Hi guys, Sorry to keep you waiting on the reasons against the masthead antenna. I should have included it in the original post. Randy pretty much nailed it. Here's Gordon West's answer to that. "Although you have a clever idea, I doubt the 3db gain -- double the radio's radiated power -- from a masthead antenna that's about 18 feet higher than the handheld's antenna will give much of an increase in range. The coax cable and connector losses will also negate any potential added performance. And don't forget that the cable itself will limit the area on board where you can use your handheld. There's also a small chance that the antenna connector might damage something inside your radio." Larry On Fri, 30 Mar 2007 18:09:31 -0400 "John Tyner" <tynerjr@md.metrocast.net> writes:
Larry, What was the reasoning against connecting the handheld to a masthead antenna? I've been thinking of doing this myself. ~ John Tyner M-15 #412 "Chimpanzee"
-----Original Message----- From: montgomery_boats-bounces+tynerjr=md.metrocast.net@mailman.xmission.com
[mailto:montgomery_boats-bounces+tynerjr=md.metrocast.net@mailman.xmissi
on.com]On Behalf Of Larry E Yake Sent: Thursday, March 29, 2007 11:53 PM To: montgomery_boats@mailman.xmission.com; nwpotters@yahoogroups.com Subject: M_Boats: VHF boost
I found something in the latest issue of Sail mag that is actually of use to small boat sailors like us.
In the "Ask Sail" section a skipper inquired about improving the range of his handheld VHF with a masthead antenna. Their expert (Gordon West) basically shot that down, but added the following:
"A better way to improve a handheld's performance is to get a longer antenna for it. Your local marine radio store (or go to www.hamradio.com) should sell 24-inch-long flexible antennas with an SMA connector. Get one for the 2-meter band, which is close enough in frequency to the marine VHF band. Mounting one of these antennas should give you twice the range that you'll get from the standard handheld antenna."
I don't think I would want a 24" antenna on my radio all the time, but it would be nice to have one to screw on when you need the extra range.
Larry Yake M17 #200 CornDog "In a power boat you get there faster. In a sailboat you're already there."
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I've never experienced coax cable and connector losses with my signal flags, Larry. t
I've worked as a system engineer for a major communications corporation for more years than I care to mention. Here's my analysis: First, are we using the same antenna, but in one case mounting it at deck level and in the other case mounting it at masthead level? If so, then all we are concerned with is the additional line loss. RG8-X type cable is a manageable size and has reasonable loss - about 4 dB per 100 ft at 100 MHz. Marine radio operates at 160 MHz, so losses will be a little higher, let's call it 5 dB per 100ft. (Don't use RG58 or Radio Shack cable or connectors. Buy quality, name brand, low-loss cable and get help if you're not sure how to install a connector. Weatherproof all connections.) How high is your mast? 25 ft? Then loss is only 1.25 dB + maybe 0.5 dB for additional connectors to allow removing the mast. Overall, I think you'd see an improvement. If you're using a handheld radio with a little helical whip antenna, then you'll see a big improvement. Those rubber antennas have a loss relative to a reference dipole of 6 to 10 dB. A 5/8 wave antenna will be close to the gain of a dipole reference. Even with line loss, you should see a net improvement of 3 to 7 dB. There is a case to be made that you would like your radio to work if you are dismasted. There is also the danger of undetected corrosion or damage to the antenna and line at the masthead where inspection is difficult. ----- Original Message ----- From: "Larry E Yake" <leyake@juno.com> To: <montgomery_boats@mailman.xmission.com> Sent: Friday, March 30, 2007 9:57 PM Subject: Re: M_Boats: VHF boost <<SNIP>>
"I doubt the 3db gain -- double the radio's radiated power -- from a masthead antenna that's about 18 feet higher than the handheld's antenna will give much of an increase in range.
<<SNIP>>
Keith is correct..........and you will see an improvement in the rig....... my 2 cents.... Bill KD5IUD........ham operator M17 - #251 M15 - #158 ----- Original Message ----- From: "Keith Diehl" <kdiehl@xmission.com> To: "For and about Montgomery Sailboats" <montgomery_boats@mailman.xmission.com> Sent: Saturday, March 31, 2007 12:14 PM Subject: Re: M_Boats: VHF boost
I've worked as a system engineer for a major communications corporation for more years than I care to mention. Here's my analysis:
First, are we using the same antenna, but in one case mounting it at deck level and in the other case mounting it at masthead level? If so, then all we are concerned with is the additional line loss. RG8-X type cable is a manageable size and has reasonable loss - about 4 dB per 100 ft at 100 MHz. Marine radio operates at 160 MHz, so losses will be a little higher, let's call it 5 dB per 100ft.
(Don't use RG58 or Radio Shack cable or connectors. Buy quality, name brand, low-loss cable and get help if you're not sure how to install a connector. Weatherproof all connections.)
How high is your mast? 25 ft? Then loss is only 1.25 dB + maybe 0.5 dB for additional connectors to allow removing the mast. Overall, I think you'd see an improvement.
If you're using a handheld radio with a little helical whip antenna, then you'll see a big improvement. Those rubber antennas have a loss relative to a reference dipole of 6 to 10 dB. A 5/8 wave antenna will be close to the gain of a dipole reference. Even with line loss, you should see a net improvement of 3 to 7 dB.
There is a case to be made that you would like your radio to work if you are dismasted. There is also the danger of undetected corrosion or damage to the antenna and line at the masthead where inspection is difficult.
----- Original Message ----- From: "Larry E Yake" <leyake@juno.com> To: <montgomery_boats@mailman.xmission.com> Sent: Friday, March 30, 2007 9:57 PM Subject: Re: M_Boats: VHF boost <<SNIP>>
"I doubt the 3db gain -- double the radio's radiated power -- from a masthead antenna that's about 18 feet higher than the handheld's antenna will give much of an increase in range.
<<SNIP>>
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participants (4)
-
Bill Tosh -
Keith Diehl -
Larry E Yake -
Tom Smith