Richmond Amateur Telecommunications Society

RATS operates a Digital Mobile Radio (DMR/MotoTRBO™) repeater as part of the DMRVA system which covers most of Virginia.  This repeater went into service on May 30, 2014 with the generous assistance of Jay Lovelady KD4BPZ and Dave Meier N4MW.  This Motorola XPR8300 was originally placed in service on a backup UHF antenna at around 460 feet.  In December 2019, it became the primary RATS UHF asset and was relocated to an upgraded antenna at 680 feet.  

Before going on the air, repeater users should be familiar with the particulars of DMR operation, as well the RATS Repeater Rules & Policies, basic repeater etiquette, and some general talkgroup etiquette from our friends at DMRVA.  If you need help becoming familiar with DMR or have questions about operating procedures, please contact the RATS Technical Committee.  We will be happy to help in any way we can.

Questions about the DMRVA network, including requests relating to nets or special events on a DMRVA member repeater, should be directed to DMRVA.

All DMRVA repeaters are Color Code 1.  A list of current DMRVA talk groups is available here.  Note that some talk groups are static (always on) while many others are dynamic (PTT-activated).  Dynamic talk groups are only carried on the repeater for a period of up to 15 minutes after a local user has transmitted on that talk group.  Otherwise, you will hear no traffic on these talk groups.  Only one dynamic talk group can be active on each time slot at any given point in time, so before transmitting on one of these TG's, ensure other talk groups on the same time slot are not in use (DMRVA-supplied codeplugs have a "monitor all" channel in each zone for this purpose).

Please do not kerchunk the repeater to keep a dynamic talk group active.  If you have a special need for extended access to a talk group, consider the use of a DMR hotspot device.  When selecting a talk group for a QSO, use the smallest talk group which will maintain contact with the desired station(s) and use the "clear all" function to disconnect from a dynamic talk group when you are finished using it.

Above:  Map showing projected coverage of the W4RAT 443.5875 MHz repeater, generated using Radio Mobile Online by Roger Coudé VE2DBE

The repeater output (after the duplexer) is about 20 watts.  The antenna, a Commander Technologies 455-5N, is fed by about 750 feet of 1-1/4 inch hardline which is shared with the VHF analog repeater.  A UPS provides short-term backup power for the DMR repeater and Internet connectivity, and the entire RATS repeater system is serviced by a large diesel generator maintained by our host TV station.

Below are pictures of the rack containing the DMR repeater.

Front view of the DMR repeater

Above:  Front view of the DMR repeater


Rear view of the DMR repeater

Above:  Rear view of the DMR repeater

Richmond Amateur Telecommunications Society, Inc. (RATS) is a 501(c)3 non-profit organization. PO Box 70613, Henrico VA, 23255

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