After reading a review of the Efactor Dual-Band 144/432 MHz antenna in the June 2017 issue of QST, I decided to buy one for myself. This antenna is omnidirectional and horizontally polarized for SSB, digital and CW.
I have tentatively planned for Saturday, 29 July 2017 to be my first activation using this antenna. I plan to be on Mount Tamalpais (W6/CC-063), just across the Golden Gate Bridge from San Francisco. I would be most appreciative if any chasers in the Northern California area with SSB capability on these bands would watch for my spots and/or listen for me on that day.
I like omnidirectional here in California for VHF SSB because many summits here have population centers within reasonable distances in multiple directions. Plus, this particular antenna seems interesting and I wanted to try it out.
I’d like to note that the official SOTA summit is the West Peak, not the (easy to access) East Peak with the road and fire lookout.
As far as I can tell, everyone has activated the wrong peak so far. I think that there are places to get into the AZ on the West Peak without going into the closed areas, but I haven’t had a chance to go check it out myself. I marked some areas on this map: SOTA Mt Tam Activation Zone - CalTopo
I think a case could be made that the East Peak is higher (it looks higher from nearby peaks), but that’s not what shows in the SOTA database.
I think you may be correct about prior activations. The East Peak with the Fire Lookout and marked trail is the obvious, but wrong place for a SOTA activation.
The East Peak is where the radar golf ball is located, on the road just below the radar installation you will see a stub of a fire road that goes uphill toward the radar installation. I back into that fire road and hike (short hike) up the fence surrounding the radar installation.
Not a lot of room, but enough for a 2m/70cm activation. I have also used a telescoping tapped antenna for 6M and 2M SSB. Although due to this location in the activation zone VHF/UHF propagation to the north is limited; you could put a roll up j-pole on a 25’ mast to get propagation to the north.
BTW - I have climbed both the East and West and the East is just a few feet higher than the West. I was told that it was actually a bit higher before it was leveled to build the radar installation. I agree that from Hwy 101 the Easy Peak looks higher. GPS will get you to the correct activation spot!
Oops, I should have said the West Peak is where the radar installation is situated, and that the West Peak is just a few feet higher than the East. KB1KXL’s map pinpoints the stub of the fire road that I consider the best access to the activation zone. Joe AA0BV
Thanks for the video. Glad to see the history of this location.
I think this is a video of the Mt. Tamalpais Middle Peak. At several points in the video a golf ball shaped radar dome is visible, not very far from but separated from the middle peak. The East Peak and SOTA activation zone is located at the radar dome with the activation zone extending down toward the road.
From my own personal experience, the east peak definitely seems to be the higher of the two. In my own opinion, that should make it acceptable to activate from it, especially since they are clearly the same mountain. I thought the AZ was based on vertical distance from the summit; is there also maximum “horizontal” requirement (for lack of a better term)? The two peaks are in close proximity to each other, plus there are no other nearby summits that come close to their elevation.
The W6 ARM says they used peaklist and listsofjohn to get the initial list of peaks, but since then it looks like they’ve only used listsofjohn which says West. From the views I’ve had on recent activations in Marin, East looks higher.
The only requirement, having worked out which peak is the higher, is that the activation zone cannot include land that is connected to that peak via a dip of more than the activation zone definition (25m in vk, maybe 80ft in USA?)
Put another way, if you travel on the most elevated path from the highest peak to the lower one, the point where that path first dips below the higher peak by any more than the 25m (or 80ft) defines the outer border of the activation zone.
So if the dip between the two peaks is only say 24m then the lower peak would be included in the activation zone. If it’s more than 25m/80ft then the lower peak is just a parking area.
The horizontal separation does not matter.
This is based on my understanding of the prominence rules. Subject to being overruled by a more elevated authority.
I did some searches at the USGS Geonames database. They consider Mount Tamalpais a “ridge” feature and give the elevation of the center point (saddle). You need to search for “west peak” and “east peak” in Marin County, California.
They publish elevation data from the National Elevation Dataset.
East Peak: 2569 feet, 783 meters
West Peak: 2546 feet, 776 meters
The links to the Geonames feature pages are a little wonky. The instructions for cleaning them up don’t match the URLs in the current site. Let’s hope these work.
Or we could activate both on the same day for double the fun and one of them would surely be acceptable to SOTA. I would be interesting for the coordinator of W6/CC to provide the elevated response.
I do not recall my exact results but I did visit both peaks on the same day and to my surprise the GPS on my Th-D72A showed the East was about 3-4 feet lower than the west.
The history lesson in an earlier post shows that until the radar installation the West peak was 31 feet higher - they moved a lot of dirt to flatten the top - so on historical data that would make the original height of the West Peak the highest point.
Personally, I am glad that there are volunteer leaders to identify and certify the peaks for us - all I truly want to do is climb summits and play with radios!
Looking at Google Earth and using the polygon fill method, it looks as if the West Peak is about 1 m higher than East Peak. The saddle between is well below the activation zone limit, so it can only be one peak or the other. I guess that the SRTM data used by Google Earth might be near its resolution limits… Interesting issue. Until some data gives cause to change the SOTA location, it is clear that the West Peak is the one to activate at present for SOTA.