[ICOM] RE: Good aftermarket HT antennas

[John Geiger]

Thanks Aaron,

This is exactly the kind of info I am looking for.

73s John NE0P


----- Original Message ----- 
From: "Hsu, Aaron (NBC Universal)" <aaron.hsu at nbcuni.com>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Friday, April 14, 2006 8:52 PM
Subject: [ICOM] RE: Good aftermarket HT antennas


I have several "thin" whip antennas - a SMA503, the MFJ equivalent, one
with a 17" whip (forgot the manufacturer), and several BNC antennas.
They're all basically the same with two common threads:

1.  Some use a tuned circuit (L/C) to better match the HAM bands  These
antennas present a low SWR for 2M/440, but reduce sensitivity for all
other bands.  The better the matching on the HAM bands (higher Q), the
better the antenna "seems" to perform on those bands, but the worse it
gets outside the HAM bands.

2.  Some are just a piece of wire soldered to a suitable antenna
coupler.  Possibly trimmed in size to better match a particular HAM
band, but, otherwise, nothing special.  These antennas give you WIDE
receive coverage, but aren't matched to the HAM bands thus producing
higher SWR and reducing effectiveness.  Works great if you want a
general purpose antenna for that receiving out-of-band, but not optimum
for 2M/440 work.

The SMA503 has a matching network, so I can't receive the broadcast AM
band on my VX-1R.  How "bad" is it in this respect?  I put a piece of
0.5mm mechanical pencil lead in it's place and was able to pickup all
the local AM stations.  However, it works great on 2M and 440.  The MFJ
equivalent thin whip was able to cover the AM brodcast band all the way
up to the limits of the VX-1R, but the SWR matching on 2M/440 was pretty
bad (3:1 or worse).

In my experience, the best dual-band (2M/440) antenna I've used is the
Larson KD4-270.  Rugged and matched well, but not available in SMA.
Next is the Icom antenna that came with the W2A (also BNC).  The SMA503
works for me on the VX-1R and I keep the MFJ thin whip on my Icom IC-R2
receiver (where it works well).  Strangely enough, the antenna that came
with the IC-R2 is a dual-band 2M/440 short duck - not quite optimal as a
scanner antenna!

Honestly, most HT antennas of the same size perform pretty much the same
- it comes down to how well matched they are to the band(s) of interest.
Choose a well matched antenna, lose wide-band coverage...and vice-versa.
And the "miracle" short ducks are nothing more than a 50-ohm dummy load.
Strange how they're almost the exact same size and shape of a 50-ohm
terminator, eh?  OK, a dummy load with a short radiating whip <g>.


73,

  - Aaron Hsu, NN6O (ex-KD6DAE)
    {nn6o}@arrl.net
    {aaron.hsu}@nbcuni.com
    No-QRO Int'l #1,000,006
    . -..- - .-. .-   ".... . .- ...- -.--"
 

-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
On Behalf Of John Geiger (NE0P)
Sent: Friday, April 14, 2006 11:19 AM
To: icom at mailman.qth.net; icom-t81a at yahoogroups.com; t8a at yahoogroups.com
Subject: [ICOM] Good aftermarket HT antennas


Does anyone on the list have a recommendation for a good aftermarket HT
antenna to use.  I have an Icom T81A and am looking for a good
performing 2/440 antenna for it.  I am not interested in anything longer
than 10 inches or so due to practical considerations. I am looking for 1
antenna around 5-8 inches for regular use, and a second "mini antenna"
around 1-2 inches for close in work, which I need to minimize the size
of the HT and antenna package.  Here are some antennas I am looking at:

Full sized
Comet SMA503, SMA3, SMA703 (with 1.2G)
Diamond SHR519
Maldol MH-511 with 6 meters
MFJ 1713S, 1716S
Pryme RD9SMA

Mini antennas
Comet SMA501
Diamond SRH805 with 1.2g
Maldol AS-25
Pryme RD2SMA
MFJ 1719S

Any suggestions?

73s John NE0P
 

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