[Elecraft] K3 Sub-receiver use

Wed May 26 00:25:15 EDT 2010

Yes, the P3 assumes it is connected to the main receiver's IF output, so
if it is actually connected to the sub-RX it would still work but would
not display the correct frequencies and levels.  If this becomes popular
enough maybe we should think about adding sub-RX support to P3 firmware.

Alan N1AL

On Tue, 2010-05-25 at 23:50 -0400, Guy Olinger K2AV wrote:
> Wouldn't there be a K3 interoperating with P3 firmware issue with
> running the P3 on the sub-RX?  Just because you could feed a
> **stand-alone** box with a non-company mod for sub-RX IF, does not
> mean the P3 would change the sub-RX with a click on the P3. There is a
> lot of proprietary communication between the K3 and the P3 over the
> serial connection.
> 
> Wouldn't a sub-RX feed to a P3 need to be specifically supported by
> Elecraft firmware, both in K3 and P3?  Last remarks from them in this
> thread were negative, particularly about isolation at a switch.
> 
> That aside, I believe someone using the sub-RX with the TX in split,
> while leaving the main RX to feed the P3, would accomplish the same
> end.  This WOULD be a problem on other rigs where the second RX is an
> inferior RX, or not available.  In the K3 the sub-RX is a fully equal
> clone of the main RX, making various A/B flippity-do tricks possible
> without sacrificing performance in any way.
> 
> 73, Guy.
> 
> On Tue, May 25, 2010 at 9:48 PM, Alan Bloom <alan at elecraft.com> wrote:
> > 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
> >
> >
> >
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