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Mods.DK serves as a central repository for **amateur radio modifications**, offering a substantial collection of user-contributed articles. Hams can find detailed instructions for various equipment, from transceivers by Yaesu, Kenwood, and Icom to microphones and power supplies. The database, currently holding 6230 articles, facilitates searching for specific equipment modifications, such as enabling out-of-band receive and transmit capabilities or integrating high-speed packet modems for enhanced data communications. Many entries focus on achieving better performance from existing gear, often detailing how to expand frequency coverage for MARS/CAP operations or optimize radios for 9600 baud packet. The site also includes repair instructions and general improvements for a wide array of HAM rigs and modems, reflecting a community-driven effort to share technical knowledge. Users are cautioned that modifications are not verified by Mods.DK and are undertaken at one's own risk, with potential legal implications depending on local regulations. The platform emphasizes community support, encouraging direct contact with authors or forum discussions for troubleshooting.

Mars Mod for Yaesu FT-450 extending frequency range: 1.8-30 MHz

MARS CAP Mod for TS-570

IC‐2300 MARS/CAP mod expanded frequency range 136‐174 MHz

The Icom IC-7300 is a popular HF transceiver among amateur radio operators, known for its advanced features and performance. This modification guide focuses on enabling extended transmission capabilities, specifically for MARS and CAP frequencies. The instructions are based on the work of PA2DB and include detailed steps for removing specific diodes to unlock additional frequency ranges. Before proceeding with the modification, users are advised to take necessary precautions, such as ensuring the radio is powered off and using ESD protection. The guide emphasizes the importance of using appropriate soldering techniques and tools to avoid damaging sensitive components. A video demonstration is also provided to assist users visually in performing the mod. While this modification can enhance the functionality of the IC-7300, it is crucial to note that it may void the warranty and should be undertaken at the operator's own risk. The guide serves as a valuable resource for those looking to expand their operating capabilities with this versatile transceiver.

by Steve Hicks N5AC and Jim Boehner N2ZZ

This modification will expand the tx frequency range of the Yaesu FT-991 from allowing just ham radio bands, to all bands 1.8 - 30MHz and 50-54 MHz.This information is solely for use by licensed members of MARS (Military Affiliate Radio System) or CAP (Civil Air Patrol)

Problem width the memories, TS-570 Batteries, MARS/CAP Modification

Kenwood TS-450S/TS-690S MARS modification video

Kenwood TS 990S, Military Auxiliary Radio System modification

Marshall G. Emm, N1FN, meticulously examines iambic keying, dissecting its historical introduction in the late 1950s with transistorized electronic keyers and its purported advantages. The resource defines keying systems, electronic keyers, and various paddle types, including single-lever and dual-lever paddles, clarifying the distinction between iambic keyers and the iambic sending technique itself. It details the two main types of squeeze keying: true squeeze for alternating dot-dash strings and character insertion for specific elements within a character. N1FN critically evaluates the actual efficiency gains of iambic keying, referencing Chuck Adams, K7QO's, keystroke analysis. While a straight key to bug transition yields a 34.1% reduction and a bug to non-iambic keyer offers 16.1%, iambic keying provides only an 11% theoretical improvement. However, considering typical QSO text and Morse code's inherent optimization for common letters, the practical efficiency gain is estimated at a modest 4-6%. The article also highlights how iambic keying's reliance on precise timing gates can impose a speed limit, making it less effective above 40 WPM, where many operators revert to non-iambic methods or single-lever paddles.

MARS modification instructions for the Yaesu FT-450D

Doing the MARS Mod on the TS890S. This will take care of any of your HF or Mars needs, and any new bands added in the future. You will now have the new 60m Band also. It is unclear if it will open up the 4m Band that some EU Countries are now allowed.

Presents two distinct hardware modifications for the Icom IC-7300 transceiver, detailing the necessary steps for each. The first modification, a _MARS_ transmit expansion, involves the physical removal of specific surface-mount diodes (D422) from the main board, enabling transmit capabilities across a broader frequency range, including out-of-band frequencies. It specifies the diode location on US versions of the IC-7300 and suggests using small diagonal cutters if a soldering iron is not preferred or available. The second modification focuses on the internal antenna tuner, aiming to provide wider impedance matching capabilities. This involves adding a **100k ohm** resistor to a designated point within the tuner circuit. The resource also briefly mentions a microphone modification for the _HM219_ and a general power increase, though without specific instructions for the latter two. It emphasizes safety precautions, such as disconnecting power and inspecting the work area.

Over 200 distinct 2-meter band amateur radio repeaters are cataloged for Australia, providing essential operational data for VHF communication. Each entry specifies the repeater's output frequency, often including the input tone (e.g., **91.5 Hz** or **123.0 Hz** CTCSS) and the repeater's callsign (e.g., _VK2RSC_, _VK3RHF_). Locations are precisely noted, frequently referencing specific towns, mountains, or geographical features such as "Kinglake, Kangaroo Ground" or "Adaminaby, Mars Hill." The resource also indicates various digital modes and linking capabilities where applicable, such as "FMEchoLinkFusionWIRES-X" or "DMR," alongside standard FM operation. This detailed listing facilitates local and regional VHF communication, enabling hams to program their transceivers accurately for repeater access. The data is presented in a clear, tabular format, making it straightforward to identify repeaters by frequency and location.