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Re: [TowerTalk] Portable Analyzer

To: "Riki, K7NJ" <k7nj@awinets.com>, towertalk@contesting.com
Subject: Re: [TowerTalk] Portable Analyzer
From: "Richard (Rick) Karlquist" <richard@karlquist.com>
Date: Sun, 10 Jul 2016 11:03:57 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 7/9/2016 10:08 AM, Riki, K7NJ wrote:

sticker indicated that it was manufactured in 2016. Any suggestions for a
good portable analyzer that works well in a high RF environment would be
appreciated.

73 - Riki, K7NJ


The news isn't good.  I have an AIM-4170 and an SDR-kits VNWA.
They work fine in a lab environment.
Unfortunately, they operate at low excitation levels using small signal
Gilbert cell mixers that limit their ability to handle
large signals.  BCB reject filters may help, but are not a panacea.
(There are some high dynamic range Gilbert cell mixers
available, but they chose not to use them).
The pocket size battery operated meters are unlikely to be
any better, due to the constraints of designing within that
configuration.  Ask the manufacturers how much RF goes to the
antenna and use that as a crude figure of merit.

The manufacturer of the AIM-4170 also offers a "professional"
model that claims to be able to handle high ambient RF levels.
It is only "portable" if you don't mind bringing along a laptop.
I haven't been able to justify spending the money on this
for my limited needs.

Another thing I have is an N8LP vector wattmeter.  This tells
me the complex impedance of the antenna no matter how much
QRM there is, because I excite it with my rig set on 5 watts.
It is kind of portable, using a gel cell and an IC-706 to
go along with it.  If you measure the antenna through a
feedline of any significant length, you have to correct the
reading yourself with Smith chart software.

Rick N6RK
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