NF4AC EOC Alachua County

NF4AC (Alachua County EOC Backup Ham Station)

Radio station of the North Florida Amateur Radio Club

Page updated: Dec 29 2022

Archival
Information

Official License - 2018

OFFICIAL MINUTES

Dec 2022 Antenna Work Day -- All HF Antennas Up and Working!

Center Balun

(This photo is the extreme WEST end of the wire, which was threaded, treetop-to-treetop- for >150 feet at great height with a series of launched lines back in 2021.)

Rough SWR Curves For Each Antenna - 12/28/2022

Jan 2021 Antenna Work Day Report --
Big improvements!

John Trites NO5X Feb 2020 Report

Jan 2020 Chigger Antenna Improvement

Oak Tree Antenna Test Results June 29

COMPARISON: Measurements Made At Santa Fe College 6/25/2019

June 1 Antenna Improvement Documentation

TABLE TWO
TimeLine Reports on EOC HF Antennas
Reverse Chronological Order
(most recent first)

Date / Summmary	Link to Report
Dec 2022 Rough SWR Curves after antenna maintenance	Antenna SWR Curves 12/22/2022
Jan 2021 Antenna Work Day Report	Jan 2021 Work Day Report
Feb 2020 - John Trites Measurements & Stub Solutions to ham bands	Trites Feb 2020
Jan 2020 MFJ SWR measurement	Jan 2020 MFJ SWR Plot
June 1 -- Measurements made after tower supporting rope raised significantly higher	June 1 2019 Report
May 18 - interference rapidly declines with distance from EOC; possible 2nd antenna (spectrum analyzer calibrated measurements)	May18th Report
May 14 - Coax= good; Noise environment = the problem; antenna impedances = way way low (roof interaction) (spectrum analyzer calibrated measurements)	May 14th Report
April -- initial spectrum analyzer spectral comparisons between noise signals at EOC versus residential home	See Table One below
March 23 - Comm tests across Gainesville largely failed from EOC without repeaters; HF antenna SWRs confirmed poor	Mar23 Investigations
Feb 22 - Confirmation of Noise measurements using receiver S-meter	Noise Measurements Feb 22
Nov 28 2018 -- Initial confirmation of noise issue, using receiver S-meter	Nov28 Confirmation
Sept 2018 - Initial evaluation of newly installed antenna	Antenna Initial Eval
May 2018 - Consensus Antenna Design	Consensus Antenna

Typical residential BuckMaster SWR Curves measured 2019 NW Gainesville

To make a quck comparison between the EOC results the Gibby household, this table presents the spectrums to compare:

Table One
INITIAL SPECTRUM ANALYZER COMPARISONS BETWEEN RESIDENTIAL AND EOC NOISE ENVIRONMENT

	Gibby Houshold	EOC
Antenna Signals 3MHz - 8 MHz Afternoon	Gibby Receiving Signals (many radio signals obvioius)	View the top, blue line here: EOC Receiving Signals (virtually no signals obvious and lots of broadband noise)
Building Internal electromagnetic RF fields (undesirable)	Nearly non-existent Gibby internal home fields: Gibby internal signals	significant electromagnetic fields inside EOC (1000 times stronger than at Gibby household) EOC fields internal

Gibby E-Field Signals Baselines April 23

2-foot dipole wand; 3 kHz RBW; 0 att internal; preamp ON; 6db external attenuator; 3.5-4MHz; yellow trace is internal noise; purple is signal with all ham transmitters OFF

GibbyE-FieldBaseline04232019

EOC E-Field Signals April 23
EOC E-Field Radio Room Floor 04232019