[Elecraft] K3 Sub-receiver use

[Alan Bloom]

Hi Rudolf,

At the bottom of this message I will copy a posting from W3SZ on the
LP-PAN email list that describes how he added IF output to his K3
sub-receiver.  He used the Z10000 buffer amp from Clifton Labs:
http://www.cliftonlaboratories.com/z10000_buffer_amp.htm

If you don't mind modifying your K3, it looks like that should allow you
to use the sub-receiver with a P3.  When I get time I'll have to try it
on my K3 and see how it works.

Alan N1AL



On Tue, 2010-05-25 at 22:01 +0200, hb9ari wrote:
> Hi Rich,
> 
> Very bad news !
> 
> That was my 1st idea when ordering the P3
> to use it for "wide" span use for phone mode.
> (50Mhz in priority during possible "apertures")
> For digi mode, as JT65, the ~2kHz width
> of "waterfall" is 100% sufficient, because
> frequencies are well defined (for ex 14.076Mhz)
> I'm quite sure now that it was a bad idea to have ordered
> a P3 but, with your accurate explanation, i will
> renounce to the sub-receiver ordering (and
> roofing filters)!
> 
> I regret that a P3 connection to the sub-rcvr
> is not possible, and, as i'm not an RF engineer,
> i don't understand the reason(s)!
> 
> At my point of vue, it's not 100% correct to say that
> the KRX3 is like a 2nd receiver !
> 
> Just in time to stop for the KRX3 ordering but for the P3...
> may be eBay ?
> 
> My best 73,
> Rudolf, HB9ARI

============================================================

-------- Forwarded Message --------
From: w3sz <w... at comcast.net>
Reply-to: lp-... at yahoogroups.com
To: lp-... at yahoogroups.com
Cc: w... at comcast.net
Subject: [LP-PAN] KRX3 IF tap up and running
Date: Fri, 02 Jan 2009 00:56:35 -0500

Hi Larry,

I didn't get a chance to hook up the LP-Pans yet [because the audio  
cables I need are up at my hilltop QTH], but I did install the KRX3  
and its Z10000 buffer amp, and both the main K3 IF output and the KRX3  
subreceiver IF output seem to be working fine.  I ran the main IF to  
the main receiver on my Flex5000 and the KRX3 subIF to the subreceiver  
on the Flex5000.

Everything seems to be OK in terms of how I chose to get the IF from the KRX3.

I am working a long day tomorrow as well as Saturday AM, but I am  
hoping to get a chance to run up to the hilltop and pick up the audio  
cables and then get the LP Pans hooked up Saturday afternoon.

This is a brief summary of what I did with the KRX3:

I used the Z10000 as buffer amp inside the KRX3.

I got +12V from a 12SA pad near to P86A.
Power and RF connections to the Z10000 were done from the underside of  
the Z10000.

I took IF output from KRX3 from P86A and used RG174U to take this to  
input of Z10000.

I mounted Z10000 on an unused FL position using a 1/2 inch standoff.

I mounted a dual female SMA connector in the REF hole at the bottom  
corner of the K3 just below the official IF out BNC.  I then used a  
right angle premade small surplus coaxial cable to take the signal to  
the KRX3 and thus the Z10000.

I entered the KRX3 at the back left corner opposite to J92, because  
there was already an opening there.

I ran the coax inside the KRX3 bottom shell, beneath the main KRX3  
PCB.  I brought it up to the Z10000 by running it through an unused  
hole meant for an FL standoff.

At first check, using the two subreceivers on the Flex5000 to receive  
the IF signals from the K3, the main K3 and the KRX3 subreceiver IF  
outputs seem to be equivalent.

When constructing the Z10000, I used the -U [Universal] options, not  
the K2 options.  I chose to set it up for zero gain, and thus chose  
R907 to be 499 ohms, and R905 to be 4.7K, as per section 2.3.3 of the  
Z10000 manual.

I attached a jpg file with the two IFs from the K3 going to the Flex  
5000.  The K3 main IF goes to the main Flex receiver and the DRX3 sub  
IF goes to the Flex sub receiver.  The signal is Radio Moscow on 40  
meters.

73,

Roger Rehr
W3SZ
http://www.nitehawk.com/w3sz