Papakura Radio Club inc. 1 Great South Rd Papakura Ph. 09 296 5244

National System Northern Frequencies

 
 
 

National System Frequency Changes - commencing over Anzac Weekend 2005 (April 23/24/25), repeaters on the National system are being moved up in frequency to remove a significant source of interference from short range devices. 1. Why do we have to change? In 2003, the Ministry of Economic Development (MED) created a General User Radio Licence (GURL) for Short Range Devices (SRD), on frequencies between 433.05 MHz and 434.79 MHz, occupying almost all of the 433 to 435 MHz repeater input frequency range. As a consequence many repeaters (and the National System) are suffering increasing interference from these devices.  Interference to the National System is particularly annoying, since all of the National System repeaters turn on when any one of them is triggered by a SRD. After considerable discussion, the only practicable solution is to vacate that part of the 70cm band occupied by SRD's and in particular, move all the National System repeaters to higher frequencies in the 70cm band. 2.  The New Plan, 2005 FMTAG, after extensive study, proposed a two-pronged approach - relocating the National System 70cm repeaters "up" the band by approximately 800kHz, using frequencies above 434.79 MHz and relocating local 70cm repeaters to lesser-used SRD frequencies.  A number of factors were considered, including ATV use and “propagation overshoot lock-up” - caused by the indiscriminate mixing of inverted and non-inverted repeaters on the same frequency, especially during periods of enhanced tropospheric ducting.  The existing National System frequency plan (first created in 1987) made provision for 72 stations (36 repeaters and 36 ULS), on 15 frequency pairs. With the move up in the 70cm band, only 7 or 8 interference free frequencies are available at the top end of the band.  Therefore, co-channel interference is likely to increase when all of these stations have to be accommodated on seven frequency pairs. 3.  How does it affect you? If you have a crystal controlled 70cm radio, you will need to get new crystals.  The new frequencies of the National System repeaters in the Waikato, Auckland, Whangarei and further north are as follows:      Auckland repeater              434.875 MHz transmit 439.875  MHz receive      Brynderwyn repeater         434.950 MHz transmit 439.950 MHz receive      Bay of Islands repeater     439.975 MHz transmit 434.975 MHz receive      Doubtless Bay repeater    434.900 MHz transmit 439.900 MHz receive      Edgecumbe repeater         439.975 MHz transmit 434.975 MHz receive      Hamilton repeater             439.975 MHz transmit 434.975 MHz receive      Kaimai repeater                434.850 MHz transmit 439.850 MHz receive      Rotorua repeater              439.925 MHz transmit 434.925 MHz receive      Whangarei repeater          439.925 MHz transmit 434.925 MHz receive   Auckland  Balclutha Bay of Islands  Belmont Blue Duck Brynderwyn Christchurch Blue Duck Brynderwyn Edgecumbe Egmont Hamilton Kaimai Kapiti Mount Erin Murchison Nelson Rotorua Saddle Hill Wairarapa Waitaki Waitomo Wanganui Whangarei Wharite 439.875 434.850 439.975 439.875 434.850 434.950 439.875 434.850 434.950 439.975 434.900 439.975 434.850 439.925 434.850 434.950 439.925 439.925 434.800 434.950 434.900 439.925 439.875 439.925 439.975 The following from InfoLine... 1st May 2005   Issue # 94 The current status of the National System changeover at the time of issue of this issue of HQIL is:  Brynderwyn, Bay of Islands and Far North - waiting arrival of crystals (due any day now). Once the crystals are on hand, frequency changes will be implemented progressively over the next three weeks, beginning with Brynderwyn, then Bay of Islands, then Far North. Klondyke. Waiting arrival of crystals. Once on hand, the new frequencies will be put on air with filters re-tuned. (UPDATE... should be operational Sunday May 15, 2005) From Klondyke, the link to Kaimai, Rotorua and Edgecombe will not be changed to the new frequencies until October. Amateur stations who use the National System from these sites will not have National System access until mid-October. Egmont (Taranaki) – The equipment was removed for frequency change and re-tuning last Tuesday 26th April. Because of limited access to this site, the equipment will not be re-installed for another three weeks. Te Aroha, Napier, Gisborne. Work is underway and will be completed once the new crystals are on hand. The National System will not be fully linked until Egmont back on air. The same applies to Rangitoto. Mount Erin – The duplexer and repeater will be removed for the changeover tomorrow. Crystals are due in the next day or so. Kapiti – Operational on its new Frequencies – nobody to hear yet!  Wellington (Belmont) – Awaiting the arrival of crystals for this site. Once on hand, the site should be operational almost immediately. Nelson – the intermediate site Saddle Hill is waiting crystals that are due anytime. The Nelson local repeater equipment was removed today  Sunday 1st May and should be back in service next weekend.  Murchison – This site is expected to changeover within the next month. Its change is dependant upon a service visit by the site owners. Blue Duck – The conversion is complete, and operational on new frequencies. Christchurch, Dunedin – The conversion complete, operational on new frequencies. Readers will note the huge co-ordination effort and planing that has been required for this changeover. My thanks to ZL1TGC, ZL2TAR, ZL2SX, ZL2HD and ZL2TVM for assistance in compiling this report. - ZL2BHF Ed

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Last revision: May 01, 2005

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