[Skimmertalk] Skimmer Advice (K3 IF issues)

Mon Nov 9 22:34:37 EST 2015

Bob,

Thanks for the reply and advice. Exactly what I was seeking.

A few comments...
1) RX Guard on the K3 rx-in/rx-out... The idea here was mainly to protect
the front end of the K3 "just in case" I do something dumb like disconnect
the BPFs late at night and transmit on the same band. Hope I never need it,
but it is insurance. (overkill)

2) A few years ago I'd seen that 1st presentation of yours on the web.
Thanks for providing that and making it available. In fact, I picked up
that Mini-Circuits power splitter you mention on your recommendation and
have used it.

3) My understanding was that my K3/LP-Pan setup had the 24kHz limitation in
Skimmer (using the Softrock-IF setting) and that also limited decoding to
24kHz. I guess I didn't pay attention to the spot frequencies - I had just
noticed that when I used page up or down in Skimmer, the labels disappeared
on the bubbles so I figured that it was only decoding what was on the
waterfall. Also, when recording Skimmer (with Softrock-IF), it only records
24kHz wide. Tonight I put the rig on 7056kHz and waited for spots in
Skimmer - they were all +12/-12 kHz (no spots in the low part of the band
but there was activity), so I don't think it's really decoding in this
mode.

When I view the CWSkimmer bandscope (which I like as well), I only see
24kHz of spectrum.

4) With regard to using the Pixel Loop's Key line as protection... I have
used that, but wondered with SO2R, if I needed to (or even could) connect
both rigs to it.

5) To get the waterfall (ie HDSDR), Skimmer, rig and N1MM+ to all follow
nicely, I wonder if it would work with a virtual serial port splitter tool
like LPB2.

Maybe I should sell the Afedri (which has been a good unit) for a QS1R as
you suggest. However, I see that they are out of stock.

In any case, this sounds like a "Franklin fix" is needed (Santa will need
some bills with Ben Franklin's picture on them to upgrade my shack :).

Thanks again Bob.

73, Pat
N0HR

On Mon, Nov 9, 2015 at 7:27 PM, Bob Wilson, N6TV <n6tv at arrl.net> wrote:

> It sounds like you want both a waterfall display wideband band scope *and*
> local skimmer spot decoding to happen at the same time, on multiple bands,
> using your present equipment.
>
> See my online presentation for some ideas, but it sounds like you already
> have most of it:
>
>    - Adding a Software Defined Radio (SDR) to an SO2R station
>    <http://tinyurl.com/4zama4>
>    - Using Waterfall Displays as a Contesting Advantage
>    <http://bit.ly/UsingWaterfall2015>
>
> In sum, for fixed Waterfall display, I recommend a passive (or active) RF
> splitter on K3 RX IN/OUT line, feeding any SDR and running it with HDSDR or
> WinRad as the band scope, instead of CW Skimmer.
>
> For multi-band spot decoding, use SkimmerServer on a multi-band antenna,
> such as the Pixel loop or a tribander, and a QS1R (plus telnet to an RBN
> node such as VE7CC).
>
> There's no need to use any Rx Guard between the K3 RX ANT Out and SDR
> Antenna inputs, because there is never RF output there (other than bleed
> through).  Using an Rx Guard does no harm, but it's not needed.  If you
> have bandpass filters on the main K3 TX output, there's really no way for
> high RF to get to the SDR, unless you have second transmitter on the same
> band on an very nearby antenna (which seems unlikely).
>
> Using a Pixel Loop, the loop's power control box can by keyed with your
> PTT line on the K3, and that will remove DC from the Pixel preamp every
> time you transmit (works OK at QSK speeds).  So again, with that set-up, no
> need for an RX Guard on the SDR.
>
> Re. CW Skimmer, it *does* decode all 192 kHz, but you can only *see*
> about 12 kHz on the Skimmer waterfall at a time, and you can't zoom in our
> out.  However, you can press the [PageUp] or PageDown] keys while CW
> Skimmer has to focus to see the rest of the decoded frequencies.  To
> see "blips" (no waterfall) of the *entire* spectrum being decoded, start
> CW Skimmer and select View -> Bandscope from the menu (most folks have
> never tried that option, but they should).  You can then click on any
> signal in the band scope window to retune the SDR to that frequency,
> instead of pressing PageUp and PageDown.
>
> Regarding having the cursor on the Waterfall follow your radio's tuning
> knob, it's easy to do with contest software the supports OmniRig, since
> HDSDR and WinRad also use OmniRig, but that solution will not work with
> N1MM+, because N1MM+ does not support OmniRig.
>
> I'd would recommend instead a P3 scope.  Maybe you can treat yourself to
> one this Holiday Season. ;-)  Maybe sell one of those extra SDRs to get the
> funds for one.
>
> For multi-band spot decoding SimmerServer, you need a QS1R SDR, or one of
> the other supported models.  The QS1R is the only one that can decode seven
> bands at once.  Or you could dedicate one SDR to each band.
>
> 73,
> Bob, N6TV
>
> On Mon, Nov 9, 2015 at 3:26 PM, Pat Rundall <pat at n0hr.com> wrote:
>
>> Skimmer Gurus...
>>
>> I'm looking for a bit of advice on how to improve my setup for CW
>> contests.
>> Namely, I'd like to avoid the 24khz limit of the k3/LP-Pan setup and
>> issues
>> with the output shifting frequencies when I change filter settings on the
>> k3.
>>
>>
>> The Goal:
>> Aggregate useful skimmer spots -> N1MM+ for the current and adjacent
>> bands.
>> I'd prefer to have the skimmer running on the active antenna (ie a beam
>> rather than a short vertical or loop)
>>
>>
>> The Current Setup
>>
>>    - N1MM+ on a laptop
>>    - K3/100 as the main rig w/RX2
>>    - LP-Pan2 from IF-Output of K3
>>    - USB sound card capable of 192khz
>>    - Currently, I'm routing the RX output of the k3, through a
>>    DX-Engineering RX-Guard and then into the RX input as a means of
>> protecting
>>    the front end in a SO2R environment (also using BPFs, etc.). (100w)
>>    - Aggregating spots from a local packet node with wintelnetx
>>
>> Other HW available
>>
>>    - Afedri SDR
>>    - Pixel RX loop
>>
>> The problem
>> I noticed in Sweepstakes CW that the Skimmer is only decoding +/-12khz
>> rather than the whole 192kHz at once. Also noticed that when I change
>> filter settings on the k3, the frequency jumps on Skimmer. I've read where
>> both of these issues are known and there really isn't a working solution
>> apart from simply using other hardware. Unless I've missed it, I don't see
>> a solution to these issues offered by the vendors (Elecraft/LP-Pan/VE3NEA)
>>
>> Options
>>
>>    1. Setup the Afedri SDR to be a standalone receiver by putting a
>>    splitter after the RX-Guard on the RX-out/in loop. I may see a bit of
>>    signal loss on that. I'd probably setup the Afedri on a separate PC
>> running
>>    an SDR app (HDSDR?) with Skimmer. Then when I change bands, manually
>> change
>>    that on the app. Not horribly inconvenient.
>>    2. Setup the SDR on the RX loop with another RX Guard. (Even if there
>> is
>>    a fix to the K3 IF issues, I may setup another SDR on the loop to
>> monitor
>>    the adjacent band)
>>
>> Other thoughts?
>>
>> Thanks
>>
>> Pat N0HR
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