Marine band antenna for the Yaesu VX-7R
 

Hi,

I'm thinkinig to make an antenna for the marine band (156mhz) and hooked to
my vx-7r portable.

1. How could I make it to a reasonable carrying size (perhaps less than 12
inches)?

2. Is it possible to use the steel wire and put the heat shrink tube
outside?

3. Is the wire solder to the SMA core and no ground need?

Thanks,

Muskie

On Tue, 15 Mar 2005 17:23:34 +0800, muskie wrote:

Hi,

I'm thinking to make an antenna for the marine band (156mhz) and hooked
to my vx-7r portable.

1. How could I make it to a reasonable carrying size (perhaps less than
12 inches)?

2. Is it possible to use the steel wire and put the heat shrink tube
outside?

3. Is the wire solder to the SMA core and no ground need?

Thanks,

Muskie

Cool radio! How do you like it? Have you used it to work any ham radio
satellites, or copy any weather satellite pictures? How is for cross
talk? What do you think of the HF receiver? Have you copied any weather
charts off of HF with it?

Since your vx-7r is not type certified as a commercial maritime radio, you
need not worry about constructing an antenna suitable for transmitting.

Almost any antenna from a paper clip to the helically loaded rubber whip
that came with your vx-7r will receive just fine on the commercial
maritime frequencies around 156.8 MHz. If you put the antenna that came
with your radio on an antenna analyzer I suspect you would see very little
difference between the 146 MHz amateur 2M FM band, going up to 156.8
MHz for the maritime band or going down to 137.5 MHz for the polar
orbiting weather satellite band.

Yaesu lists marine band coverage as a feature. How bad can it be? What
do you want to achieve by changing your existing rubber whip?

gblair (I)
_at_ (really)
sympatico (hate)
_dot_ (spam)
ca (email)

_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/

UNMATCHED WEATHERPROOFING
The VX-7R case, keypad, speaker, and connectors are carefully sealed to
protect the internal circuitry against water damage. And the optional
CMP460A Speaker/Mic, like the transceiver itself, is rated for 30 minutes
of submersion at a depth of up to three feet!

THE BEST VERSATILITY EVER
50/144/430 MHz: 5w Power
Utilizing a reliable FET power amplifier circuit, the VX-7R provides a
full 5 Watts of power output on the 50, 144, and 430 MHz Amateur bands,
with bonus coverage of the 222 MHz band at 300 mW (USA version Only) of
power output. And for 6-meter AM enthusiasts, you also get 1 Watt of
carrier power on the 50 MHz band! Four power levels may be selected, for
optimum battery life.

Dual Receive: V-V/U-U/V-U/GEN-HAM
The VX-7R is capable of four modes of Dual Receive, including simultaneous
reception on (1) two VHF frequencies; (2) two UHF frequencies; (3) one VHF
and one UHF frequency; or (4) one "General Coverage" frequency and one
"Ham" frequency. And when a call is received on the "Main" band, you can
set up the VX-7R to reduce the audio level on the "Sub" band, if you like!

Wide Frequency Coverage
With continuous AM/FM reception coverage of 500 kHz to 999 MHz (cellular
frequencies are blocked and non-restorable), the VX- 7R is ideal for
monitoring HF shortwave broadcasts, the AM and FM Broadcast bands, plus a
wide variety of Marine, Public Safety, and Government bands. And special
memory banks for the Weather, Marine, and Shortwave bands make station
selection effortless!

_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/

I had a VX7-r, I was not impressed with it's receive capabilities on HF.
Since it is SUPPOSED to be a VHF/UHF rig I wasn't too surprized.......

"Spam Fighter" wrote in message
.. .
On Tue, 15 Mar 2005 17:23:34 +0800, muskie wrote:
Cool radio! How do you like it? Have you used it to work any ham radio
satellites, or copy any weather satellite pictures? How is for cross
talk? What do you think of the HF receiver? Have you copied any weather
charts off of HF with it?

Muskie

The answer to this is a simple one. Simply make a Slim Jim antenna using 300
Ohm feeder. Design it for 145MHz and then cut a 1" strip if metal from a
drinks can and wrap it around the antenna just above the coax feed point. By
sliding the metal strip up or down the antenna the resonant point will move
by 10 - 20MHz. I have used this design many times, you can mark the correct
point for marine band and for 2M the move the metal tuning thingy depending
on where you wish to Tx. The dimensions are not critical, I have built
several of these antennas for use on the marine band (ie too small for use
on 2m) but by sliding the tuning strip down the antenna it works great on
2m.

The antenna can be rolled up and put in your pocket when not in use and hung
from a tree any other suitable support when required. OK, it's going to be
bigger than 12" but so is a 1/4W antenna at this frequency.

Jon G2FHF




"muskie" wrote in message
...
Hi,

I'm thinkinig to make an antenna for the marine band (156mhz) and hooked
to
my vx-7r portable.

1. How could I make it to a reasonable carrying size (perhaps less than 12
inches)?

2. Is it possible to use the steel wire and put the heat shrink tube
outside?

3. Is the wire solder to the SMA core and no ground need?

Thanks,

Muskie

On Tue, 15 Mar 2005 17:23:34 +0800, "muskie"
wrote:

Hi,

I'm thinkinig to make an antenna for the marine band (156mhz) and hooked to
my vx-7r portable.

1. How could I make it to a reasonable carrying size (perhaps less than 12
inches)?

2. Is it possible to use the steel wire and put the heat shrink tube
outside?

3. Is the wire solder to the SMA core and no ground need?

Thanks,

Muskie




You can make a coaxial antenna using coax cable. Take RG-58 for
example. Cut off the outside jacket about 20 inches from the end.
Make a small hole in the shield brade and pull out the center
insulator and conductor. Cut both the center conductor and braid to
about 18 inches in length. Then tape the braid to the side of the
coax cable. Make some sort of hook on the top of the center conductor
and hook it, or maybe tape it, to a high place. The antenna will be
effectively a vertical dipole. They work great.