[Skimmertalk] Antennas for Skimmer radios?

Jeff Maass jmaass at k8nd.com
Fri Dec 23 20:47:45 PST 2011

The purpose of the RBN is to identify what stations are on-the-air, on what
frequency, and where propagation has allowed them to be heard. The strength
at a specific location is irrelevant to the operator of that Skimmer: the
station may be much stronger or much weaker elsewhere. 

For a Skimmer used exclusively for on-site consumption by a single station,
then yes, you might want to have the receive ability tweaked to match the
ability to receive by the station that will be making the QSO. However, I'd
much rather know that a station is on a frequency and not be able to work it
than to not be notified what is on the frequency. I can quickly judge the
workability when I go to the frequency or by the signal to noise measure,
and QSB will change that in the time between Skimmer 10-minute updates.

At PJ2T, the normal use for the individual on-site CW Skimmers (not the PJ2T
Skimmer Server) is to provide spots on the lowbands - 160m and 80m, and
sometimes 40m. To do this, we put the SDR-IQ receivers on the switched
receiving antenna system, where they can each be switched to any of the
Beverages (1000-foot Europe, 650-foot USA/JA), Flags, or RX 4-square
antennas for receiving. On those bands, if we can hear it we can work it.

But we've also used Skimmers on the higher bands, to watch for the first
signs of an opening. Before this year, we used one CW Skimmer to keep an eye
on 10-meters for the first signs-of-life so we don't waste any time in an
opening. For that, we'd put the Skimmer receiver on a monobander pointed at
Europe and/or USA: we wanted the best antenna possible to be used. 

Every owner of a CW Skimmer or Skimmer Server operation picks what antennas
are needed to meet their own goals, and that might change as needs change.

73,  Jeff  K8ND

> -----Original Message-----
> From: skimmertalk-bounces at contesting.com [mailto:skimmertalk-
> bounces at contesting.com] On Behalf Of Andrew O'Brien
> Sent: Friday, December 23, 2011 9:28 PM
> To: skimmertalk at contesting.com
> Subject: Re: [Skimmertalk] Antennas for Skimmer radios?
>  I guess this brings up the question about the purpose of the skimmer
> antenna.  It seems to me that an active antenna such as the ones
> mentioned in this thread , receive better than the antenna to be used
>  when transmitting.  I always assumed that a station's receiving
>  skimmer antenna should be generally reciprocal to the performance of
>  the transmitting antenna.  This based on the the theory ...if you hear
>  'em, you can work 'em.  Super skimmer antennas churning out "spots"
>  for the world maybe useful , but is that what we want from skims ?
>  Andy K3UK
> >
> > On Tue, Dec 20, 2011 at 3:31 PM, John Reilly <reillyjf at comcast.net>
> wrote:
> >> I'm using a Pixel Magnetic Loop (RF Pro-1B) mounted at 10 ft; however,
> >> it is surrounded by 25 ft houses!  I'm planning to move my loop up to
> 25
> >> ft plus next Spring to see if getting it at or above the houses will
> >> improve performance.  I also have a Clifton Labs vertical, but it
> >> doesn't seem to perform as well as the mag loop.
> >>
> >> I also studied the N6TV stats and asked K3LR what they were using --
> >> vertical(s) (I assume they are active). I use a QS1R.
> >>   - 73, John, N0TA
> >>
> >>
> >> On 12/20/2011 12:09 PM, H Lawrence Serra wrote:
> >>> Pete N4ZR suggested I put this out to the group:
> >>>
> >>> I would like to hear from skimmer ops on what ANT systems they are
> using for
> >>> their skimmers.
> >>>
> >>> I am in the SW corner of the US, on the wrong (west) side of close-by
> Mt.
> >>> Soledad and have roof space-limited ANTs. I use a PA0RDT active mini-
> whip ANT
> >>> about 5 ft above my roof for my SDR-IQ radio which feeds the skimmer.
> I was
> >>> surprised to see from N6TV's RBN stats that I have the lowest SNR
> average for
> >>> signals of reported RBN skimmers, and post only 1/5 the spots N6TV
> had and 1/10
> >>> the spots WA7LNW had from my part of the country.
> >>>
> >>> I have tried putting my 2-el Steppir yagi pointed 045T on the skimmer
> when I am
> >>> not contesting, and even that little extra gain results in more
> skimmer spots
> >>> from NA and EU. My plan now is to find a used A3 tri-bander that I
> can cut down
> >>> to a 2-el due to space limitations and because I want a broad beam
> width. I plan
> >>> to use a coupler to feed both the active mini-whip and the 2-el yagi
> to the
> >>> skimmer's feedline, so I don't have to mechanically switch ANTs when
> SkimScan
> >>> switches to the low bands at night.
> >>>
> >>> Anyway, I would be interested in what SDR or other radio you use, and
> what
> >>> ANT(s) you use for your skimmers.
> >>>
> >>> 73, Larry N6NC
> >>> _______________________________________________
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> >>>
> >>>
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