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Author Topic: Diamond NR-770SA for an HT  (Read 1108 times)
K3DC
Member

Posts: 88




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« on: November 23, 2008, 06:49:27 PM »

Are HT after market HT antennas designed with the idea
that the ground plane is poor?

I bought an Alinco DJ-596MKII at a ham fest and
it has the dummy load attachment.  I picked
up a Diamond NR-770SA from a parts bin for $2.  The
diamond is a PL-259 antenna designed for mobile mounting.
It is rigid, in tow parts and has a one turn coil
in the middle connecting the two parts.  

Typically I would go buy a whip but the Alinco is my
loaner and backup.  Could I simply use the Diamond
and get performance similar to a whip?

At Dayton i saw a guy selling whips made with BNC,
plastic tubing and CAT-5 cable.  The plastic tubing
housed the CAT-5.  I think he used 1 pair that was
shorted at the top and bottom.  I was thinking about making on of those for the fun of it but have had no suck luck searching for ideas on the Internet.

73,
ki4ymd
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WB6BYU
Member

Posts: 13043




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« Reply #1 on: November 23, 2008, 07:12:01 PM »

There isn't much complicated about making a quarter wave whip:  you
just need about 19" of any sort of wire or other conductor that will
stay more or less vertical while you wave the radio around.  I have an
antenna that is probably similar to what you describe and it is a single
piece of stranded hookup wire inside a somewhat stiff plastic sleeve.
The wire connects to the center pin of the antenna connector, and that
is all there is to it electrically.  (Mechanically there is some sort of strain
relief that reinforces the mechanical joint at the base.)

You can make your own with a piece of about #16 solid copper wire.
That should be stiff enough to stand upright without being too heavy.
If you have some stiff tubing to put over it, slide it all the way into the
BNC connector then fill the opening with hot melt glue.

With a combination of the full quarter wave whip and a radial wire hanging
down from the ground side of the antenna connector the HT is far more
efficient than using the rubber duckie.

To answer your other question about sticking a mobile whip on the HT,
it will depend on the antenna design.  For example, a 5/8 wave whip is
NOT a good idea on an HT because the angle of radiation will be too
high.  But anything that is a quarter wave or so, or a half wave design
(like the old AEA HotRod HT whips) will probably work.  One limitation
is the mechanical stress on the antenna connector:  it isn't uncommon
for the locking nut on the BNC connector to work loose when there is
a lot of stress on the connector, which isn't always an easy fix on many
of the compact HTs.
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N8EKT
Member

Posts: 371




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« Reply #2 on: November 24, 2008, 07:36:46 AM »

I'm sure your mobile antenna would work just great but one hard bump and you could be looking at a very expensive radio repair after the BNC is broken off.
There are many good dual band HT antennas.
Most are a 1/4 wave, 5/8 wave, or 3/4 wave design thus require a groundplane to operate properly.
But they are lighter weight and much more flexible.
A half wave electrical design is by far the best for handhelds since the lack of a ground plane produces poor performance in both 1/4 wave and 5/8 wave designs by comparison.
Larsen sells a 2 meter 1/2 wave telescopic KD142MHW
with a BNC on it for about $29 dollars.
And Larsen also makes a 1/2 wave 440 antenna, the KD14HW2for a little less.
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KD4LLA
Member

Posts: 450




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« Reply #3 on: December 07, 2008, 09:59:52 AM »

I have several ANLI RD-88H HT (BNC type) antennas.  The RD-88h are being used on 2m HT, dualband HT, and scanners.  Great improvement over the stock rubber duck antenna.  Instead of "you are not quite into the repeater" to "good to hear you".

The length of the antenna puts considerable strain on the BNC connector.  In a pinch I have also put one on the back of my FT-2500 and used full power.  It worked, but I do not recommend it for anything other than a quick install.

Mike
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