Mercurial > whatever / changeset

--- a/content/10MHz_ref.rst	Sat Mar 19 00:50:44 2016 +0100
+++ b/content/10MHz_ref.rst	Sat Mar 19 00:53:20 2016 +0100
@@ -3,10 +3,10 @@
 ==========================================
 
 :author: David Douard
-:date: 2016-02-21
 :Category: Electronics
 :Tags: test equipment, 10MHz, Rubidium
 :series: 10MHz Bench Reference Standard
+:series_index: 1
 
 Many electronics test equipment need an accurate time base. Most
 often, it's build on a 10MHz base.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/10MHz_ref_2.rst	Sat Mar 19 00:53:20 2016 +0100
@@ -0,0 +1,57 @@
+==========================================
+ Building a bench 10MHz reference: part 2
+==========================================
+
+:author: David Douard
+:Category: Electronics
+:Tags: test equipment, 10MHz, Rubidium
+:series: 10MHz Bench Reference Standard
+:series_index: 2
+
+This is a quick follow-up of the `first part`_ of this series.
+
+I've received a few parts from digikey, including a couple of 22µH
+Sumida CLS62 inductors (I bought two of them in case I f**k up one of
+them trying to solder it with my Weller WS50 iron).
+
+Desoldering and soldering SMD parts without an air flow station is a
+bit tricky, but eventually I succeded in replacing the broken inductor.
+
+.. image:: {filename}/images/freq_ref/extron_fixed.jpg
+	   :alt: The Extron Video Distribution Amplifier fixed with a
+                 new inductor for its small DC-DC converter.
+
+Now the "video" amplifier works like a charm. The 10MHz signal is
+nicely amplified:
+
+.. image:: {filename}/images/freq_ref/extron_working_10MHz.jpg
+	   :alt: The Extron Video Distribution Amplifier dispatching a
+                 10MHz signal to several equipments.
+
+At 10Mhz, the amplifier dephase the signal of about 20ns (ie. 72
+deg). We can also note that (the input impedance of the Extron
+amplifier is set to 75 ohm, while my scope is at 1 Mohm; I should try
+using the input of my scope set at 50ohm) that the amplification
+factor is exactly x2.
+
+.. image:: {filename}/images/freq_ref/extron_dephasing_10MHz.jpg
+	   :alt: The Extron Video Distribution Amplifier dephasing at 10MHz.
+
+What I need to check carefully now is if all the outputs of the
+amplifier are perfectly in phase.
+
+It's amusing that a few days ago, FlyingHacker_ did post a `new thread
+on the EEVBlog`_ forum in which he explain that he uses exactly the
+same distribution amplifier to provide a 10MHz reference to several
+test equipments. Exactly what I have in mind with mine!
+
+One thing I will probably not do is adapting the input/output
+impedance (from 75 ohm to 50 ohm). I'm pretty sure it will work fine
+as is. We'll see if it provoque some side effects (especioally on the
+phase of the signal).
+
+.. _FlyingHacker: http://www.eevblog.com/forum/profile/?u=110591
+.. _`new thread on the EEVBlog`: http://www.eevblog.com/forum/projects/distribution-amp-%28for-reference-frequency-standard-or-otherwise%29/msg893851/
+
+
+.. _`first part`: {filename}/10MHz_ref.rst

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