Dunestar 600
$$$··
| Frequency | 1.8-29 MHz (six switched HF band-pass filters: 160, 80, 40, 20, 15, 10 m) |
| Bands | 160m, 80m, 40m, 20m, 15m, 10m |
| Power | A passive band-pass filter, not a transmitter. Rated for use with 200 W PEP transceivers; it passes the operating band and strongly attenuates other bands. |
| Modes | switched 6-band HF band-pass filter array (for multi-transmitter / SO2R interference reduction) |
| rf in | SO-239 from the transceiver |
| rf out | SO-239 to the antenna (or amplifier) |
| band control | DB-9 connector for band switching, selectable positive (default) or negative (12 V) relay logic, for automatic or manual band selection |
| power req | Passive in the signal path; only the band-switching relays use 12 V logic over the DB-9 connector. Do not switch bands with RF applied. |
Solves a specific contest problem neatly: it keeps a strong nearby transmitter on one band from overloading another station's receiver, with one compact box covering all six contest bands. Rejection is strong (40 dB-plus on harmonically related bands), insertion loss is low (about half a dB), and the DB-9 band-control input allows automatic band-following so the right filter is always selected.
It is a specialist accessory for multi-transmitter and SO2R stations - a single-radio operator gains little from it. It is limited to 200 watts, so it sits before an amplifier rather than after it, it covers only the six traditional contest bands (no WARC, no 6 m), and bands must never be switched with RF present.
The Dunestar 600 is a six-band switched band-pass filter that prevents inter-station interference in multi-transmitter and SO2R setups, with strong rejection, low loss and automatic band switching, all in one small box at the 200-watt level. It is essential gear for contest and field-day multi-op stations; a single-radio operator generally does not need it.
The Dunestar 600 is a switched band-pass filter array built for one job: letting two or more stations on the same site operate on different bands at the same time without wrecking each other's reception. When a transmitter on, say, 20 meters is keyed a few feet from a receiver listening on 15 meters, the strong signal and its harmonics can overload that receiver's front end. The Dunestar 600 places a sharp band-pass filter in each radio's signal path so each station passes only its own band and heavily rejects the others.
Inside one box are six individually tuned three-pole filters, one each for 160, 80, 40, 20, 15 and 10 meters. Insertion loss in the passband is low, typically 0.5 to 0.7 dB, while rejection is strong: the manual rates 40 dB band-to-band, and independent measurements show at least 40 dB on the sub-harmonic band and 35 dB on the first harmonic. A DB-9 connector handles band switching and can be set for positive (default) or negative 12-volt relay logic, so the unit can follow a radio's band data automatically or be switched manually. One operating rule applies to any such filter: never switch bands while transmitting.
It uses SO-239 connectors for RF in and out, is rated for 200-watt PEP transceivers (so it goes before any amplifier), and covers the six traditional contest bands rather than the WARC bands or 6 meters. It sells for around $230 to $260.
It is essential equipment for a multi-transmitter contest or Field Day station, and complements other SO2R gear such as an Array Solutions PowerMaster II meter or a FlexRadio Tuner Genius XL. A single-radio operator generally has no need for it.