Tararua Main Range
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Technical information - the small print.

The radios used are HF SSB sets, 1w PEP output, 2 channels.

WMRS is allocated a channel in the 90m band (3345kHz USB). The base station callsign is ZLJG and portables are allocated the same callsign with a serial number added. On air the "ZL" is usually omitted for brevity. The second channel fitted is 3261kHz USB used to contact bases in the south island - see Other Providers.

The key feature of HF signal propagation is that the signals are reflected by the ionosphere at a height of around 250km above the earth's surface. Thus the signals radiated by the sets travel up to the ionosphere and are reflected down again, hopping over mountains and other obstacles on the way. This contrasts with VHF and UHF signals which pass through the ionosphere without reflection. Cellphones are therefore limited to line-of-sight transmission paths to the cellsites.

Base stations use high power (100 watts) to provide a strong signal. The transmit power of the portables is limited by the battery capacity to about 1 watt. Thus the transmission path from base to portable is more reliable than the reverse direction. To make the best of the low power it is necessary to erect the aerial as high as possible, using the full length provided. (If the base station is having trouble hearing you, check the aerial first!) The sketch below shows a well erected aerial.

Aerial setup

Effective coverage from the Wellington base station is from Arthur's Pass to Tongariro and Urewera National Parks, although sets have regularly called in from Stewart Island to the Bay of Islands.

Overall reliability has been around 98%.

SR3 radioSR3
Condor/Codan radiosCondor
MRS1 radioMRS1