[Elecraft] K3 Sub-receiver use

Wed May 26 12:21:15 EDT 2010

On Tue, 2010-05-25 at 22:36 -0700, Brett Howard wrote:
> Can the P3 at least show where the sub RX is and its BW and what not if
> its on the same screen full of where the Main RX is?

Yes, that's the way it works normally.  Even though P3 is receiving the
main receiver's IF output, there is a cursor on the screen to show where
the sub receiver is tuned, assuming it is within the currently-displayed
span.

Alan N1AL

> 
> ~Brett
> 
> On Tue, 2010-05-25 at 21:25 -0700, Alan Bloom wrote:
> > 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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