[Elecraft] K3 Sub-receiver use

Wed May 26 02:47:40 EDT 2010

Hi Alan,

No more a "dream" for me !
If i dare, you can put me on the list!

73 QRO,
Rudolf, HB9ARI

PS Excuse me  for my bad mood !
I "love" too much MY K3...

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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>   