Search results

Here is a very simple 70cms dipole from Harald PD2HFE, which uses a single piece of RG-213 coaxial cable 34 cms in length.

Examines the practical considerations and technical challenges of deploying mobile antennas for 10-meter operation, particularly for operators on the move. It addresses the inherently _lossy_ nature of shortened, loaded vertical antennas typically used in mobile configurations, encouraging hams to view these limitations as engineering challenges. The resource provides actionable advice on safeguarding vehicle electronics, selecting appropriate cabling like _RG-213_, and properly grounding antenna mounts to the vehicle chassis. Specific mounting strategies are detailed, including roof, trunk lip, and side-mounting for trucks and vans, along with their respective advantages and drawbacks. It emphasizes the importance of a robust ground plane and suggests methods for improving grounding beyond simple set screws. The article also touches on antenna choices, mentioning "bugcatchers" and "Hamstick types" as viable options for 10 meters. Furthermore, the guide transitions to stationary mobile operation, where antenna options expand significantly. It outlines how to deploy portable dipoles or 2-element beams from a parked vehicle, offering practical tips for assembly, storage, and mast guying using simple materials like a concrete block. It notes that a 5/8 wavelength height, approximately **20 feet** on 10 meters, often yields good short-skip and DX performance, even with a take-off angle above **20 degrees**.

Details a practical QRP wattmeter construction, leveraging a simplified SWR meter design by JA6HIC. The project focuses on a forward-only power measurement circuit, providing a functional instrument for RF power levels from milliwatts up to 5 watts. It maintains a 50-ohm input and output impedance, suitable for typical QRP transceivers and antenna systems. The resource includes the schematic for the "VSW" (Very Simple Wattmeter) and outlines a six-step alignment procedure. This calibration process involves using a known RF source up to 5W, setting full-scale deflection, and marking power increments. It also addresses minimizing frequency effects on readings with a 100pF trimmer capacitor, noting that measurement error is highest at the lower end of the scale. Construction notes mention using a piece of RG-213 coaxial cable for the inductance and coupler, with the wattmeter assembled in early 2003. The author provides an example measurement showing 0.8W into a dummy load and 1W into a 3-element beam.

A page with several coax cable characteristics comparison. Includes RG-316 RG-174 RG-58/U RG-59 RG-213/UBX RG-213 FOAM AIRCOM plus AIRCELL 7 ECOFLEX 10 ECOFLEX 15 H-155

The Resonant Feedline Dipole (RFD) HF antenna design utilizes a single piece of coaxial cable and a stranded wire section, forming a 1/4-wavelength radiator. This configuration, based on a 1997 ARRL Handbook design (page 20.17), functions by RF traveling on the inside of the coax shield and returning on the outside, creating the second half of the dipole. A choke wound into the feedline prevents RF current from flowing back down the feedline. Construction details include using RG-58a/u coax for a 75m version, with a 1/4-wavelength section of stranded wire soldered to the center conductor. The document provides choke dimensions for RG-213, RG-8, and RG-58 coax across 3.5 MHz to 28 MHz, specifying cable length and number of turns. Dipole dimensions are also tabulated for frequencies from 3.6 MHz to 28.4 MHz, listing overall length and individual leg lengths. Field tests included deployment near Bryson City at 5 feet off the ground and as a sloper during WCARS Field Day in Asheville, yielding successful local and regional contacts.

A loop antenna made with common RG-213 coax and rests on a cross made of 6 mm fibreglass rods anf a 6.5- 30MHz tune

The construction process of making crimp-on connectors with many pictures and instructions by VE7BZ

How to make an effective RF Choke. The coiled coax choke is the easiest to make but also the least effective. This article includes some general guidelines for winding coax chokes on a 10cm PVC pipe using RG-58 or RG-213 coax cable.

The resource provides coaxial cable attenuation data, listing signal loss in dB per 100 feet for various cable types across a frequency range from 1 MHz to 5.8 GHz. The initial table details attenuation for cables such as _RG-58_, _RG-8X_, and RG-213, with impedance values of 50 ohm or 75 ohm, at frequencies up to 1 GHz. For example, _RG-58_ exhibits **0.4 dB** loss at 1 MHz and **21.5 dB** loss at 1 GHz per 100 feet. A subsequent table expands on this data, including LMR series cables like _LMR-400_ and LMR-600, along with other types such as 9913F7 and RG214. This section covers frequencies from 30 MHz to 1,500 MHz, also noting the outer diameter of each cable. For instance, _LMR-400_ (0.405" diameter) shows **0.7 dB** loss at 30 MHz and 5.1 dB loss at 1,500 MHz per 100 feet. The final section focuses on VHF/UHF/Microwave amateur and ISM bands, presenting attenuation in dB per 100 feet (and meters) for frequencies including 144 MHz, 450 MHz, and 2.4 GHz. This table includes larger diameter hardline options like 1/2" LDF and 7/8" LDF, in addition to flexible coaxial cables. For example, 1/2" LDF cable demonstrates **0.85 dB** loss at 144 MHz and 6.6 dB loss at 2.4 GHz per 100 feet. DXZone Focus: Coaxial cable attenuation | LMR-400 | RG-58 | 5.8 GHz

Over 100 distinct RF connector types are available from AIR802, including popular UHF series PL-259 plugs and SO-239 sockets, designed for a wide array of coaxial cable dimensions. The company specializes in producing connectors compatible with common amateur radio cables like RG-8, RG-213, and RG-58, ensuring reliable signal integrity for antenna systems and shack interconnections. Their product line extends to various coaxial cable types and pre-made antenna cable assemblies, offering ready-to-deploy solutions for hams. AIR802 also provides custom cable assemblies and pigtails, catering to specific installation requirements for transceivers, tuners, and amplifiers. These pre-fabricated options simplify station setup, reducing the need for field termination of connectors. Michael Bryant is the contact for inquiries regarding their range of RF components, which are essential for building robust and efficient amateur radio stations.

Coaxial cable stripping for PL-259 connectors requires precise measurements to ensure optimal RF performance and mechanical integrity. For RG-8X, the outer jacket is stripped 1/2 inch, the braid 5/16 inch, and the dielectric 1/8 inch, leaving the center conductor exposed. RG-58 preparation involves a 1/2 inch jacket strip, 1/4 inch braid strip, and 1/8 inch dielectric strip. These specific dimensions facilitate proper soldering and crimping, minimizing impedance discontinuities at the connector interface. Different coaxial cable types, such as RG-8 and RG-213, necessitate varied stripping lengths due to their construction. The _PL-259_ connector, a common UHF type, relies on these exact preparations for a secure fit and low-loss connection. Incorrect stripping can lead to high SWR, RF leakage, and mechanical failure, impacting overall station efficiency. The guide details these critical dimensions for several popular coax cables. Using a dedicated _coax stripper_ tool or precise measurements with a utility knife improves consistency.

PRO-LINK specializes in the manufacturing and distribution of high-quality cabling solutions, including a wide array of fiber optic cables and various coaxial cable types. Their product line encompasses 50-ohm and 75-ohm coaxial cables, essential for diverse RF applications, alongside specialized RF cables and 10Base-T networking cables. The company also provides a selection of connectors and custom cable harnesses, catering to specific installation requirements. Since 1988, PRO-LINK has offered a 5-year warranty on its products, underscoring a commitment to durability and performance. The product catalog details specifications for different cable constructions, such as _RG-58_, _RG-213_, and _LMR-400_ equivalents, which are commonly used in amateur radio installations for antenna feedlines and inter-component connections. Their offerings support both commercial and amateur radio operators seeking reliable signal transmission. The company's focus on robust cable and connector solutions addresses the critical need for low-loss transmission lines in radio communication systems, ensuring signal integrity across various frequency bands.

Operating an amateur radio station effectively requires reliable coaxial cable to minimize signal loss between the transceiver and antenna. SIVA Cavi, an Italian manufacturer, produces a range of coaxial cables, including specific 50 Ohm low-loss types suitable for amateur radio applications. Their product line features cables like **RG 58 SHF1**, **RG 213 SHF1**, and **RF 400 SHF1**, which are commonly deployed in HF and VHF/UHF setups. The company also offers specialized cables such as the **HF 214 UF Ultraflex**, a high-performance broadband low-loss 50 Ohm cable designed for flexibility and reduced attenuation across various amateur bands. These cables are engineered with solid or foam dielectric materials, impacting their electrical characteristics and suitability for different power levels and frequency ranges. For instance, foam dielectric cables often exhibit lower loss at higher frequencies, a critical factor for VHF/UHF operations. Beyond amateur radio, SIVA Cavi manufactures cables for digital video broadcast, offshore marine use, and fire detecting systems, demonstrating a broad engineering capability in coaxial cable technology.

This project documents the construction of a coaxial 50 MHz notch filter to eliminate inter-band interference between 50 and 70 MHz transceivers. Using RG-213 coax and based on quarter-wave stubs, the filter achieved a 44 dB attenuation at 50.060 MHz while maintaining low insertion loss on 70 MHz. A dual-stub design broadened the notch response and minimized attenuation on 70 MHz to 0.2 dB. Fine-tuned using an FA-NWT network tester and Elecraft XG3 signal source, the filter effectively resolved interference for seamless dual-band operation.