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Yaesu VX-7R

Handheld Ham Transceiver

           

 

 

 

 

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The Yaesu VX-7R is a slick, compact 11.5cm by 6.5cm handheld transceiver with a rugged diecast case and rubberized corners. It is completely waterproof. It offers a rather useful barametric pressure module in addition to the temperature sensor. It is capable of up to five watts of FM transmit power on VHF and UHF and receives signals which range from the AM broadcast band and shortwave through to one gigahertz. It uses LiIon battery technology which gives about three days of barometric sensor usage, and about two days of receive usage, and about a day of two-way usage.

Why did I buy it?

I bought this as a device which I could take back country canoeing and remain in touch, as it were. Other licenced radio amateurs (hams) within about 20km are able of holding two-way communications with me. That is the unit is cabable of 5 watts of FM in VHF and UHF bands.

The question that many ask: why spend a thousand dollars Canadian on each VX-7R (with options) when you can get a pair of FRS walkie-talkies for less than 25% of that cost? Well, how much is life worth? Does your survival ever depend on your being able to communicate more than a kilometer? Will your well-being ever be jeopardized if the FRS unit gets wet? Remember, FRS units are usually only capable of 10% of the transmit power of the submersible VX-7R, and that is not even factoring the latter unit's military grade robustness. Leave the FRS to the kids. It's usually worth spending a bit more for dependable communications equipment, especially when far from home.

The other reason I bought this is for shortwave receive coverage. I used to carry along a Grundig YB-400 which did very nicely for early morning and late evening portable shortwave coverage and it was also a good alarm clock. The VX-7R does a fine job on the shortwave coverage, but is not a good alarm clock. It is also a small fraction of the size of the YB-400 and add to that the wetness of backwoods camping factor and the rationale for using the Yaesu becomes quite clear. The point to note, however, is that you do need a long wire antenna for the VX; do not expect to use the rubber duck that comes with it for short wave. I pack along the Grundig roll-up antenna and connect it via alligator clip to the tip of the rubber duck. The duck gets very poor shortwave reception without such help.

Primary Capabilities

The primary intent of the VX HT is for triband operation, 6m, 2m, and 70cm. Seemingly as an afterthought, they added low power transmit capability for the 1.25m (220mhz) band. It does a reasonable job as a portable, but has some significant shortcomings.

Shortcomings

The built-in microphone is characterized by low audio -- even with your mouth about a centimeter from the unit, you need to be talking in a rather loud voice to avoid "low audio" complaints from other hams.

I took the unit to the place I bought it, Radioworld, and they confirmed that everything was "in spec". It was explained that the waterproof membrane which encases the unit also prevents the microphone from being as sensitive as it otherwise might be. It also helps mute the background noise, mind you. However, if you are depending on fringe communications, you do need to get either an external microphone, or you need to bone up on your shouting techniques.

The other significant downside with this unit is that it is very prone to interference problems. For example, I cannot take it near my 17" CRT based computer monitor without getting full scale noise on 2m. When the monitor goes into low power mode, the problem is greatly reduced, almost eliminated. I normally keep the HT two to three meters away while working on the computer. Or, I switch to my Apple iBook.

The CRT is just one source of interference. During the business day, between mid-morning and about nine o'clock at night, there is the frequent sporatic bursts of digital traffic that can take it anywhere from S2 to S9. It gets so bad, that I often have to just shut the thing off. Interestingly, it tends to be far worse when I am in the basement, than when I am outside the house. I keep most of my computers in the basement. Again, this is on 2m; there is none of that on 70cm.

To alleviate the interference problem I needed to enable the front end attenuation feature, which was easy enough to do via the built-in menu system. This nearly eliminated the intermod related problems. When in the country, I just disable attenuation to reclaim the receiver sensitivity.

The interference rejection problems make the VX-7R somewhat less than ideal for metropolitan use in the VHF bands. If all you want is two meter coverage and you don't ever have moisture problems, then the VX is not for you -- specialized 2m units tend to have fewer interference problems and are less expensive. The VX is excellent, on the other hand, for metropolitan use in the UHF 70cm band.

For trips into the back country, on the other hand, the VX-7R is hard to beat. If you are hiking, climbing, or canoeing, this is an ideal unit for the members of your party to be carrying. Remember though, VHF/UHF communications are line of sight. If you have high mountains or huge distances between communicating parties, VHF/UHF is less than ideal. For longer, more remote trips, you need to consider factors like range and intervening terrain. For emergency communications in the Canadian tundra for example, you might want to consider something which supports shortwave (HF) transmissions due to the intervening distances. HF transmissions require additional authorization beyond the Basic Amateur Radio Licence.

Options

Since each charge will only get you a couple days of light usage, you also will need to take spare batteries. A spare LiIon battery pack (FNB-80LI) will set you back just under CA$200 with taxes. And if you have multiple LiIon battery packs, you probably want to consider getting the optional desk charger (CD-15A). The desk charger does its job independant of the VX transceiver, and is faster than the AC adaptor that comes with the base VX-7R package.

For about CA$50 (taxes in) I picked up a battery holder which enables you to use a pair of standard AA batteries (FBA-23). These permit several hours of receive and limited low power transmit (up to 1 watt). Using a pair of freshly charged NiCad AA cells, you can figure on about four hours of receive capacity. If you use alkaline AA cells, you can expect to get about a day. If you consider that four AA cells weigh approximately as much as the LiIon pack, you would need to pack a lot of AA cells. If you depend on two-way radio coverage, then you better figure on taking a couple of spare charged LiIon packs, rather than depending heavily on the AA pack and a bag full of cells.

The LiIon packs can be charged while in the car, whilst attached to the VX-7R, using optional cigarette lighter adaptor E-DC-5B. This is in fact the recommended approach while mobile. The alternative is to use a (third party) power inverter and the desk charger. Inverters do tend to be quite inefficient, but if short charge times are more precious than your 12v lead-acid car battery, then these can be quite handy. I use an auxillary battery in my van so that I never risk discharging the battery used for the engine -- a diode permits the auxillary battery to be discharged independent of the main battery.

To handle the marginal audio problem, I ended up getting the earbud/microphone combination (VC-27). This is very lightweight and gives a decent improvement to transmitted audio. The earbud not only improves your ability to pickout faint signals, but reduces demand on the audio amplifier, extending battery life. The earbud/microphone combo was about CA$70 taxes in.

The waterproof nature of the VX-7R means that it can be splashed and it can be rained on, and it doesn't matter. At other times, however, the problem is dirt. If you find this applies to your situation, you do want to get the vinyl case (CSC-88). It was CA$35, and for back woods operation it is recommended. The PTT and the DTMF controls operated well through the clear plastic front of the case. There are a few limitations when using the Yaesu supplied case. For example, the case will prevent the VX from swinging freely on the belt clip -- though it will still be somewhat usable. Also, the case provides no protection for the tuning/volume coaxial control at the top of the unit.

If extended trips into the back woods, into the fringes of VHF/UHF coverage, are planned, you should probably get a better antenna than the basic rubber duck -- you can improve the signal by several db. Many of these antennas come from other manufacturers and use BNC connectors rather than the SMA connector used by the VX-7R. The CA$15 BNC to SMA adaptor is part number CN-3.

The barometric sensor unit is part number SU-1 and is recommended if you are a weather buff, or you take the VX-7R hiking, or canoeing. The cost for this was about CA$60 which included installation. The Yaesu documentation notes that this is not intended as a replacement for a proper professional quality altimeter. But, it can be used as an altimeter nevertheless. If you have never used an altimeter, you need to visit your local library to read up on how to use one, otherwise you can expect frustration. The unit supports nicely millibar units as well as american inches.

The barometer and temperature readings are only displayed when the transceiver is turned off. As such, back lighting for the display will not be available. Keep a penlight handy. Also beware, after using the transceiver you need to have it turned off for a least five minutes before reasonable barometric readings are possible -- the initial values are skewed and must not be relied upon. Keep this in mind when configuring the barometric pressure offset -- get it right the first time, and if you don't wait a few minute before you try again. You can expect calibrate it monthly using a high quality stationary barometer and get reasonably accurate results, though I calibrate mine a couple times a year using a nearby online weather station. The temperature sensor requires considerably longer than five minutes -- fifteen minutes to an hour.

Some Hams use their HTs to get their e-mail via packet radio. I can offer no experiences though I do note that the manual does make reference to such modes.


 

 



va3xto@rac.ca
Copyright © E. J. Ritzmann.
Last Change $Date: 2003/04/19 15:58:47 $

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