max voltage? Or do you have to look up the specs? What is typical?

What is realistic in practise?

Thanks,
73,
Lee

-----Original Message-----
From: Rick - DJ0IP / NJ0IP <Rick at DJ0IP.de>
To: 'Discussion of Ten-Tec Equipment' <tentec at contesting.com>
Sent: Mon, Feb 20, 2012 12:46 pm
Subject: Re: [TenTec] OT: Scopes

Dave, you can even measure 25,000 volts with it - ***ONCE IN YOUR
LIFETIME***.  	

Scopes are not foreseen for measuring high voltage.
They are for measuring signals and wave shapes, etc.

There are better instruments for measuring high voltage and in all
cases you
should be using a purpose-built high-voltage probe.

73
Rick, DJ0IP

-----Original Message-----
 From: tentec-bounces at contesting.com
[mailto:tentec-bounces at contesting.com]
On Behalf Of Dave Edwards
Sent: Monday, February 20, 2012 6:12 PM
To: tentec at contesting.com
Subject: Re: [TenTec] OT: Scopes

Another list member and I were wondering......If a scope's front panel
says max 250 volts P/P....does that mean if you
have a X10 probe, you can then measure 2500 volts...(safely)?

....Dave

On 2/20/2012 9:07 AM, kc9cdt at aol.com wrote:
> Buy from a reputable dealer not at the hamfest IF you want more
> assurance.
> Actually when you get at least a working (check it out as much as you
> can there) scope at a hamfest....being perectly calibrated in most
> cases is not critical for our work.
> That assumes you talking boat anchors, like I work on.
> 73,
> Lee
>
>
>
> -----Original Message-----
> From: Richards<jruing at ameritech.net>
> To: Discussion of Ten-Tec Equipment<tentec at contesting.com>
> Sent: Mon, Feb 20, 2012 12:00 am
> Subject: Re: [TenTec] OT: Scopes
>
>
> Please excuse me  if I missed it... but I don't recall anyone
explaining
> to the unwashed...
>
> 	What can one do to avoid getting a lemon or broken
> 	or poorly calibrated,  or whatever broken,  oscilloscope
> 	at the local hamfest ?
>
> This item is beyond my current expertise, but it may not be
> forever beyond my grasp.    How do I avoid getting stung  (other
> than to buy something new?)    What do I look for if I don't have
> my favorite Elmer on hand ?
>
> Thanks.
>
> ----------------------------  K8JHR
----------------------------------
>
> On 2/19/2012 2:06 PM, Jim Lowman wrote:
>
>> Interesting, Steve!  Your memory is much better than mine, since I
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