diff --git a/src/app/new-contact/page.tsx b/src/app/new-contact/page.tsx
index 18a5014..26318c5 100644
--- a/src/app/new-contact/page.tsx
+++ b/src/app/new-contact/page.tsx
@@ -37,6 +37,7 @@ import { Switch } from '@/components/ui/switch';
 import { Textarea } from '@/components/ui/textarea';
 import { cn } from '@/lib/utils';
 import { frequencyToBand, AMATEUR_BANDS } from '@/lib/bands';
+import { AMATEUR_MODES, defaultRstForMode } from '@/lib/modes';
 import { gridToLatLon, distanceKm, bearingDeg, compassPoint, kmToMiles } from '@/lib/grid';
 
 void _PageHeader;
@@ -61,7 +62,7 @@ interface PreviousContact {
   notes?: string;
 }
 
-const MODES = ['SSB', 'CW', 'FT8', 'FT4', 'RTTY', 'PSK31', 'AM', 'FM'] as const;
+const MODES = AMATEUR_MODES;
 const BAND_PILLS = AMATEUR_BANDS;
 
 // QRZ XML license-class codes — used to give the chip a human-readable label.
@@ -381,20 +382,8 @@ export default function NewContactPage() {
   };
 
   const handleSelectMode = (value: string) => {
-    setFormData((prev) => {
-      const next = { ...prev, mode: value };
-      if (value === 'CW') {
-        next.rst_sent = '599';
-        next.rst_received = '599';
-      } else if (['SSB', 'FM', 'AM'].includes(value)) {
-        next.rst_sent = '59';
-        next.rst_received = '59';
-      } else if (['FT8', 'FT4', 'PSK31', 'RTTY', 'MFSK', 'OLIVIA', 'CONTESTIA'].includes(value)) {
-        next.rst_sent = '-10';
-        next.rst_received = '-10';
-      }
-      return next;
-    });
+    const rst = defaultRstForMode(value);
+    setFormData((prev) => ({ ...prev, mode: value, rst_sent: rst, rst_received: rst }));
   };
 
   const handleSelectBand = (value: string) => {
diff --git a/src/components/QuickLogCard.tsx b/src/components/QuickLogCard.tsx
index d0898d3..b54f058 100644
--- a/src/components/QuickLogCard.tsx
+++ b/src/components/QuickLogCard.tsx
@@ -20,6 +20,7 @@ import {
 } from '@/components/ui/select';
 import { cn } from '@/lib/utils';
 import { frequencyToBand, AMATEUR_BANDS } from '@/lib/bands';
+import { AMATEUR_MODES, defaultRstForMode } from '@/lib/modes';
 
 interface Station {
   id: number;
@@ -39,15 +40,9 @@ interface LookupResult {
   error?: string;
 }
 
-const MODES = ['SSB', 'CW', 'FT8', 'FT4', 'RTTY', 'PSK31', 'AM', 'FM'] as const;
+const MODES = AMATEUR_MODES;
 const BANDS = AMATEUR_BANDS;
 
-function defaultRstForMode(mode: string): string {
-  if (mode === 'CW') return '599';
-  if (['FT8', 'FT4', 'PSK31', 'RTTY', 'MFSK', 'OLIVIA', 'CONTESTIA'].includes(mode)) return '-10';
-  return '59';
-}
-
 function formatUtcClock(d: Date): string {
   const hh = String(d.getUTCHours()).padStart(2, '0');
   const mm = String(d.getUTCMinutes()).padStart(2, '0');
diff --git a/src/lib/modes.ts b/src/lib/modes.ts
index 849b828..afcd9d5 100644
--- a/src/lib/modes.ts
+++ b/src/lib/modes.ts
@@ -38,3 +38,27 @@ export const AMATEUR_MODES = [
 ] as const;
 
 export type AmateurMode = (typeof AMATEUR_MODES)[number];
+
+// Modes whose signal report is conventionally a dB SNR (e.g. "-10") rather than
+// an RST. Both logging forms carried their own copy of this list; keeping it
+// here as the single source of truth stops the two from drifting apart (and from
+// falling behind AMATEUR_MODES) as new digital modes become loggable.
+//
+// The WSJT-X / weak-signal family (FT8, FT4, JS8, FST4, JT65, JT9, Q65, MSK144)
+// genuinely reports dB. The keyboard PSK/RTTY/MFSK/Olivia/Contestia group is
+// grouped here to preserve the default Nextlog has always applied to those menu
+// entries — not because RTTY is a dB mode.
+const DB_REPORT_MODES = new Set<string>([
+  'FT8', 'FT4', 'JS8', 'FST4', 'JT65', 'JT9', 'Q65', 'MSK144',
+  'PSK31', 'PSK63', 'RTTY', 'MFSK', 'OLIVIA', 'CONTESTIA',
+]);
+
+// The signal report a logging form should pre-fill when an operator picks `mode`.
+// CW takes RST with a tone digit (599); dB-report digital modes take -10; every
+// other mode (phone, digital voice, image, packet) takes a 59 RS(T).
+export function defaultRstForMode(mode: string): string {
+  const m = mode.trim().toUpperCase();
+  if (m === 'CW') return '599';
+  if (DB_REPORT_MODES.has(m)) return '-10';
+  return '59';
+}
diff --git a/tests/modes.spec.ts b/tests/modes.spec.ts
index 5c34248..75692c4 100644
--- a/tests/modes.spec.ts
+++ b/tests/modes.spec.ts
@@ -1,5 +1,5 @@
 import { test, expect } from '@playwright/test';
-import { AMATEUR_MODES } from '@/lib/modes';
+import { AMATEUR_MODES, defaultRstForMode } from '@/lib/modes';
 
 // The mode list is the canonical set of operating modes Nextlog can store, and
 // the single source of truth the contact-search mode dropdown draws from. These
@@ -54,3 +54,54 @@ test.describe('modes module', () => {
     expect(AMATEUR_MODES.slice(0, 4)).toEqual(['SSB', 'CW', 'FT8', 'FT4']);
   });
 });
+
+test.describe('defaultRstForMode', () => {
+  test('CW gets a 599 signal report', () => {
+    expect(defaultRstForMode('CW')).toBe('599');
+  });
+
+  test('phone modes get a 59 signal report', () => {
+    for (const mode of ['SSB', 'AM', 'FM']) {
+      expect(defaultRstForMode(mode)).toBe('59');
+    }
+  });
+
+  test('digital dB-report modes default to -10', () => {
+    // WSJT-X / weak-signal families report a dB SNR, and Nextlog has always
+    // defaulted its PSK/RTTY/MFSK/Olivia/Contestia menu entries the same way.
+    const dbModes = [
+      'FT8', 'FT4', 'JS8', 'FST4', 'JT65', 'JT9', 'Q65', 'MSK144',
+      'PSK31', 'PSK63', 'RTTY', 'MFSK', 'OLIVIA', 'CONTESTIA',
+    ];
+    for (const mode of dbModes) {
+      expect(defaultRstForMode(mode)).toBe('-10');
+    }
+  });
+
+  test('preserves the exact classification the logging forms used before centralizing', () => {
+    // The two logging forms each carried their own copy of this heuristic; the
+    // shared helper must not change the default for any mode they both handled.
+    expect(defaultRstForMode('CW')).toBe('599');
+    for (const mode of ['FT8', 'FT4', 'PSK31', 'RTTY', 'MFSK', 'OLIVIA', 'CONTESTIA']) {
+      expect(defaultRstForMode(mode)).toBe('-10');
+    }
+  });
+
+  test('digital-voice and image modes fall back to 59', () => {
+    for (const mode of ['DMR', 'DSTAR', 'C4FM', 'YSF', 'M17', 'FREEDV', 'SSTV', 'PACKET', 'ATV']) {
+      expect(defaultRstForMode(mode)).toBe('59');
+    }
+  });
+
+  test('is case-insensitive', () => {
+    expect(defaultRstForMode('cw')).toBe('599');
+    expect(defaultRstForMode('ft8')).toBe('-10');
+    expect(defaultRstForMode('ssb')).toBe('59');
+  });
+
+  test('returns a default for every canonical mode', () => {
+    for (const mode of AMATEUR_MODES) {
+      expect(['59', '599', '-10']).toContain(defaultRstForMode(mode));
+    }
+  });
+});