VHF Digital Operations at KG4FZR MCARC Club Shack

The McMinn County Amateur Radio Club, Inc., through it's KG4FZR Club Shack located at Athens City Hall, has a full VHF digital station in operation 24/7.

The station operates on the following frequencies in the following modes:

144.390 simplex / APRS

KG4FZR-7 operates on 144.390 simplex as a full service APRS Widen-N, TNn-N digipeater and local Igate.

The digipeater responds to WIDEn-N. No where in this area does an APRS station of any kind need to have a path greater than WIDE3-3. Suggested paths for base stations are WIDE2-2. Suggested paths for mobiles are WIDE1-1,WIDE2-2 or less.

It also responds to TNn-N, or commonly called "SSn-N" where "SS" is the 2 letter state abbreviation and the "n" is a number, and responds to stations using TNn-N up to TN7-7. This effectively keeps APRS paths within the state of Tennessee. Not all digi's respond to this.

KG4FZR-7 is also a two way APRS Internet Gateway, or "Igate". It "gates" all traffic it hears to the Internet, unless the station's path includes "RFONLY" or "NOGATE" in it. Stations with those parameters in their paths are not gated.

It also gates messages for "local" stations that are nearby to KG4FZR-7 from the Internet to the RF side of APRS. The stations considered local are stations that have been heard by KG4FZR-7 directly, and not through a digipeater. KG4FZR-7 gates this type of traffic with an "RFONLY" path, i.e. the traffic DOES NOT go through any digipeater. This is similar in fashion to a "remote base" operation.

KG4FZR-7 Igate is also setup to gate "local" Internet only APRS stations beacons, messages, and objects from the Internet to RF
with an "RFONLY" path, i.e. the traffic DOES NOT go through any digipeater. "Local" stations are those that are in the McMinn County Tennessee area, and are not being gated by any other Igate, to our knowledge.

KG4FZR-7 Igate also gates weather objects and messages that originate from the Morristown, TN National Weather Service office, and the Storms Prediction Center. This traffic is gated to RF the same as the above traffic, so that stations participating in SKYWARN have a added measure of receiving this data, and seeing it visually on their stations map.

If you are in the McMinn County area and are setting up an Internet only APRS station, and would like to be added to the KG4FZR-7 APRS Digi / Igate, send an email to kg4fzr@yahoo.com and tell us your setup, call sign, name, location, and phone number. We will look at the situation, and if you meet the criteria for gating, we will add you to the allowed list in the Igate. The criteria we use is based on data provided by APRS server sys ops and software authors, and suggestions widely known across the US for such practices. If your station is added to the KG4FZR-7 Igate, your station will appear to local stations with one RF hop from KG4FZR-7, but will not go through any digipeaters. This is standard practice for Igates.

The APRS system runs on one radio tuned to 144.390 simplex, a TNC-X KISS mode TNC, and a computer running Windows XPSP2 and UI-View32 for APRS.

Please view our other APRS resources at http://www.mcminnarc.com and click on "APRS".

145.550 simplex Packet Radio

The club shack operates on 145.550 simplex in Packet radio mode at 1200 baud.

KG4FZR-1 is a local packet mailbox. It DOES NOT allow you to send messages to anyone other than those who log in to KG4FZR-1 to retrive their mail. Stations in the area who use packet, but do not have a personal mailbox may feel free to use the KG4FZR-1 mailbox.


KG4FZR-10 is a full featured Winlink (WL2K) RMS Packet Server. It allows you to send a message to any address registered on WL2K, be it ham, MARS, or tactical, and also to internet email addresses.

MCARC is the "alias" of the packet digipeater at the station.

KG4FZR-7 is the call of the local packet node.

All four of the above functions are done with one radio on 145.550, a Kantronics KPC3, and a computer running Windows XPSP2 and the Winlink RMS software.

All the packet functions and APRS functions use the same computer. The computer "boots on LAN" after power failures, and reboots automatically every day to clear the memory. There is a standby generator at Athens City Hall, and it feeds the club shack. Other that equipment failure, the only time the systems should be down is only a few minutes waiting on generator start up.

The City of Athens graciously provides us with an internet connection, which allows us to run the APRS Igate and the Winlink RMS Packet Server.

The club call KG4FZR is managed by trustee Bob Miller, KG4FZR, who is the retired City of Athens Fire Chief, and also overseen by Chuck Ziegler, KI4ETT, current City of Athens Police Chief. Scott Duckworth, NA4IT, is the sysop and keeps a watchful eye on the system through a remote access via the internet, and by 24/7 monitoring the RF with his own APRS and Packet stations.

The radios for APRS & packet are fed into a repeater duplexer, and the on to a single antenna.

Additional info on packet mode can be found at http://www.mcminnarc.com/packet/packet.html.