[Icom] RE: Dual-Band HH antennas

[Hsu, Aaron]

Most ham HT's sold in the past decade or so have *really* hot receivers - we all want to be able to hear John Doe from 100 miles away with the smallest possible antenna, don't we? <g>.  To do this with the stock antenna, the manufacturer needs to put high-gain pre-amps (or high gain IF amps) on the receiver to make up for the stock antenna's -dB performance.  Unfortunately, we also want to be able to put this package in our shirt pocket (or better yet, the coin pocket of my 501's), so the manufacturers also had to cut back on the front-end filtering...there just isn't enough space in these tiny radios to put in good 8 to 12-pole crystal lattice filters.  So, instead, they use inexpensive (and tiny) 2 or 4 pole ceramic filters.

So what does this add up to?  Lots of RF hitting cheap filters resulting in lots of crap being amplified through the HT's high-gain IF chain (resulting in lots of crap comming out of the radio).  Add a "high gain" antenna to this and the HT has even more crap to deal with.

On my W32A, I use a Larsen KD270 duck.  Works well, a bit better than the stock Icom antenna, and doesn't overload the radio too much.  If I hook up the W32A to the 4.5dB gain base antenna at home or the Comet B-20 antenna I use to use mobile, forget it...crap city (expecialy here in greater Los Angeles!).

If you want to use a high-gain antenna, buy a big, bullet-proof commercial HT which has lower gain front-ends (and also have LOTS of filtering).  For the average HAM HT, stick with the duck.

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

-----Original Message-----
From: Dan R [mailto:w0nbx@rushmore.com]
Sent: Friday, September 13, 2002 2:11 PM
To: icom@mailman.qth.net
Subject: Re: [Icom] Dual-Band HH antennas


Not on a W32A. At least not in my experience. There is something about that
radio that want's the STOCK antenna. Wish I knew what it was. I have tried a
number of  longer antennas on mine and the intermod goes way up and the
sensitivity seems to go down. These are comments regarding "perceived
receive issues.
73
Dan R W0NBX