The opening of five (5) new frequencies for operation in the 60 meter band holds much interest for amateur radio operators. As such, the question “Can I operate on this band with SGC equipment?” is being asked frequently. First, let’s look at the FCC’s proposed rules as presented in FCC Document 03-105 approved on 29 April, 2003 and available for download on the FCC web site on the Office of Engineering and Technology web page at www.fcc.gov/oet
The proposed addition to the Part 97 rules says:
An amateur station having an operator holding a General, Advanced or Amateur Extra Class license may only transmit single sideband, suppressed carrier, (emission type 2K8J3E) upper sideband on the channels 5332 kHz, 5348 kHz, 5368 kHz, 5373 kHz, and 5405 kHz. Amateur operators shall ensure that their transmission occupies only the 2.8 kHz centered around each of these frequencies. Transmissions shall not exceed an effective radiated power (e.r.p) of 50 W PEP. For the purpose of computing e.r.p. the transmitter PEP will be multiplied with the antenna gain relative to a dipole or the equivalent calculation in decibels. A half wave dipole antenna will be presumed to have a gain of 0 dBd. Licensees using other antennas must maintain in their station records either manufacturer data on the antenna gain or calculations of the antenna gain. No amateur station shall cause harmful interference to stations authorized in the mobile and fixed services; nor is any amateur station protected from interference due to the operation of any such station.
Let’s deal with the requirements of this paragraph one by one:
Allowable Frequencies: The SG-2020 as delivered is restricted to the existing amateur bands. The transceiver can be modified to allow transmission from 1.8 to 29.7 Mhz by removing a jumper. The SG-2000 is delivered capable of transmitting on this frequency. SGC Smartuners are not restricted and will tune antennas in this range. Amateur Radio operators are always responsible for their frequency of operation. Once the SG-2020 is modified or when using the SG-2000, you must restrict your operation to amateur bands only unless you are 1) licensed for another service and 2) are using the SG-2000 in a service for which it is type accepted.
Bandwidth Requirements: The SG-2020 and the SG-2000 transmit bandwidth filters are within specification for the new channels. Page 119 of the SG-2000 manual graphs the frequency response of the SG-2000.
Frequency Selection: It is important to note that the frequencies specified are at the CENTER of the allowed bandwidth and that only UPPER SIDEBAND is allowed for transmission. In order to stay within each channel, amateurs should tune BELOW the specified frequency. The NTIA has recommended tuning 1.5 kHz BELOW the center frequency. We recommend tuning 100 Hz up from this point. An important aspect of tuning into the 60 meter band will be frequency stability. The SG-2020 will be stable within 3 ppm per 10 degrees C change in temperature, but it will require a warm-up period to be stable enough for such a narrow channel. Depending on the temperature of the environment, the SG-2020 should be allowed to warm up for 15-30 minutes.
Antenna Gain: The SG-303 & SG-307 antennas should show a gain of approximately –1 to –3 dBd in this frequency range. ANY gain figure though for any antenna is highly dependent on installation. In particular, STEALTH antenna installations will be very dependent on exactly how the antenna has been put together and what is in it’s environment. A single wire loop wound as a square with 20 foot sides, oriented vertically at 30 feet above a perfect ground would have a gain of approximately 0.5 dBd at these frequencies. Other configurations will produce different gain figures.
STEALTH Kit Antennas
As you might imagine, no figures have any meaning, even in a theoretical sense, if a STEALTH kit antenna is not built exactly the same way we modeled it. Further, the local environment will change the gain figures. You should develop gain figures for your exact configuration. However, we can provide some representative figures for a single turn loop composed of 80 feet of wire in a 4-sided configuration and fed at the bottom center.
These figures were developed from a model of the antenna as described above and provide an order of magnitude estimate for the gain in Free Space. Placing the same antenna 30 feet up over a perfect ground yields the following gain figures:
As you can see from a comparison of these tables, the nature of the ground, the height of the antenna, and many other factors will affect the gain. You should be careful to analyze the antenna as you have constructed it so that you have an accurate basis for your log entry
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