[Elecraft] Sub Receiver I.F. Tap

[Edward R Cole]

Jack,

If by "mistune" you mean that the impedance will be loaded down, yes 
that is likely.  A buffer amp following will solve that .  My reply 
was merely to indicate tapping the 1st IF at W3 is a good 
decision.  I run both main Rx IF and sub Rx IF to LP-Pan that have 
the optional IF amps installed (now std in the LP-Pan 2).  Both 
appear to work fine bringing out the 1st IF to my LP-Pan which in 
turn provide IQ baseband input to a four port soundcard for diversity 
reception on 2m-eme (a special application using digital modes).

I did determine that feeding the 1st IF to the 2nd IF of the K3 
loaded the panoramic display at frequency zero, so I select a xtal 
location that is unfilled to effectively disconnect the 2nd IF.  But 
normal use of the K3 using the entire receivers works fine.  I do not 
detect any loading of the 1st IF by either LP-Pan.

Now probably one should use a 0.01uF cap instead of 0.001uF for 8.215 
MHz.  That will provide a little more RF coupling.

One other item I did omit is the use of a ferrite on the RG-174 for 
isolating the shield for any noise introduction to the IF.

73, Ed - KL7UW


From: wa9fvp <repair at willcoele.com>
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Sub Receiver I.F. Tap
Message-ID: <1492360444817-7629368.post at n2.nabble.com>
Content-Type: text/plain; charset=us-ascii

  Edward R Cole  wrote ;

I brought out the 1st IF of the sub receiver from that point using
0.001 uF disc ceramic coupling cap to RG-174 coax snaked out thru a
hole in the sub-Rx shield to a BNC on  back panel of the K3.

-------------

I think that connecting the coax via a capacitor would load and mistune the
I.F..  That's why the main receiver was designed with a buffer JFET.

-----
Jack WA9FVP


73, Ed - KL7UW
   http://www.kl7uw.com
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