Yaesu VX-7R

The Yaesu VX-7R is a quad band 50 MHz (6 meters), 220 MHz (1.25 meters), 144 MHz (2 meters) & 440 MHz (70 centimeters) handheld amateur radio transceiver with extensive receive coverage, and leading-edge features.The radio's magnesium alloy case is available in black anodized or silver (clear anodized). The model number suffix "B" or "S" denotes which color, black or silver respectively.

The radio is designed to operate in extreme conditions, and is sealed against water and chemicals, making it well-suited for emergency-services duty. Available accessories include remote microphones, earphones, barometric pressure sensor module, and adapters for digital communications modes.

The VX-7R can be programmed directly from the integral keyboard, or using a computer, linked by a cable which connects to the speaker/microphone connector. There are several free and inexpensive programs available with which to modify settings.

The DTMF memories allow strings of DTMF tones to be stored, allowing it to be conveniently used in a "remote-base" system with a radio such as the TS-2000.

Feature overview

* 900 Memories
* Wideband receiver, 500 kHz - 999 MHz (the US version has cellular telephone frequencies blocked)
* CTCSS/DCS tone squelch
* European Tone Burst
* True user-selectable Dual Receive
* ARTS-Automatic In-Range Transponder
* Backlit Keypad & LCD
* Internet Key for Access to WIRES
* DTMF encoder for control of remote systems and telephone dialing
* Sensors for temperature, voltage (internal battery or external power source), real-time clock, and barometric pressure (optional module)
* User-definable icon images for bands, S-Meter glyphs and font characters
* Waterproof (3 foot depth for 30 minutes)
* 132 x 64 pixel back-lit dot matrix display

elected specifications

Receive:

Frequency Range Transmit:
* 50 - 54 MHz – 5 Watts
* 144 - 148 MHz – 5 Watts
* 222 - 225 MHz – 300 mW (US version)
* 430 - 450 MHz – 5 Watts

Each band (except 222 MHz) can be switched between 5 watts, 1 watt, 300 milliwatts, and 50 milliwatts.Through an undocumented test menu, it is relatively easy to change power output within ~10 milliwatts to 5 Watts for each power level. This is useful because the small battery will last significantly longer at 2.5 Watts than 5 Watts (about 1/2 current drain for a very small reduction in range). Newer Vx-7r models seem to have the power outputs set to 50MW, 1W, 2.5W, 5W instead of the old 5 watts, 1 watt, 300 milliwatts, and 50 milliwatts.

Characteristics

* The VX-7R can transmit a 1 watt AM carrier on the six meter band. While the usefulness of this feature is disputed, it is fun to try. It is recommended to use an external antenna tuned to the lower part of the six meter band for this feature.
* The VX-7R is often used for FM voice communications through low earth orbit amateur radio satellites.
* The VX-7R cannot transmit and simultaneously receive on another band as some other "dual-receive" HTs can, but the dual-receive on any combination of bands functions reasonably well. The "Sub" VFO is limited to frequencies around the 50, 144, and 440 amateur bands, while the "Main" VFO has a much broader frequency coverage.

Modifications

The VX-7R can be modified to transmit on MARS and CAPS frequencies through both hardware and software techniques. The hardware modification requires the removal of small solder contacts located under the battery pack. The software modification can be made with the VX Commander software through a data interface cable. Both modifications obtain the same result, except that the software modification will be disabled if the radio is hard-reset.

Soon after the release of the VX-7R a design flaw was discovered related to the radio's waterproof housing. Not only was the radio water-tight, but it was also air-tight. This would result in a pressure differential between the inside of the radio and the atmosphere, caused by changes in barometric pressure or altitude. This pressure differential would prevent proper oscillation of the speaker diaphragm, resulting in reduced and muffled audio output. Yaesu remedied the problem by adding a small valve under the bottom left rubber armor, which allows equalization of the interior pressure with the atmosphere. The design change was reflected in all new radios produced from that point on, and any older radios sent in for repair are retrofitted with this modification.

Some VX-7R owners complained of poor microphone sensitivity, which resulted in low audio levels on transmit. A crude modification was developed by end-users to solve the problem, at the expense of sacrificing the radio's water-proof capability. If small holes are pierced in the rubber seal covering the microphone diaphragm, then sound waves can better reach the microphone diaphragm, resulting in better audio sensitivity.

References

*cite journal |title=Yaesu VX-7R Handheld Tranceiver Product Review |journal=QST |publisher=ARRL |location=Newington, Connecticut |date=October 2002

External links

* [http://www.yaesu.com/ Yaesu's Home Page]
* [http://groups.yahoo.com/group/VX-7R/ VX-7R on Yahoo! Groups]
* [http://www.egr.msu.edu/~volzmich/radio/vx7/ Fixes for low microphone audio and intermittent receive audio]