Re: Tracing receive signal for low signal

Bob Lunsford <nocrud222@...>
 

My previous comment requires an edit. Eliminate the first
paragraph and make the comment like this:

The "10X" probe means it is ten times less likely to load the circuit
being read which is what you really want. Some 'scopes also have
an instantaneous digital reading but those tend to be relatively
expensive.

The secret is to take readings with the same techniques at all
points and do the math to interpret the readings. Then you can
come up with useful data.

Bob — KK5R

--------------------------------------------

On Sat, 1/12/19, Bob Lunsford via Groups.Io <nocrud222=yahoo.com@groups.io> wrote:

Subject: Re: [BITX20] Tracing receive signal for low signal
To: BITX20@groups.io
Date: Saturday, January 12, 2019, 12:15 PM

Use the 10K probe and take the onscreen
o'scope readings and
compensate with the readings using a
factor of 10... You can then
use the scope's vertical amplifier to
bring the reading up to a viable
trace/reading and using the scale see
what you have.

The "10X" probe means it is ten times
less likely to load the circuit
being read which is what you really
want. Some 'scopes also have
an instantaneous digital reading but
those tend to be relatively
expensive.

The secret is to take readings with the
same techniques at all
points and do the math to interpret the
readings. Then you can
come up with useful data.

Bob — KK5R

--------------------------------------------
On Sat, 1/12/19, Dave Space <davesspacebar@...>
wrote:

Subject: Re: [BITX20] Tracing receive
signal for low signal
To: BITX20@groups.io
Date: Saturday, January 12, 2019,
11:17 AM

Thanks for all the
info.  Ok trying to see if I got
this. It does look like
loading.

1x probe is
1.2k
10x probe is 8.9 Mohms

I checked the probe directly
outputting 50mv verified 50mv through
a .01uF blocking cap @
11.996MHZ
I put the generator into tp17 and
measured at tp17 and I would say less
than 5mv p-p was being
read from what I could tell.

I wasn't understanding if there is a
way to
now match this better or not?

Thanks

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