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Re: Topband: HMC580 instead of W7IUV preamp

To: Mike Waters <mikewate@gmail.com>, topband <topband@contesting.com>
Subject: Re: Topband: HMC580 instead of W7IUV preamp
From: "Richard (Rick) Karlquist" <richard@karlquist.com>
Date: Tue, 8 Sep 2015 22:24:57 -0700
List-post: <topband@contesting.com">mailto:topband@contesting.com>


On 9/8/2015 7:02 PM, Mike Waters wrote:
Given the recent discussion about the need for low-noise preamps for the
Waller Flag, it would be interesting to learn what the NF on 160 for
this device might be.

It's rated for "DC" up into the GHz range. However, as N4IS pointed out,
a good NF at VHF does not mean a good or better NF below 2 MHz.

73, Mike
www.w0btu.com <http://www.w0btu.com>


I've characterized this device and can tell you that the 1/f
corner is well below 2 MHz, because it is based on HBT
technology.  The devices that are good at VHF and noisy
at 2 MHz use MOSFET, GaAsFET, or ephemt technology.
JFET devices are also low noise at 2 MHz if they have a sufficiently
low channel resistance.

Rick N6RK
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