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Oak Hills Research DD-1 Digital Dial, Frequency Counter for OHR QRP Radios

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MPN:
DD-1
Condition:
Used
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$10.00 (Fixed Shipping Cost)
  • Oak Hills Research DD-1 Digital Dial, Frequency Counter for OHR QRP Radios
  • Oak Hills Research DD-1 Digital Dial, Frequency Counter for OHR QRP Radios
  • Oak Hills Research DD-1 Digital Dial, Frequency Counter for OHR QRP Radios
  • Oak Hills Research DD-1 Digital Dial, Frequency Counter for OHR QRP Radios
$99.99
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Description

Oak Hills Research DD-1 Digital Dial, Frequency Counter for OHR QRP Radios

  This unit was tested on the air with an OHR QRP radio and it works fine. So I know it will work with the OHR rigs.

Unfortunately  I do not have a manual for this unit but there is some information out there about using it with the other compatible radios.

Oak Hills Research DD-1 (also called OHR DD-1 Digital Dial / Frequency Meter) is a vintage QRP ham radio accessory: a compact 6-digit programmable frequency counter kit designed primarily as a digital dial for analog VFO-based transceivers. It provides direct frequency readout (with IF offset compensation) on rigs that originally had only mechanical dials. It doubles as a general-purpose bench frequency counter.Key Specifications
  • Display: 6-digit red LED readout (bright and easy to read).
  • Frequency Range: 100 Hz to 50 MHz (input sensitivity suitable for VFO/LO sampling).
  • Modes: Digital dial (programmable IF offset) or standalone frequency counter.
  • Features:
    • 5 programmable memory channels for different IF offsets (push-button selectable).
    • Selectable resolution: 100 Hz or 1 kHz.
    • Anti-jitter circuitry on the last digit.
    • Supports reverse tuning (oscillator tunes opposite to operating frequency).
    • Digit blanking / battery-save mode.
    • Direct frequency display with any IF offset (as long as sampled frequency ≤ 50 MHz).
  • Power: 12 VDC (low current draw; works from shack supply, car battery, or rig power).
  • Input: Samples VFO/local oscillator signal (typically via small coupling capacitor like 47 pF and phono/RCA jack).
  • Construction: Through-hole kit on a single PCB (parts well-organized like classic Heathkit; narrow pad spacing requires care with soldering). Includes enclosure, cables, and clear instructions with voltage checks.
  • Size: Compact matching OHR enclosure (roughly handheld size; sits neatly beside small QRP rigs).
  • Accuracy: Typically 10–100 Hz with proper calibration (users report excellent stability).
It works with tube or solid-state rigs that have an accessible variable oscillator up to 50 MHz. No internal modifications needed in most cases—just a simple tap to the VFO output.Compatible RadiosThe DD-1 was designed for all Oak Hills Research (OHR) QRP transceiver kits but is highly versatile as a general add-on digital dial or counter. Confirmed user compatibility (from eHam reviews and builds):
  • OHR rigs: OHR-100A (20m/40m versions), OHR-500 (5-band), CL2040 (40/20m Classic), and others.
  • Ten-Tec: Argonaut 509, T1300 series (T1330, T1340, etc.).
  • Heathkit: HW-8, HW-9 (including WARC band upgrades).
  • Others: Ten-Tec QRP rigs, FT-101 (expected), homebrew rigs, and any analog transceiver/transmitter/receiver with a VFO/LO output ≤ 50 MHz.
  • General use: Any oscillating circuit (VFO, crystal oscillator, etc.) for bench frequency measurement.
Users commonly pair it with older QRP CW rigs to eliminate dial inaccuracy, drift, or band-edge math. It adds no noticeable noise to the receiver.
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