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Understanding Gain differences, j-pole and end-feed vertical antennas. -
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A re-usable control & computing platform for antenna measurement, PSK31 digital modems, audio filtering, signal source & VFO, memory keyer by AMQRP -
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If you have space constraint at your QTH for a HF antenna, you can try contructing this HF magnetic loop antenna for 40-20 meters bands -
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A 2W 80 meters transceiver assembled into a toaster case. -
You can make your own 2-meter "rubber duckies" that will likely perform much better than many commercial units. -
The document is a technical guide on designing RF filters for radio frequency applications. It covers topics such as interference suppression, band-pass filters, and low pass filters, with a focus on filter design and circuit filters. -
A combination of Fldigi and Flmsg for portable devices running Android used for NBEMS -
Paddles made from readily available materials, like double sided PC board material and cost almost nothing to build. -
Specialized amateur radio club devoted to the pursuit of operating and technical excellence in radio contesting -
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Adventures in amplified GPS antenna construction; an experiment -
Why twinlead isn't necessarily a low loss feed line. -
The Collins TRC-75 autotune linear amplifier, owned by JF2SVU, is presented with a focus on its internal modifications. This QRO amplifier utilizes three 4CX250 tubes in parallel for its final stage, delivering 1 KW output power. Notably, the amplifier achieves full power with only 100 mW of RF input, a characteristic often associated with Collins designs. The original 400 Hz power supply has been converted for easier shack integration, and the entire RF and power supply sections have been rehoused into a compact, clean enclosure. The control unit, positioned above the amplifier, features three meters for individual vacuum tube IP monitoring and a multi-meter on the right. A dedicated 7 MHz receiver, recently completed, is also part of this integrated system. The autotune functionality means the main amplifier unit only requires connections for power, control, and coaxial cables, simplifying its operation. Key components like the 4CX250 tubes and NF capacitors are visible, along with the gearing mechanism for the final tank circuit. A timer and relay system manages high-voltage delay and cooling fan off-delay, although the cooling fan's airflow is noted as somewhat insufficient. A central volume control, which experienced a contact issue, is also highlighted. -
A group dedicated to the HF Kenwood Transceiver TS-590 S -
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6m (50Mhz) Long wire antenna There is another form of long wire antenna which provides uni-directional coverage and is easy to build. Description by Arnie Coro CO2KK -
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The simple and safe RS232 CAT interface for Yaesu FT-1000MP, FT-1000MP Mark V and FT-1000MP Mark V Field rigs -
Minimal interface circuits for receiver and transmitter audio, also for PSK31 -
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Cheap UHF antenna plans for 2 meters and up including 421 1296 and 902 Mhz -
Antique Radios for Sale, Old Radios Repaired, Reproduction Parts and CD's -
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Ham Start, starter kit. Stugy guides, resources, exams, upgrades and morse code. A guide for beginners and license upgraders, Resources for getting started and advancing in ham radio (USA) -
This is a design for a stealthy HF multi-band vertical wire antenna using a tree as a supportby G7AQK -
Build An Inexpensive Repeater Controller from a Basic Stamp 1 or 2 By Roger Cameron -
A 40/80 meters dipole made with two loading coils based on a project by IK1ZOY -
PTT and soundcard interface schematic by ON6MU -
Towers by Tashjian, Engineering, Design and Manufacturing -
The G5RV multiband HF antenna, designed by Louis Varney (G5RV) in 1946, is a popular compromise antenna offering good overall performance on most HF bands when paired with an external antenna tuner. The basic full-size G5RV measures 102 feet across the top for 80 through 10 meter operation and is fed at the center via a 34-foot low-loss feed-stub. This interaction between the radiating section and the feed-stub facilitates matching across 80-10 meters with a standard tuner, often eliminating the need for ladder line directly to the shack. The antenna's design center frequency is 14.150 MHz, configured as a 3/2-wave dipole on 20 meters, with its 102-foot length derived from long-wire antenna formulas. Construction details emphasize the matching section, which can be open wire, ladder line (window-type), or TV twin lead. Each type has a specific velocity factor (VF) affecting its physical length for an electrical half-wave on 14 MHz; for instance, open wire requires 33.7 feet (VF 0.97), ladder line 31.3 feet (VF 0.90), and TV twin lead 28.5 feet (VF 0.82). The article provides formulas for calculating these lengths and discusses the antenna's behavior on individual bands, from 3.5 MHz where it acts as a shortened dipole, to 28 MHz where it functions as two three-half-wave long-wire antennas fed in-phase. Practical construction notes include recommendations for vertical descent of the matching section, sealing the coax junction, providing strain relief, and winding a coaxial choke coil to mitigate common mode current. The resource also presents dimensions for double-size (204 ft) and half-size (51 ft) G5RV versions, along with their corresponding matching section lengths for various line types, making it a versatile reference for hams considering this classic wire antenna. -
The Top-Rated Electrical and Electronic Engineering Calculator for Palm OS -
Modifications for the Kenwood TS-940, TS-940S LCD Clock Display Erratic Operation, Talk Power Improvement, erratic display, ALC mod -
Setting up a Raspberry Pi as Remote Server for RTL2832u SDR -
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FT-817 compared to FT-100 and review -
A well documented article about construction and analysis of a horizontally polarized halo antenna for 6 meters band by Dr. Carol F. Milazzo, KP4MD -
A trapped dipole antenna based on the orignal W3DZZ antenna design resonating on 80 40 20 15 10 meters -
The BayCom-Mailbox is an amateur radio/citizen band AX.25 Bulletin Board System with AX.25 store and forward capabilities. The software is available for Linux, DOS and Win-NT. OpenBCM is opensource and freeware. -
An interesting homebrewed gamma match feed for a Halo Antenna -
This article describes the antenna for Low Frequency Beacon. It originally appeared in the "Lowdown" for Oct. 1999. -
Shortened vertical antenna for 40 meters band an homebrew project -
The main purpose of the county hunter's net is to facilitate the operations of those hams seeking to work all counties in the United State. It is also a useful place for CW emergency communications as there is almost always someone monitoring the frequencies. -
RTL-SDR is a very cheap software defined radio that uses a DVB-T TV tuner dongle based on the RTL2832U chipset. This is a blog about rtl-sdr, software defined radio and their developments and applications. -
Class C tuned VHF power amplifier for the 6-meter band by ON6MU -
My MMPRINT utility is a post contest tool that lets you extract statistical data from a CT log file -
