[Elecraft] KX3-2M module?

[Edward R Cole]

Stewart,

That's a good question.  Certainly lower RF output will generate less 
heat.  One issue that would need to be determined is whether the 2M 
module has any operating mode which would result in a full output 
spike which would likely destroy 0 dBm input circuit 
components.  This has been documented for many non-Elecraft radios.

But let's assume you can turn power to 0.1w at minimum (that is 
currently indicated on the KX3 PWR control).  That would be 100mw or 
+20 dBm level.  That can be attenuated to 0 dBm using a chip 50-ohm 
load or 20-dB attenuator (which I would be sure was rated for 3w - 
just in case).  Design of transverter IF connections could either be 
common Rx/Tx or separate (preferred).  If common, the transverter 
will have some sort of IF T/R control so load/atten. could be 
inserted on the Tx side.  Inserting 20-dB attenuation on receive 
would affect receive sensitivity and possibly system NF.  The circuit 
using a 50-ohm load would couple low power via a 10pF capacitor.  You 
might need to have an adjustable drive level pot following this (make 
it an L-pad).

With operation at this level frequency drift characteristics will 
likely by the same for Rx and Tx.  I can test this concept when I get 
the 2M module for testing on my bench.

73, Ed - KL7UW

------------------
Date: Wed, 9 Apr 2014 08:24:57 +0100
From: "Stewart at g3ysx.org.uk" <stewart at g3ysx.org.uk>
To: Dave <dave at g0dja.co.uk>
Cc: "<elecraft at mailman.qth.net>" <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] KX3-2M module?
Message-ID: <967726D0-0801-494F-9816-88C484D223BC at g3ysx.org.uk>
Content-Type: text/plain;       charset=us-ascii

When driving a transverter presumably you will be running at 0dbm 
rather than at 5W. I wonder if the KX3 still experience thermal drift 
due to PA heating at very low power?

Stewart/G3YSX
Sent from my iPad


73, Ed - KL7UW
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