From 1a0dad31d924cfeaa5f98100eff24f36623d5131 Mon Sep 17 00:00:00 2001
From: Denis Chevalier <perso@denischevalier.fr>
Date: Fri, 7 Aug 2026 23:34:44 +0200
Subject: Start writing specification

---
 mechanical-specifications.typ | 69 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 mechanical-specifications.typ

(limited to 'mechanical-specifications.typ')

diff --git a/mechanical-specifications.typ b/mechanical-specifications.typ
new file mode 100644
index 0000000..37c9893
--- /dev/null
+++ b/mechanical-specifications.typ
@@ -0,0 +1,69 @@
+#import "@preview/unify:0.8.1": qty, qtyrange
+
+= Mechanical specifications <mechanical-specifications>
+
+== Modules <modules>
+
+=== Cassette <cassette>
+
+==== Shielding and construction <shielding-and-construction>
+
+To achieve metrologic tier precision, modules must be fully shielded from
+external interference. The only entry points for noise are:
+
+- The DB-25 and BNC connectors at the rear, which connects via a shielded cable
+  to the power distribution board
+- The banana jacks at the front panel, which include input protection circuits.
+
+Modules must also not pollute neighboring modules with internally generated
+noise (such as PWAM oscillators). For this reason, all modules are enclosed in
+individual steel cassettes.
+
+We chose steel instead of aluminum, as it has better shielding properties,
+especially in terms of magnetic shielding.
+
+#figure(
+  table(
+    columns: (auto, auto),
+    table.header([*Parameter*], [*Value*]),
+    [Material], [DC01 cold-rolled steel (EN 10130)],
+    [Thickness], [$qty(1.2, "mm")$],
+    [Finish], [Matte black powder coard (RAL 9005), all surfaces.],
+  ),
+  caption: [Cassette construction parameters],
+) <table-cassette-construction-parameters>
+
+==== External dimensions <cassette-external-dimensions>
+
+#figure(
+  table(
+    columns: (auto, auto, auto, auto),
+    table.header([*Dimension*], [*Value*], [*Tolerance*], [*Note*]),
+    [Panel height],
+    [$qty(177.8, "mm")$ ($qty(4, "U"), qty(7, "inch")$)],
+    [$plus.minus qty(0.1, "mm")$],
+    [Full rack unit height],
+
+    [Grid pitch],
+    [$qty(38.1, "mm")$ ($qty(1.5, "inch")$)],
+    [N/A],
+    [Theoretical center to center spacing. Two columns of banana jacks ($qty(0.75, "inch")$ grid).],
+
+    [Panel Width],
+    [$qty(38.0, "mm")$ ($qty(1.5, "inch")$)],
+    [$+0.0 "/" -0.1 "mm"$],
+    [Undersized to accomodate paint thickness and thermal expansion.],
+
+    [Body height], [$qty(165.1, "mm")$, ($qty(6.5, "inch")$)], [$plus.minus qty(0.1, "mm")$], [Fits between rails],
+
+    [Body width], [$qty(38.0, "mm")$ ($qty(1.5, "inch")$)], [$+0.0 "/" -0.1 "mm"$], [Same as panel],
+
+    [Depth], [$qty(152.4, "mm")$ ($qty(6, "inch")$)], [$plus.minus qty(0.2, "mm")$], [Front to rear],
+
+    [Lip height], [$qty(6.35, "mm")$ ($qty(0.25, "inch")$)], [N/A], [Top and bottom],
+  ),
+  caption: [Cassette external dimensions],
+) <table-cassette-external-dimensions>
+
+The panel lips extend above and below the cassette body to fill the full
+$qty(4, "U")$ rack opening while the body fits between the chassis rails.
-- 
cgit