W6CSN: Activation 72 of the Presidio of San Francisco National Historic Site

Many thanks to Matt (W6CSN) who shares the following post  from his blog at W6CSN.Blog:

Activation 72

by Matt (W6CSN)

Today’s activation of the Presidio of San Francisco National Historic Site (K-7889) was pretty standard for a mid-winter POTA outing. Normally, I wouldn’t bother to write it up on this blog. After coming here 72 times there is not much new to say about it. Nevertheless, maybe somebody will find value in this field report.

Even though the weather was dry this afternoon, the radio operating began in the car where I used the FT-818 to net 14 contacts on 17 meters. I must admit being warm while doing a POTA activation is not bad!

The Bencher is a breeze to operate on the center console.

After a while, the calls started to dry up so I extended the antenna fully to get on 20 meters, but the best SWR I could get was 3:1. I suppose the lack of good bonding of the coax shield to the car body, which I’ve read about in other blog posts on qrper.com, was responsible for the less than optimal antenna match.

After taking down the badly matched roof mount antenna , I flipped the car around and backed into the parking space to set up my usual 20 meter station on the trunk lid with the antenna clamped to a steel post.

The trunk lid is where I usually operate from when at this park.

At the same time, I switched radios to the Mountain Topper MTR-4B. Previously the current draw of the FT-818 had dropped the battery voltage to 12.6v, but with the lighter load of the MTR, the voltage rebounded above 13v. The MTR-4b is designed to accept 13v, something the other radios in the MTR series are not recommended for. However the SWR in this antenna configuration was 1.0 to 1 so I felt okay to run the radio at the full 5 watts with the higher voltage.

The Wolf River coil provides a good match on 40 meters.

Unfortunately, 20 meters wasn’t performing all that great, yielding a mere four contacts. The POTA website showed several JA’s activating parks on 40 meters, so I added the Wolf River coil to the base of the antenna in hopes of hearing them. Alas, no copy, so I put out a few CQ POTA calls of my own on 7.062 MHz. W6OOD responded from Southern California, but my report was not particularly strong. And, with the light fading I decided to call it a day.

QSO map by http://tools.adventureradio.de/analyzer

Activation #72 netted a total of 19 QSOs on three different bands, coast-to-coast. Not bad for an unremarkable Friday afternoon ham radio outing.

4 thoughts on “W6CSN: Activation 72 of the Presidio of San Francisco National Historic Site”

  1. Matt, nice to know I’m not the only one who swaps out radios during activations!

    Agree with comments on earth bonding when using mobile antennas – I’m about to start experimenting with a clamp on counterpoint too.

    Richard MM0RGM

    1. Using a radials or a counterpoise can definitely improve the match of roof a mounted vertical on your car. Although the extra wire can be problematic in high traffic areas.

      I hope your experiments yield good results and lots of QSOs!


  2. Thanks for the activation, Matt. I was glad to barely hear you from my truck (ATS-120a and FT-891) as I was driving home from work. It sounds like you were almost clear over my head but just caught me here in SoCal. I also use a bencher on the center console.
    I read Tom’s blogs and was surprised to see my call, so I checked my log. Thanks for the activation.
    Thanks, Dave Wood, W6OOD

    1. Hi David, if I recall, your signal was pretty solid. I rarely get on 40 meters because my antennas are very much a compromise there, toss in the QRP, and it’s not a recipe for huge success. But I am happy we were able to make the QSO!


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