[VHFcontesting] FM antennas

[nosigma at aol.com]

Sean,

This is longer than I wanted so bear with me.  Call me at 703 678 6795 if you want I would enjoy talking to you, much more efficient.

I use to run a triband omni along with beams spending about 15 minutes at the top of each hour on the omni.  I found that the omni wasnt worth it.  The "high gain" omni, a cx-333 was used for close in work thinking I was missing stations due to my beams narrow azimuth beam width.  The cx-333 had a narrow elevation beam width which was the price paid for high gain, worse as frequency went up.  I work from elevations around 4500-5000 ft.  The low power omni stations I was working that were close in (within 25 miles) were actually stronger on the beam side and back lobes than on the omni.  The 2m beams sloppy lobe structure has advantages.  Reason being that the omnis on both ends were not getting into each others main lobes consistently, especially when ridgeline diffraction is involved.  The 30 to 45 degree elevation pattern of the beam antenna let me work close in stations below me more efffectively and I could still reach out and touch fm stations 200 to 250 miles out when pointed at them.

I love my tight and precise M2 440 and 220 beams but those are qsy bands that I use after peaking on 6m or 2m.  I see the "sloppy" pattern of my cushcraft 2m beam as a bit of an advantage. I bet a third of my contacts start on the side, and especially the back lobe of the cushcraft.

My beams are all 9 to 12 foot booms and I dont move after setting up unless lightening it bears chase me off the mountain.

If you work locations within 100 to 150 miles line of sight from population centers a set of 6 foot boom beams which are easy to handle might be a better bet for fm.  Spend 10 or 15 minutes calling cq on fm pointed at the population centers AFTER you exhaust ssb.  You wont get any new multipliers (unless its a really bad day) but you will wake the dead on simplex.

Here is a crazy thought (I am going to get flamed for this, its ok, I will learn from it)......if your short beams have at least 3db more gain than you ssb antennas AND the gain is flat with frequency you can always rack then over 45 degrees and try them on both fm and ssb to see how they compare.  Good low loss multiplexers are way easier than coax band switches and prevent you from blowing up power amps late at night when you get punchy.

Your thoughts appreciated

73
John
KM4KMU

Sent from AOL Mobile Mail

On Wednesday, November 29, 2017 Sean Waite <waisean at gmail.com> wrote:
Since we're always thinking of the next station improvement, I've been
thinking about the best way to implement FM in the rover.

We've found that it's worth carrying the gear. We don't get many contacts,
but they are out there and having the ability to make them on demand does
get us points. Right now, I have a 2/70 vertical that is used for FM, just
a mobile whip. In January for our run 'n gun I'll probably move to a
triband whip.

For the stop and shoots, though, we'll be better set up to run beams. We
have a couple of the small Arrow yagis available that wouldn't be too
difficult to strap onto a mast and have a v-pol beam available for the FM
radios. Small LPDAs like the Elk satellite antenna are also another option.

This would give us positive gain on FM...but i'm not sure it's worth it. FM
contacts are mostly opportunistic, either a periodic call on 146.52 or just
hearing someone and grabbing the mic real quick. The directivity a yagi
would give us might blind us to some of the nearby stations calling (though
the arrows aren't particularly narrow) if they are off the side of the
beam. The other drawback is that it'll take a little longer to set up if
we've got another beam or three to attach to the mast and cable up.

What do other people do? Maybe better to have some always-connected, more
efficient verticals on the roof the car and sacrifice a bit of gain?

Looking forward to your thoughts.

73,
Sean WA1TE
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