Lower Cork Harbour APRS "Fill-in" Digipeater, EI4HQ-1

Page 1 of 1. July 2019.

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On May 4th 2019, I began experimenting with a low power "Fill-in" APRS digipeater for the Cork Harbour Area. The purpose of a fill-in digipeater is to help /M (mobile), /P (portable) and /QRP (low power) stations to make the first "hop" to a regional digipeater. I've set up EI4HQ-1 to also fill-in coverage gaps around the lower Harbour i.e. for areas that are shaded or blocked from the regional repeaters due local terrain. These areas include the south side of Great Island, the east facing slopes of the Monkstown and Passage West areas and the low lying Raffeen area. The key to a good fill-in digi is that it has good ears i.e. the receiver side is sensitive, and it has a voice that's just strong enough to be heard by a regional repeater but no more i.e. the transmit power is only just high enough to ensure a good link to a regional digipeater.

Early tests of the additional coverage provided by EI4HQ-1 (May 2019).

The hardware consists of an AEA PK-88 TNC, a Kenwood TH22e handheld transceiver and a Watson W50 2M/70cm 5/8 over 5/8 collinear that's mounted outdoors at an elevation of 88 metres above sea level. EI4HQ-1 transmits using just 30 milliwatts (the lowest power the TH22e will do). Testing since May has confirmed that it's enough to link reliably with the Southern Ireland Repeater Group digipeaters at Mullaghanish - EI2MGP-2 - and at Faha, Co. Waterford - EI2FHP-2. As should be the case for a fill-in digipeater, EI4HQ-1 digipeats "Wide1-1" only and beacons every 20 minutes [beaconing frequency reduced from 10 minutes to 20 minutes in April 2020 to reduce interference to NOAA satellite reception at EI4HQ]. These settings combined, ensure EI4HQ-1 has minimal impact on the national APRS frequency (144.800MHz).

Tests since May have confirmed much improved coverage around the Lower Cork Harbour area.

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