Voice Repeater FAQ

We have switched over to our new VHF simulcast system. Please note that frequencies and tones are different than the old system. Check the Repeaters page, or continue reading below, for updated information.

If you are here and all you are looking for is a “How should I program my radio” guide,  scroll to the bottom of this page and look at John Butler’s KF6GNI suggested programming chart.

What is a voice repeater? A voice repeater is an automatically controlled amateur station that facilitates voice communications between other amateur stations, that are separated by distance or terrain. Repeaters do this by receiving incoming signals on one frequency and re-transmitting audio from the received signals on a different frequency. Repeaters do this by using special filters to separate the received and transmitted signals, called duplexers. Repeaters are usually installed where they have wide receive coverage areas. Repeater users listen on the repeater output frequency, and transmit to repeater’s input frequency. Most repeaters require a sub-audible access tone (CTCSS) to transmitted on the input frequency, to re-transmit a signal from a user.

What is a simulcast system?  Simulcast is the simultaneous operation of two or more transmitters with overlapping coverage on the same frequency. This means that several repeaters operating on the same frequency are deployed to cover the area required. In our world that would be north, south and west portions of Marin County. By combining three repeaters into one system, Big Rock, Mt Tam and Mt Barnabe, we will dramatically improve our coverage area. In our system, we have different access tones (CTCSS) for each repeater in the system, but all transmitters are linked, so any received signal by one of the repeaters, is retransmitted by all three.

So, isn’t that what we had before? Well, not exactly. What we had was one repeater, on Big Rock, with multiple receivers spread around the county. That was good for being heard by the repeater, but not so good if you wanted to hear the repeater. Replacing the satellite receivers with a full repeaters will improve both transmit and receive performance in those areas.

The Timeline: On Saturday June 1, 2013 we took the first big step by upgrading the Big Rock repeater, making it the first member of the simulcast system. The new Big Rock repeater is now operating on a new frequency of 146.700 MHz, minus offset, with a CTCSS tone of 203.5. That’s the same access tone as the old Big Rock, only the repeater frequency has changed. Mt Tam went online Saturday June 8th, 2013 also on 146.70 MHz with a tone 179.9. The last site to become part of the simulcast system was Mt Barnabe, on 146.70 MHz with a tone of 167.9 which was completed in July 2013.

Where did the old 147.330 go?  The old Big Rock frequency, with a changed CTCSS tone, has been relocated to the west peak of Mt Tam in Building 402, where it will function as a stand-alone repeater.  147.330 went live on Mt. Tam on 6/10/2015, and has great coverage into Mill Valley, west into Stinson Beach.  Users should not continue using the backup repeater on San Pedro Ridge.

What’s working today?  All 3 sites VHF Simulcast sites are operating today, as are the stand-alone UHF repeaters, which were not affected by this upgrade.  The 147.330 VHF repeater (PL 179.9) on Mt. Tam went live, with new equipment, on 6/10/2015. The back-up VHF repeater on 147.330 remains live, but should not be used, unless the high-level site on Mt. Tam West Peak is down.

Any future plans for changes? We are planning enhancements to the Simulcast system, adding more receive sites (one enhancement has been approved, to date). We have purchased and are planning to install a Yaesu Fusion (digital) in place of the UHF repeater on Mt. Tam (443.250 MHz). There is a firmware update for the Yaesu Fusion repeater, which is a factory installed update. We will update the webpages as we implement changes.

What is a digipeater? A digipeater is a store-and-forward device used in APRS and Packet modes.
A digipeater receives and stores data packets, and after a short period re-transmits the information, on the same frequency.

Here is the new configuration:

The Simulcast System Three repeaters all on a transmit frequency of 146.700 MHz, Minus Offset
Big Rock Ridge, tone 203.5 – Up
Mt Tam, tone 179.9 – Up
Mt Barnabe, tone 167.9 – Up
Mt Tam West, tone 192.8 – Future

Stand-alone VHF Repeaters 147.330 MHz, Plus Offset
Mt Tam (Building 402), tone 179.9, Status: Up
San Pedro Ridge, tone 173.8, Status: Stand-by

Stand-alone UHF Repeaters
UHF 443.525 MHz, Plus Offset, Tone 82.5, San Pedro Ridge, Status: Up
UHF 443.250 MHz, Plus Offset, Tone 179.9, Mt. Tam, Status: Up
[We have purchased and are planning to install a Yaesu Fusion (digital) in place of the UHF repeater on Mt. Tam.]

Here is a suggestion for memory channel programming from John Butler, KF6GNI.

Marin VHF voice repeater systems:

Ch. 1 146.700 MHz – tone 203.5 Big Rock Ridge Simulcast System – Linked
Ch. 2 146.700 MHz – tone 179.9 Mt. Tam Simulcast System – Linked
Ch. 3 146.700 MHz – tone 167.9 Mt. Barnabe Simulcast System – Linked
Ch. 4 147.330 MHz + tone 179.9 Mt. Tam West Peak Stand-Alone Repeater – Preferred High-Level Site
Ch. 5 147.330 MHz + tone 173.8 San Pedro Ridge Backup Repeater – Low Level Site
Presently Ch. 1 , Ch. 2, Ch. 3, Ch. 4, and Ch. 5 are operating
Ch.5 SHOULD NOT BE USED after Ch. 4 is operational [6/10/15]
All other combinations of frequency and PLs for MARS’ Repeaters are now obsolete and should be deleted.

Updated: 12/26/2016