[amsat-bb] Advice for a portable ground station

R.T.Liddy k8bl at ameritech.net
Fri Jan 16 16:47:27 UTC 2015


Tom,

Glad to see someone joining us portable & Grid Expeditioner
folks. It's a blast!

My advice after several years of Gridding from 60+ locations
across US & Canada is to start out simple. Put together something
that works easily and successfully to begin with and make improvements
one-at-a-time from there. Having too many complicated things when
just starting out can be very frustrating.

You can see my setup on my QRZ.com page. It is very simple.
- Dual-band XCVR (no need for duplexer)
- Arrow antenna (Tripod added since pic was taken)
- 10 ft runs of RG8X (tie-wrapped together)
- No preamps, no chokes

With this setup I work stations right down to LOS.

Good Luck and never hesitate to ask this group whatever question
comes to mind - people here will fall over themselves to offer great
advice at all times!

73/GL,      Bob K8BL/5  (Lumberton, TX) 


________________________________
 From: "tom.wz9u at gmail.com" <tom.wz9u at gmail.com>
To: "amsat-bb at amsat.org" <amsat-bb at amsat.org> 
Sent: Friday, January 16, 2015 2:06 AM
Subject: [amsat-bb] Advice for a portable ground station
 

The lack of a fully searchable archive for this list has made this post necessary, my apologies for a noob-style query.


I’m gradually assembling a portable ground station for the FM satellites, primarily using John Heath’s (G7HIA) article “Down-to-Earth Satellite Communications” (PDF), focusing on his “Awesome” configuration:


Dual-band HT


Diplexer


2m amplifier


70cm preamplifier


Arrow II antenna



In that article he uses RG58 coax, perhaps 15-20 feet max.  Is there a better choice that also works in that application?  Considering the lengths involved, price per foot is not really an issue.


He also calls out an RF choke at the feed point of the 70cm antenna, but gives no detail about its material or construction.  It looks to me like a few turns of RG58 on some type of ferrite core.  I’ve spent hours Googling for information (commercial or DIY) and have come up mostly empty-handed.  All the “meaty” stuff is for HF only.


A final question concerns the various connectors involved.  The illustrations in that article aren’t the best, but it seems that he’s using BNC terminators on all the cables, and BNC-to-UHF adapters where required.  I’m concerned (perhaps too much) about cumulative losses, both from the coax and all those adapters.


My goal is a tripod-mounted antenna, operating on battery power from various parks and forest preserves nearby.


Can anyone clarify my understanding here?


Tom WZ9U




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