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1-10 of 27 messages
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Mars Antennas
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by KE7UAF on June 8, 2008
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I recently applied for membership to Army MARS, and I had a few preliminary questions regarding antennas.
Since the MARS frequencies are all off the amateur bands, do most people make their antennas or use commercially made antennas? This goes for both HF and VHF/UHF antennas. Would your standard amateur antennas work for operating out of band?
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RE: Mars Antennas
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by W3LK on June 8, 2008
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Eric:
<<do most people make their antennas or use commercially made antennas? This goes for both HF and VHF/UHF antennas.>>
The average VHF antenna needs no modification for MARS usage; it's broadband enough. As for HF, the answer is both. Most commercial antennas can be used on those MARS frequencies that are just outside the amateur bands with the use of an antenna matcher (sometimes called an antenna tuner). Frequencies not close to amateur allocations ( more than 250kHz away) generally require separate antennas (mostly dipoles) cut for the specific frequencies involved.
A very popular option is the B&W Terminated Folded Dipole. This antenna generally has a 2.5:1 or less SWR over it's entire operating range. It is less efficient than a single-band dipole, but it is excellent for the frequency hopping often done in MARS operations. This is the very purpose it was designed for - military communications on multiple frequencies without the need for any antenna matching device. There is nothing to prevent you using a tuner with it to keep the SWR lower, if you are running a solid-state rig. If you are using a tube amp following the rig, virtually all tube amps will handle a 3:1 or higher with no problem.
I normally drive a B&W with an AL-80A (running about 500w) for all MARS operations. It's mounted as a very shallow inverted V with the apex at 15' and the ends at 12' for an NVIS pattern. I have no problem covering a 400+ mile operating radius with the installation.
I have also used my Butternut HF6V for MARS for longer hauls down into the deep South and into the Mid-West and Texas.
Even though you are joining Army MARS, Welcome Aboard! :)
Lon - NNN0OOR (Former MDE SMD, Deputy SMD, Assistant For Net Operations)
Southern New England Navy-Marine Corps MARS
Proudly Serving Those Who Serve
http://bwantennas.com/ama/fdipole.ama.htm
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RE: Mars Antennas
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by KE7UAF on June 8, 2008
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Right now I've got a G5RVjr with a MFJ-993b automatic tuner. I also have a hustler 6btv but I haven't put it up yet. I've also got a Diamond X510HDM for 2m/70cm and a Cuschraft Ringo for 6m, but I doubt they'll be much use.
I've been doing some research and reading on the forum and I'm thinking about looking into the Navy MARS instead. I'm mostly interested in learning and getting some training, as well as just more reason to get on the air. With this in mind, would you have any specific recommendations?
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RE: Mars Antennas
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by W3LK on June 9, 2008
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Eric:
The G5RV/tuner combo might work OK. All you can do it try it. The same with the Hustler; try it and see what happens. :)
As for joining Navy MARS, I'll be happy to continue that discussion via email, rather than on the forum. I try to keep discussions about the different services off the forum. Despite the same basic operating procedures, there are definite differences between the services.
Lon - NNN0OOR (Former MDE SMD, Deputy SMD, Assistant For Net Operations)
Southern New England Navy-Marine Corps MARS
Proudly Serving Those Who Serve
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RE: Mars Antennas
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by KE7UAF on June 10, 2008
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Somehow I managed to unsubscribe from this thread. Sorry for taking so long to respond.
My email is huntley.eric.a@gmail.com, I didn't see yours listed anywhere or I would have emailed you.
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RE: Mars Antennas
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by W3LK on June 10, 2008
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Well guess what? It ISN'T. :(
majorlk@att.net
73,
Lon - W3LK
Naugatuck, Connecticut
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RE: Mars Antennas
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by W4LTX on June 17, 2008
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I use an alpha delta DX-CC for the amateur and MARS bands with an autotuner in the feedline.
Welcome to Army MARS.
God bless,
Pudge AAR3RF
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RE: Mars Antennas
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by W4FID on June 18, 2008
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I have used a Buddipole not even 10 feet high but physically adjusted for the MARS operating frequency I wanted. Had a delta loop 22 feet on a sidefed with an SGC237 coupler successfully on the Army MARS nets above 75 meters. Also the MFJ 1788 hi Q loop will tune anywhere from 7 to about 22 MHz and it's a resonant antenna that will work nicely even as low as about 10 feet high and great if in the clear. Some MARS nets are in that range.
If you can physically do it and the MARS nets you want are on one or only a few close frequencies a dedicated dipole in the clear is great.
Mobile whips don't seem to do too well. Most wil be tough to tune very far outide the ham band and at best they are a big compromise in efficiency so that's probably a last choice.
73
John
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RE: Mars Antennas
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by N9ESH on June 24, 2008
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You find some great ideas and some good pointers here.
http://www.netcom.army.mil/mars/training/docs/DOCUMENT%20NUMBER%201%202007%20REV%201.pdf
It’s the Army Antenna Seminar.
73,
Jim
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