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Old 15-03-2009, 16:39   #1
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Antenna choice

Antenna choice

Given the two antenna choices (I already own both), which would be better.
Both are Shakespeare and both are 3db gain:
The 5400-xt. A four foot rail mount (so rail height) with RG8x wire or,
The 5215. A 3 foot wire whip antenna (on the top of the mast) with RG58 wire.
THX in advance

Shakespeare Marine Antennas Specifications: Galaxy Little Giant™ 5400-XT VHF Marine Band

Shakespeare Marine Antennas Specifications: Shakespeare Squatty Body® 5215 VHF Marine Band
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Old 15-03-2009, 17:04   #2
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Which boat?

The higher up antenna (either one) will outperform the lower one.

I'd lose the RG58 coax in favor of RG8X for a smallish boat with a short mast or RG213 for a tall mast.

Bill
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Old 15-03-2009, 17:09   #3
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Best is the 5400-XT at the mast head. It is a true dipole so doesn't need a ground plane.

In order to fit it up there, you need to put a mount on top of the mast. Next, cut it's cable and put a connector on. Now you can connect the long cable with a coupler and put it in adhesive lined heatshrink. If your long cable is the 8x type, you can use a direct splice connector with less insertion loss.

We have the 5400-XT 64' up with RG-8U cable and it's truly amazing.

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Old 15-03-2009, 17:43   #4
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My understanding is that better coax - as Bill suggests - helps a lot when masthead mounting. Maybe more important than the antenna choice.

Bill, I'm facing an upgrade myself and was thinking that RG213 would be a good choice for the coax but then noticed that LMR-400 is only 10% more expensive. Is this even better in the VHF frequencies?

Carl
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Old 15-03-2009, 19:48   #5
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Carl,

Yes, the LMR400 has lower attenuation at marine VHF frequencies (about 1.4db per 100 feet). But, it uses special connectors, usually crimp-on.

RG-213 has an attenuation of about 2.4db per 100ft, or about 1db more than LMR400. However, unless you have a very tall mast you're likely to use less than 100', so the attenuation difference would be less than 1db, i.e., not noticeable. And, RG-213 takes standard PL-259 connectors which, when properly fitted, make a very tight, water resistant connection.

So, I'd use RG213.

For interior use on SSBs, I like RG-214 which has a double-braid which helps to reduce RFI 2 ways (from the transmitter to other electronics on board, and to the receiver from other electronics on board).

Bill
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Old 15-03-2009, 20:55   #6
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Thanks - good advice. Hadn't thought about connectors yet...

Carl
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Old 16-03-2009, 00:50   #7
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FWIW, RG 393 is pretty hard to beat (except for the cost )
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Old 16-03-2009, 04:58   #8
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To give a straight answer without technicalities

the 4ft aerial should be a better aerial than the 3ft.

If they are located in the same position go with the 4ft.

If the 3ft is at mast head, and the 4ft on the rail, there is no question that the 3ft will seriously outperform the 4ft.
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Old 16-03-2009, 09:30   #9
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Thank You Talbot!

And thank you Btrayfors and S/V Jedi
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