Many thanks to Matt (W6CSN) who shares the following post from his blog at W6CSN.Blog:
Rainy Day Activation
by Matt (W6CSN)
It’s late December and one of a series of winter storms is driving into northern and central California. The previous day, my plans for a combined Summits On The Air and Parks On The Air activation fell apart due to weather. Today most of the UTC day had passed with only light drizzle, and itching to get on the air, I hatched a plan for an activation at my nearby park reference K-7889, the Presidio of San Francisco.
Typically when activating at this park from the “East Beach” area, I will back into a parking space, setup the radio on the trunk lid and run the coax a short distance to a 17 foot vertical telescoping whip antenna which is clamped to a short steel post.
Today however, I chose to operate from inside the vehicle so both myself and the radio equipment would stay dry. Not wanting to leave the coax unsupervised where someone could trip over it, I deployed the Gabil GRA-7350T antenna with a triple mag-mount on the roof of the car.
The GRA antenna is a short, loaded vertical with the whip portion maxing out at about 8 feet in length. It works well on 20 meters, but it’s less of a compromise on higher frequencies. On 18 MHz, only a small amount of the loading coil is needed to achieve an acceptable SWR, so with the bands in pretty good shape I brought the Yaesu FT-818 so I could get on 17 meters.
There weren’t many spots for 17m on the POTA web site, but I posted my spot anyway and started calling CQ. It wasn’t long before KX0Y responded, followed by more hunters from across North America and Alaska. The Golden Gate Bridge was visible from my vantage point at the start of the activation, but as the rain intensified the bridge became enshrouded by the incoming weather front.
With 00 UTC approaching, the rain now coming down harder, and 13 QSOs in the log I called QRT. Rather than carefully stowing the antenna and mag-mount, I simply broke it down as quickly as possible and tossed it all the back seat since I would have to bring it inside to dry anyway.
The following equipment was used in this activation:
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- Yaesu FT-818 QRP transceiver
- Gabil GRA-7350T antenna system
- Triple magnet antenna mount
- CW Morse machined aluminum pocket paddles
- Rite In The Rain spiral notepad logbook
- Snazzy Zebra mechanical pencil with “shock absorber.”
Thanks to all the hunters that responded and made the activation a success.
73 de W6CSN.
Ha! It looks like we’re all enjoying those rainy POTA days! Thank you for sharing your field report with us, Matt!
Cheers,
Thomas
Well I admit, after watching your activation video with the TX-500 in the rain earlier that morning, by afternoon I’d decided to not let a little weather keep me off air! Even if I did have to operate from inside the car.
Whoazer! That antenna really worked it’s magic. Fantastic report Matt. And I get it… sitting in your vehicle, just makes sense sometimes.
72 de W7UDT
The antenna has really proved itself, I take it on every activation knowing that if my other antenna options don’t work I can always get out on 20 meters at least with the GRA-7350.
Yeah, it was kind of fun doing an activation nice and dry while the weather was blowing in.
Great antenna!
That was one of the parks I was thinking of activating while I was out there in Sept. I brought a QRP Labs QCX Mini and EFHW tuner from QRP Guys and went to K-0757 San Francisco Maritime National Historical Park to activate. Not as many trees as I would like, but I made it and got 3 QSOs before I had to pack it in for an emergency call from home.
Mike, I’m curious where did you setup your station in K-0757? It can be a challenging location. Here’s hoping you can return some day and get the activation.
I used the same antenna earlier this summer to activate from the end of Hyde Street Pier (with park staff permission).
https://qrper.com/2023/08/matts-low-profile-pota-activation-at-the-san-francisco-maritime-national-historic-park/
I was on the walkway a north of the Speaker Tower by Van Ness Ave. There are some benches there that I sat on facing Alcatraz. My first attempt was right on the edge of the park, but it blocked the path, so I shifted more in north of the tower in that curve. The antenna was thrown and hung at a low angle in the trees.
I know exactly where you were.
You definitely face a challenge as a QRP portable operator setting up for a POTA in K-0757.
Matt, looking at the Gabil product I found this
https://www.gabilradio.com/gra-gnt-antenna-mount
which may pair nicely with that whip antenna (or other vertical antennas) and allow to use it away from the car 🙂
Looks like that kit certainly gives you some options for creative deployment of the GRA!
Mike do you know what the threading is for the whip itself ? Is it metric or also 3/8-24 ? This antenna may be exactly what I am looking for, but I am always concerned about whips and possible replacements as that what typically breaks on these sorts of antennas (I have a lot of experience with broken Buddipole whips 😉 ) – Cheers Michael VE3WMB
Michael,
Not OP but an owner of this antenna—it’s a standard 3/8 stud at the feed point, but an M10 1.5 at the whip end. They do sell a replacement antenna on Amazon, and it’s essentially the same time as the MFJ-1898, and they might have their own replacement P/N.
I’ve also seen a couple folks buy a female-female threaded coupler and use a 17′ whip, also with male M10 threads, that are floating around on AliExpress, eBay, etc.
IM thanks for the response. I did manage to figure out that the top threading on the coil is M10X1.5. I ordered one of these antennas for my own use, including the optional shock-corded whip, which is really nicely made and looks very durable.
One thing that I haven’t seen discussed with respect to this antenna is the idea of adding on a short extension below the coil. This is of course only practical if you order the model that terminates in the 3/8-24 thread. Base loading is the least efficient way of loading a short vertical, simply because currents at the base of the antenna are at the highest and coil power loss is proportional to current squared. I have lots of Buddipole/Buddistick parts so my plan is to add on a short arm (~ 1 foot) below the sliding coil. This doesn’t add much additional weight or bulk and should be an improvement. Note that the only side effect of moving the coil slightly up the antenna is that generally more inductance is needed to match a given antenna length when the coil is moved away from the bottom, but I don’t think that will be an issue on 40m with this antenna.
Cheers
Michael VE3WMB
P.S. It is too bad that they didn’t make the whip threading 3/8-24. It is worth noting that the optional shock-corded whip comes with both M10 male to 3/8-24 male and M10 male to 3/8-24 female adaptors so it can be used with other mobile antenna parts.