Binoculars & Telescopes

The short answer For many families looking for the best GMRS handheld radios, the Midland GXT3000 is a practical place to start: it comes as a pair and supports both direct communication and GMRS repeaters. Choose the Retevis Ailunce HA1G if you want a more configurable radio with IP67 protection, or the BTECH GMRS-PRO if […]

The short answer The best Baofeng GMRS radio for most first-time U.S. buyers is the UV-5G (UV-5X) in the two-radio long-antenna kit. It gives you a matched pair, an included programming cable, and room to add a local repeater when you need one. Pick the UV-5G Mini if you want two compact radios you can […]

The short answer The Baofeng UV-9G is the first waterproof Baofeng radio I’d consider for a U.S. family that already uses GMRS and expects to encounter wet conditions. Baofeng specifies IP67, and the two-radio kit gives both users the same controls. For licensed amateur operators, the GT-3WP is the simpler choice when you want documented […]

The short answer The BTECH GMRS-V2 is our starting recommendation for long range walkie talkies: it combines repeater capability, a removable antenna, and a relatively accessible price. Choose the Rocky Talkie Expedition Radio for a simpler, waterproof outdoor setup, or the Rocky Talkie Mountain Radio when your group needs license-free operation. The important distinction is […]

A Schmidt–Pechan prism is a compact roof-prism optical system that rotates an inverted image by 180 degrees so it appears upright and correctly oriented. Its folded light path keeps the entrance and exit beams nearly coaxial, which is why the design is widely used in modern compact binoculars. Quick Specifications Characteristic Schmidt–Pechan system Image rotation […]

Moxon antenna calculator: dimensions, plans, and tuning guide. Use this Moxon antenna calculator to generate the A–E dimensions for a classic 2-element Moxon rectangle from your design frequency and conductor diameter. Choose common amateur-radio bands or enter a custom frequency, then use the plans, construction notes, tuning steps, gain and radiation-pattern guidance below to turn the calculated geometry into a practical antenna.

Calculate the vertical and horizontal wire lengths for a half-square antenna, choose a corner-fed or end-fed configuration, and use the results as practical starting dimensions for building and tuning your antenna.

Calculate the wire length, side dimensions, loop height, wavelength, and quarter-wave matching section for a delta loop or other full-wave loop antenna. Enter your operating frequency, choose the loop geometry, and use the calculated dimensions as a practical starting point for construction and tuning.

EFHW antenna calculator: end-fed half-wave design and length

OCFD Dimensions, Design & Plans. Calculate the total length, short leg, long leg and feedpoint position for an off-center-fed dipole. Choose a band or custom frequency, select the OCF split, and use the results as a starting point for building and tuning your antenna.