Society of Ether Explorers

San Francisco



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 license-free wireless services such as video links, internet providers, remote sensing and control, and other OEM applications.
  • 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 difficult.





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.

System Overview

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?



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.

33cm Receiver Site

33cm Transmitter Site

10M Link

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.

Project Schedule

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