[Skimmertalk] Antennas for multi-band Skimmer installations [more]

Pete Smith n4zr at contesting.com
Sat Jul 4 03:07:28 PDT 2009

More on this - I asked Jack Smith, K8ZOA of Clifton Labs about the 
difference in sensitivity between his active antenna with an 8-foot 
whip and a resonant vertical.  He says that it is within a half a dB 
or so.  The short whip is much more sensitive to noise pickup by the 
shield of the feedline, so an excellent common mode choke is 
critical.  In this connection I've been doing some experiments here 
with various common mode chokes.  I'm not done yet, but the results 
so far are kind of interesting see 

73, Pete N4ZR

At 04:22 PM 7/2/2009, Wes Cosand wrote:
>This morning I read Pete's article in the July/August NCJ, "CW Skimmer --
>One Year Later".  This week I have been following the positive comments on
>the QS1R reflector about alpha testing of Alex's multi band Skimmer Server
>software.  From his article it is obvious that Pete believes multi-band
>Skimmer installations will become more numerous among contestors and Alex's
>newest efforts appear to make the computational aspect of that simpler.
>But what do we use for antennas?  If these SDRs require an impedance close
>to 50 ohms for reasonable sensitivity, how do we do that for six or seven
>bands without a lot of complexity?  I understand that both N4ZR and K4TD are
>using active antennas from a couple different suppliers.  From the Clifton
>Laboratories website it looks like Jack is putting a lot of work into active
>antenna development.  Is this the way to go?  Will we be able to get the
>same SNR as resonant antennas like a multiband vertical?
>I am having great fun with a 40/80 fan dipole a few hundred feet from my TX
>antennas and the multiband SoftRock.  But Alex's work has me considering a
>more capable system.
>Forgive the naivete of some of my questions.
>Wes, WZ7I
>Skimmertalk mailing list
>Skimmertalk at contesting.com

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