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HF radios?

airguy

airguy

Unrepentant fanboy
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Has anybody here installed an HF radio and external antenna to an RV? I'm continuing my prep for longer legs and getting parts/pieces ready for eventual transoceanic hops outside of VHF range that would require HF comms. There are a variety of radios that will work, the big question seems to be the antenna, looking for ideas.

I have an avionics access plate just forward of my windshield that I could use to install about a 12" vertical standoff, and run an external random-wire antenna back to the top of the vertical stabilizer. Then I could power that antenna either from the avionics bay or from the tailcone location with an auto-tuner. I'm not a fan of the belly-mount idea with fixed gear, I'm not an RF propagation expert by any means but this seems like a bad idea with shadowing from the gear legs.
 
Greg

This guy came through Abilene on his around-the-world trip.
http://www.chasingthemorningsun.com/flight_log_1.htm
His HF antenna was attached to the fuse near the cabin, then to the trailing edge of his wingtip and to the top-forward leading edge of his vertical stabilizer. If you poke around on the website, you can get glimpses of it.

Our EAA chapter hosted him here for a couple of days. He wrote a book about his journey and was an interesting read.

Good luck on your planned trip. I'll be watching. ;)

Sam
 
A trailing wire worked well for the Lancair 4 that flew over the north and south poles.

The radio was the small ICOM with remote display, the radio itself and the remote antenna tuner mounted in the trail at the feed point. Some experimenting was required to find just the right diameter funnel (1? diameter or so) to put at the end of the wire as a ?drag shute? so the wire did not whip around. Length of wire was 20? - 30?. The tow point was designed as the breakaway point if it ever got snagged on the ground. It never did and he landing is some very weird places.

You will have to experiment with the tow point to make sure the wire says clear of the tail control surfaces.

Carl
 
As for concerns about the gear legs having an effect on propagation, don't worry about it. For most HF frequencies relative to an aircraft the size of an RV, the airplane is just a "blob of metal". RV gear legs would become meaningful as a director/reflector at about 2-3 times the highest frequency you would use for HF.

Trailing wire is one of the best ways to go for an aircraft of this size. I've installed HF antennas on slightly larger aircraft for use in ferry flights across the pond. In all cases the trailing wire provided better performance, and I only had one get snagged and it broke exactly as expected with zero structural damage. Wish I could say the same for the one strung from behind the canopy to vertical stab to wingtip. When it broke at the fuselage mounting point the loose end beat the tar out of the vertical stab and rudder.
 
Canadian_JOY said:
As for concerns about the gear legs having an effect on propagation, don't worry about it. For most HF frequencies relative to an aircraft the size of an RV, the airplane is just a "blob of metal". RV gear legs would become meaningful as a director/reflector at about 2-3 times the highest frequency you would use for HF.

Trailing wire is one of the best ways to go for an aircraft of this size. I've installed HF antennas on slightly larger aircraft for use in ferry flights across the pond. In all cases the trailing wire provided better performance, and I only had one get snagged and it broke exactly as expected with zero structural damage. Wish I could say the same for the one strung from behind the canopy to vertical stab to wingtip. When it broke at the fuselage mounting point the loose end beat the tar out of the vertical stab and rudder.
Click to expand...

The trailing wire idea is not a bad one - but I can't find any sources for reels to deploy or retract them, is there something you can share?
 
airguy said:
The trailing wire idea is not a bad one - but I can't find any sources for reels to deploy or retract them, is there something you can share?
Click to expand...

Not needed and adds complexity. Just hook it up to the tow point before getting in the plane. It drags on the ground as you taxi. Get some good quality #14 hard drawn copper antenna wire.

Carl
 
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