hf freq

118 links

Choking balun for 160-30 meter band - Choking balun for lower HF and MF bands. (1.8MHz - 10MHz). Requiring a choking balun to isolate the potential RF pick up on the coax cable as it runs past equipment such as computer within the radio room at lower HF and MF frequencies a simple method of winding RG58 coax onto a Powdered Iron Toroid Core was constructed.
[ Hits: 196 | Votes: 3 | Rating: 6 ]

VHF Log Periodic Antenna - 17-Element Very High Frequency/Ultra High Frequency Log Period Dipole Array
[ Hits: 1246 | Votes: 7 | Rating: 5.86 ]

Tuning Antenna Traps - The problem with making your own trapped HF antennas is usually getting the coaxial traps tuned to frequency. This article explains a method using a RF signal generator at +10dBm output into the coaxial trap.
[ Hits: 276 | Votes: 2 | Rating: 6.5 ]

Long Wire Antenna for portable operations - With the view to establish a quick and easy multi-band antenna deployment for portable and camping operations a simple long wire antenna with an earth or earth plus counterpoise arrangement with a 9:1 voltage unun including a tuner or simply with a tuner is one possible solution. With the 9:1 voltage unun and wire lengths suggested in the below tables the antenna should present non extreme impedances for all HF amateur band frequencies. This page is far from complete and represents the ongoing investigation into this type of antenna. Experiments to date seem to have raised more questions than obvious answers.
[ Hits: 804 | Votes: 13 | Rating: 8.69 ]

Collins 618F-1A VHF Aircraft Transceiver - Restoring a 1965 Collins 618F-1A VHF aircraft radio. This radio was designed for light aircraft as an early frequency-synthesized radio built in 2 separate chassis.
[ Hits: 313 | Votes: 2 | Rating: 10 ]

Hofi - Hofi Hochfrequenztechnik, RF switches, antenna tower and antenna manufacturer, owner of the versatower and fritzel brand names based in Germany
[ Hits: 352 | Votes: 2 | Rating: 6.5 ]

HF Bands - A review of the HF ham radio bands, considere by far the most popular bands in the amateur service. HF bands offer local QSOs and world-wide propagation are all possible at almost anytime with careful selection of the right frequency for the time of day, time of year, and current state of the sunspot cycle.
[ Hits: 372 | Votes: 1 | Rating: 10 ]

Ham Radio: Using Repeaters - The most basic form of repeater receives communication on one frequency and re-transmits at a different frequency. This is known as duplex communication. Repeaters are generally set up to operate with FM modulation on the amateur bands within the VHF (30 MHZ – 300 MHZ) and UHF frequencies (300 MHZ – 3 GHz). These are generally the frequencies used by handheld and mobile devices.
[ Hits: 92 | Votes: 1 | Rating: 8 ]

Using a Baofeng handheld to work Satellites - How to program Baofeng handheld transceiver with satellite frequencies, and how to get alerts when satellites are visible by using a smartphone app. A beginners guide to work satellites with a common VHF handheld radio.
[ Hits: 545 | Votes: 5 | Rating: 8.2 ]

HF communication prediction tools - Online HF Communication prediction system provided by the Australian Governament Buerau of Metereology allow to predict usable frequency rage for radiocommunications between two stations allowing to specify frequency and date range. This tool allow calculation with different methods and algorithms
[ Hits: 169 | Votes: 0 | Rating: 0 ]

Maldol MFB-300 HF vertical antenna review - The Japanese-made Maldol MFB-300 HF vertical antenna offer extremely wide-band performance, with a specified frequency range of 1.0-60 MHz.
[ Hits: 434 | Votes: 2 | Rating: 5.5 ]

TYT MD-2017 Review - The MD-2017 is a dual band DMR and Analog handheld transceiver with a frequency range on VHF 136-174 MHz and on UHF 400-480 MHz
[ Hits: 319 | Votes: 3 | Rating: 4 ]

Icom IC-2300H Modification - IC‐2300 MARS/CAP mod expanded frequency range 136‐174 MHz
[ Hits: 2080 | Votes: 12 | Rating: 6.08 ]

Marine VHF Frequencies - The following table is adapted from the International Telecommunications Union Radio Regulations Appendix 18, including changes adopted by the 2012 World Radio Conference.
[ Hits: 820 | Votes: 1 | Rating: 6 ]

FT CALC 1.3 - Ferrite Toroidal Core HF Calculator - This EXCEL Program Worksheet calculates the safe operating conditons for a toroidal transformer operating between 1 and 50 MHz. Manufacturer data for complex permeability, magnetic dimensions, and saturation flux density must be available. Some core types which are commonly used in amateur transmission are included. The program produces limiting winding voltages for linear operation and temperature rise over the range of frequencies and power specified.
[ Hits: 283 | Votes: 1 | Rating: 2 ]

How to Design an RF Power Amplifier - This video will provide a foundation for understanding how power amplifier circuits work. If you are new to High Frequency Power Amplifier Circuit Design, this is the place to start.
[ Hits: 674 | Votes: 1 | Rating: 10 ]

VHF-UHF Diplexer - Diplexer is a passive device, a special filter circuit that seperates 2 different bands, not to be confused with the duplexer that usually separate 2 different frequencies on the same band.
[ Hits: 1140 | Votes: 2 | Rating: 5 ]

Experimental HF 6-band SSB transceiver - An SSB radio for the HF bands will be presented. Featuring 12 to 20 Watts of output power (depending on DC supply), full DDS frequency generation, covering 6 major frequency bands (1.8, 3.5, 7, 14, 21 and 28 MHz) within the short wave amateur radio spectrum. The rig also features colored LCD and front panel backlight.
[ Hits: 709 | Votes: 14 | Rating: 9.86 ]

Cross Band Repeaters - Crossband Repeating is a process where a Ham transmits one signal on one band (typically UHF), and it is received by another radio with a better antenna/power installation, and re-transmitted (typically on VHF) to another radio system, or a repeater. Everyday examples of cross-band repeaters are repeater receive sites that hear the input signals on 2m and retransmit those signals on a frequency higher than 220 MHz.
[ Hits: 207 | Votes: 0 | Rating: 0 ]

Antuino - Antenna Test Equipment - Antuino is an accurate instrument that can be used in the field to measure SWR, field strength, modulation, etc. In the lab, it can be used to sweep filters, measure gain, distortion, frequency response, etc. It works upto 150 Mhz. On the third harmonic, it is usable on 435 Mhz band as well (with reduced sensitivity).
[ Hits: 305 | Votes: 0 | Rating: 0 ]