Recently, on the nasota group, there was a discussion about designating an alternative 2m FM frequency for Summits On The Air (SOTA) use (instead of 146.52 MHz). The main driver for this is that 146.52 MHz can get busy with other radio traffic and/or a busy SOTA activation can tie up the calling frequency for a long time.
Rex KE6MT (SOTA W6 Association Manager) kicked it off with:
A friend of mine, George KJ6VU, has been talking with me and several others about the idea of an FM “Adventure Frequency.” It would be for more than just SOTA – other *OTA’s could also use it. There are other ideas to layer on top of it, such as tone signaling so that you don’t have to hear traffic you don’t want to hear, and repeater infrastructure for announcing someone’s on the frequency with a given tone, etc. But the core thing would be to decide on a frequency and really get it in use. The National Calling Frequency (146.52) can be great for a few contacts sometimes, but other times it’s problematic either because it’s being hogged or because nobody’s listening. Of course, this Adventure Frequency could have the same issues present themselves differently, but would alleviate some and pave the path for future additions mentioned above.
I have previously written about the challenges of using 146.52: The Use of 146.52 MHz
One important idea is to include the other “OTAs” in adopting this frequency, most notably Parks On The Air (POTA). Hence the name “Adventure Frequency,” and not “SOTA Frequency.” It is really about hams operating portable in an outdoor setting. Of course, like all amateur spectrum, this frequency must be shared with other users.
It may seem like a simple thing to choose a nationwide simplex frequency but VHF band plans are managed regionally. In particular, there is a mix of 15-kHz and 20-kHz channel spacings. (For more background on this see Simplex Channel Confusion on 2 Meters.)
After some discussion, the group settled on 146.58 MHz. There was some dialog around using CTCSS for signaling but nothing specific surfaced.
Some key points:
- The NAAF is 146.58 MHz.
- This frequency is in addition to, not a replacement for, the National Simplex Calling Frequency 146.52 MHz.
- Local usage will likely vary depending on needs.
- Program 146.58 MHz as The Other Simplex Frequency in your radio.
What does this mean to you?
Program 146.58 MHz into your radio and have it available. If you are doing SOTA (or POTA) activations, consider using this frequency, especially if you are in an area where 146.52 is used a lot. (I’ve already started using this frequency for SOTA activations near urban areas.)
73 Bob K0NR
I just took a look at local band usage and see that 146.58 has already been designated a secondary local simplex frequency. That means I’ve already programmed it into all my radios. Handy. Of course, we have more cows than people hereabouts so if I hear anything on national simplex I figure someone bumped the dial on their radio.
Well, I guess we are going to need to get those cows licensed.
Hi Bob,
In Arizona, the SOTA chasers and activators use 144.410 for 2m FM activity and a few different clubs that we know of use 146.580 for local simplex nets.
I find myself monitoring 146.580 more than anything else when at the qth or mobile.
The problem is that the AZ preference isn’t really known to people who don’t live here. Last year, while down in Tucson and monitoring .520, I heard a 0 call looking for sota contacts somewhere near Mt Lemmon. I think he said he was from Missouri and here for a week looking for some fun. I let him know about sota activity on .410 and he went off frequency where I am sure he was happy with the result. As you probably know AZ is really radioactive.
I am sure many will agree that a standard would be helpful.
Enjoy your day.
73
Dan
N7DSX
Dan,
It turns out I operated from Mt Lemmon about a year ago but I did know about the local practice of using 144.410 MHz. I also worked a number of stations on 146.52 MHz.
I don’t know how they chose 144.410 MHz for SOTA in Arizona but the ARRL band plan shows 144.30-144.50 as “New OSCAR subband,” See http://www.arrl.org/band-plan Anyway, too bad it is not appropriate for nationwide use.
VHF/UHF band planning is local which results in a lot of different approaches. I wish we could start over and do something more consistent nationwide but that ain’t happening.
The Western Washington Repeater coordination group (WWARA) has designated your suggested frequency as one of 8 channels 12.5 kHz narrow band digital channels below 146.500!
I am glad the ARRL linked me to this content in particular and your site in general. Well done! 73 de w0trr
Thanks, Timothy.
Charlie N7KN,
The proposed frequency is 146.58 MHz, which should align with the WWARA band plan. The ARRL Letter reported incorrectly that the frequency is 146.48 MHz.
Having said that, surely there is some frequency coordination body that has assigned 146.58 MHz to a repeater output or some other special use. That seems to be the nature of VHF bandplanning. 🙂
Genius! I’ve been waiting for this for many activations, .52 is buisy in the NY NJ area and mountaintop qrm can be rough.
Thanks, Dave.
I get a lot of comments that “146.52 MHz is dead, so no need for another frequency.” Usage of .52 varies dramatically across the country, mostly tied to population density but local habits come into play. Having the designated NAAF is another tool to use, based on local circumstances.
73 Bob
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There is already a 2 m FM simplex frequency in backcountry use: 146.460 MHz. It is commonly used by 4×4 owners to talk among themselves. I think this is a better option for SOTA and POTA operations.
73,
Bruce Prior N7RR
Hi Bruce,
The NA SOTA group did discuss the use of 146.46 MHz. Quite a few of the SOTA enthusiasts are also into 4×4 adventuring. There were some advantages and disadvantages to adopting .46 as the frequency but the consensus of the group was to find a separate frequency.
Bob