Of all the
VHF and UHF amateur bands, the 33 cm (902-927 MHz)
allocation is generally the least used, because:
- There are NO off-the-shelf 33cm radios on the amateur
market, most likely due to the lack of international
allocations for this band.
- This band is shared with a plethora of industrial,
medical, and other
wireless services such as
sensing and control, and other
- With a few exceptions (namely Motorola Maxtracs and
Spectras), surplus commercial gear for 33cm is difficult,
if not impossible to modify for the adjacent ham band.
- Increased multipath propagation makes mobile and
portable operation in urban and mountainous areas more
Of all the
HF amateur bands, the 10M (28-29.7 MHz) allocation is
generally the least used, because:
- Decreased solar activity over the past few years
means that the Maximum Usable Frequency almost never
reaches this high.
- This band is very dependent on constantly fluxuating
solar activity, making regular nets or schedules on this
band frustrating at best.
- Much of the local activity on this band (especially
during the low end of the sunspot cycle) is on FM, yet
many older HF rigs do not provide this mode.
- Commercial low-band (30-50 MHz) equipment that can be
converted to this band is difficult to find and often
expensive, since the most frequently used channels are in
the top end of the allocation.
Which is why, in keeping with our
mission of exploring uncommon and
underutilized frequencies, we are working on a project to link these
two bands together! Project 33 will link a 33cm split-site FM
repeater to a 10M all-mode simplex tranceiver. So what can we do with
such an oddball system?
- As we move into the peak of the sunspot cycle (maximum solar
activity is projected for the year 2002), we will be able to work
world-wide DX from our portable and mobile UHF radios.
- We will gain the experience of developing customized circuitry
to control the 10M radio.
- We will be able to experiment with methods of minimizing 33cm
multipath, such as
- circular polarization
- Dual diversity antennas
- Multiple receiver sites
- Because the 33cm repeater will be split-site, we will be able
to place the RF equipment at the antenna to eliminate feedline and
duplexer losses, and thus increase overall system performance.
- The system will be available during disasters and other
communications emergencies as a backup area-wide communications
path, in addition to existing ARES and OES systems. In this vein,
we will experiment with NVIS (Near Incident Vertical Skywave) to
ensure reliable 10M regional coverage.
Because of the shortage of portable 33cm radios, we have decided
to make this a split-site system so that we can use our current
dual-band HTs. Many HTs will receive 33cm, but will not transmit in
this band. Therefore, we can transmit on the 70cm link frequency to
"cheat" our way into the system.
- Located at QTH of KQ6DY, about 100ft ASL
- Frequency - 902.??? MHz
- Micor 800MHz repeater receiver strip - mod to 33cm ham
Repeater/Link Controller -- built and ready for smoke
- Micor 460MHz repeater transmitter strip, 15W output - mod
to 70cm ham band
- 33cm circularly-polarized Antenna -- homebrew
- 70cm vertically-polarized Link Antenna
- Located at QTH of KK6XF, about 250ft ASL
- Frequency - 927.???
- Micor 460MHz repeater receiver strip - mod to 70cm ham
Repeater/Link Controller with digital voice ID and additional 10M
link controller circuitry -- hack
- Micor 800MHz repeater transmitter strip, 15W output - mod
to 33cm ham band
- ???? 33cm Power Amplifier -- kit
- 33cm vertically-polarized Antenna
- 70cm vertically-polarized Yagi Link Antenna -- homebrew
RCI-2950 10M All-mode Tranceiver -- hack,
schematic in hand, still looking for Tech Manual
- 10M horizontal Dipole Antenna -- homebrew
The initial phase of the 10M link controller will use the Ranger's
10 programmable memories. Future expansion will provide direct
frequency entry and scanning control.
Construction has started! Status of subsystem is shown in
bold italic. We hope to have a 33cm beacon on the air
by the end of 1997, with the complete 33cm repeater system active by
Spring, 1998, and the whole enchilada (including the 10M link)
working by Summer, 1998 -- just in time for the predicted upward
trend in solar activity!
last updated 12.31.97 by KK6XF