[Elecraft] KX3-2M extended receive?

[Edward R. Cole]

I know where Steve is coming from with his reply, though you would 
need to "step back in time a few decades".  In the 1970's I was an 
inveterate backpacker, going nearly every weekend into the Sierra's 
where you park your car at 9,000 feet altitude and climb from there 
often over 12,000 foot passes.  My typical backpack included 4-season 
"expedition" sleeping bag and similar level 2-person tent.  This 
required an extension rack on the backpack which typ weighed 
60-lbs.  My weekend treks were typically 16-20 miles and this is not 
level walking, but often onto snow covered passes (in July).  The 
ultimate "hike was when I took the "Wonderland Trail" that 
circum-navigates a 113-mi trail circling Mt. Rainier.  My hiking 
partner and I preshipped two re-supply caches to accomplish this.  We 
crossed two glaciers on that trek.

A good friend of mine, KL3BD, made three ascents of Mt. McKinely 
(near 21,000 feet) carrying a 2m-HT.  I talked to him a couple times 
on his climb.  I can envision a KX3 going on such a trip some day.

The point Steve is making is every extra ounce of weight is something 
that you must carry on your back.  You want most of it to be "fuel" 
(i.e. food and not ballast).  Taking two radios, each with a battery, 
is excessive on such trips.  I can't even comprehend taking a 15-lb radio!

OK that being said, let me address the technical issue.  The KX3 is a 
direct conversion SDR that tunes to 54-MHz.  There may be a technical 
upper limit on what this SDR can cover in frequency.  Note the 
144-148 is added via a transverter (meaning it is hetrodyned down to 
50-54).  I would suspect to cover 162.55 MHz would require a separate 
Rx converter, so it may be easier to consider a separate radio for 
that.  Asking for the 2m transverter to include the wx band would 
probably involve major redesign:  two-freq LO plus RF circuitry that 
would be tuned to 162-163 MHz.

There becomes a technical/physical limit to what can be added in 
functionality in one radio.  Providing wideband circuits to provide 
decent Rx sensitivity over 144-163 MHz is problematic to obtaining 
good performance on the primary objective of the 2m band.  An example 
is my K3 which tunes 28-32 MHz for receiving 144-148 but does not 
transmit well above 146-MHz.  Elecraft solved that for its own line 
of transverters by providing two LO freqs. to use 28-30 MHz.  The 
fact they decided to use the 6m band as IF for 2m on the KX3 is proof 
they are thinking how to improve.  Seriously, I would be surprised if 
the wx-band can be added (though I understand the wish for that).

73, Ed - KL7UW
PS:  Hiking now consist of hauling luggage thru airport terminals!
------------------------------

Message: 47
Date: Sun, 8 Jan 2012 07:32:45 -0800 (PST)
From: Steve KC8QVO <kc8qvo at yahoo.com>
Subject: Re: [Elecraft] KX3-2M extended receive?
To: elecraft at mailman.qth.net
Message-ID: <1326036765596-7164932.post at n2.nabble.com>
Content-Type: text/plain; charset=us-ascii

Though I respect your opinion, Mike, and everyone else that shares the same
sentiment, I must entirely disagree with your point about using an HT to
supplement the KX3 vs. the multi-mode capability on 2m.

My basis for my comments is backpacking. I ask those that are consider the
multi-mode operability of the KX3 as being the sole reason wideband receive
is not feasible and that an HT must be required to supplement that which the
KX3 does not cover if you have ever gone backpacking. That doesn't mean a
short day hike or walking a mile to a camp site for the weekend, I am
talking about packing everything you need for 2 or more days covering 20+
miles.
========snipped the remainder for brevity.


73, Ed - KL7UW, WD2XSH/45
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