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Old 19-05-2018, 08:25   #1
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Connecting my handheld vhf to mast antenna

Is there a simple way for connecting my Garmin handheld vhf radio to the vessels masthead antenna. Something like an interface coupling that will thread into the PLl259 connecter at one side and the smaller diameter threads on top of the handheld allowing me the option of not using the rubber duck antenna and gaining better transmission and reception with the unit. If this type of connector doesn't exist maybe someone can suggest dedicated connector type to install on coax?
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Old 19-05-2018, 08:41   #2
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Re: Connecting my handheld vhf to mast antenna

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Is there a simple way for connecting my Garmin handheld vhf radio to the vessels masthead antenna. Something like an interface coupling that will thread into the PLl259 connecter at one side and the smaller diameter threads on top of the handheld allowing me the option of not using the rubber duck antenna and gaining better transmission and reception with the unit. If this type of connector doesn't exist maybe someone can suggest dedicated connector type to install on coax?
Yes, you can do this easily.

Your handheld probably has what is called a "female SMA" connector. The rubber ducky will then have a male SMA. On some radios the male connector is on the radio, so you will have to check.

Assuming the typical connectors, you want a male SMA to SO-239 adaptor (the SO-239 is the female mate to the male PL-259). I would do this through an intermediate length of thin (flexible) coax cable, otherwise you risk tearing the SMA jack off the radio.

Here is a link to a pre-made adaptor: https://www.amazon.com/DHT-Electroni.../dp/B00COW5E3A

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Old 19-05-2018, 08:45   #3
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Re: Connecting my handheld vhf to mast antenna

Simple and cheap. The connector on your handheld is known as an SMA. Many variations of SMA exist, but this is a plain vanilla type and the handheld has a Female gender. So you probably want an adapter cable that has a male UHF (PL-259) to male SMA;

https://www.ebay.com/itm/SMA-Male-to...Cym9nlDgmmK0PQ

I would get the 6 foot version.

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Old 19-05-2018, 08:49   #4
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Re: Connecting my handheld vhf to mast antenna

If you get the 6 inch cable, there's going to be a lot of stress on the SMA male connector lifting the weight of the UHF connectors and larger cables.
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Old 19-05-2018, 08:54   #5
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Re: Connecting my handheld vhf to mast antenna

Thanks looks like just the ticket, am I correct in my assumption the time they handheld into the mask stop antenna should significantly increase reception and transmission?
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Old 19-05-2018, 08:55   #6
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Re: Connecting my handheld vhf to mast antenna

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Thanks looks like just the ticket, am I correct in my assumption the time they handheld into the mask stop antenna should significantly increase reception and transmission?

Yes. Very significantly.
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Old 19-05-2018, 09:42   #7
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Re: Connecting my handheld vhf to mast antenna

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Originally Posted by TreblePlink View Post
Simple and cheap. The connector on your handheld is known as an SMA. Many variations of SMA exist, but this is a plain vanilla type and the handheld has a Female gender. So you probably want an adapter cable that has a male UHF (PL-259) to male SMA;

https://www.ebay.com/itm/SMA-Male-to...Cym9nlDgmmK0PQ

I would get the 6 foot version.

Chris
I agree with the longer cable if there will otherwise be stress on the radio connector. Six feet of the coax used in the jumper will give you very roughly 0.6 dB of loss, which is pretty good. I wouldn't go any longer if you can avoid it.

So cburger, will you be connecting to the existing cable with the PL-259 connector on the end? If so, you need a female UHF (SO-239) at the end of the jumper, or a UHF barrel connector that will join the two UHF male plugs.
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Old 19-05-2018, 10:54   #8
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Re: Connecting my handheld vhf to mast antenna

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Thanks looks like just the ticket, am I correct in my assumption the time they handheld into the mask stop antenna should significantly increase reception and transmission?
Great to have this connector as a back up if the vhf or battery bank fails. But this is no replacement for a proper vhf radio.
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Old 19-05-2018, 12:51   #9
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Re: Connecting my handheld vhf to mast antenna

A rule of thumb with dB:

3 dB = a doubling or -3 dB = a halving of power (watts)

10 dB = X 10 or divide by 10 power.

20 dB = X 100 or divide by 100 power

Generally, without instruments to measure, in communications systems, either VHF FM, or SSB, empirically speaking, it takes a change of 3 dB to notice any difference.

So, except in very expensive high-performance systems, (many TV and FM broadcast stations use coaxial cable that cost $30 per foot and more, as well as $50K and more for antennas) ...

Don't sweat the small stuff. And 0.6 dB is small stuff.

Now, here's why handhelds have poor range.

1. They're low power, like about 3 watts.

This is -9 dB compared to 25 watts which standard radios transmit.

2. They have inefficient antennas. (if interested ask)

Estimates vary for the "rubber duck" antennas, but are generally considered to be -6 to -9 dB reduced from a typical mobile antenna.

3. When held 5 feet over the cockpit floor, let's say 7 feet over the water, the distance to horizon is 1.4 x sqrt (7) = 3.7 miles.

For a mast top antenna at 35 feet: 1.4 x sqrt (35) = 8.3 miles.


So, transmit power and antenna efficiency is about -17 dB lower than a standard VHF FM radio and antenna. AND due to height reduction, the line-of-sight distance is much less.

When a handheld is connected to a mast-top antenna, line of sight distance is the same, and antenna efficiency is improved significantly.

Now we're only left with the transmit wattage penalty, about 9 dB.

There will be a considerable improvement.

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Old 19-05-2018, 13:58   #10
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Re: Connecting my handheld vhf to mast antenna

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Don't sweat the small stuff. And 0.6 dB is small stuff.

[...]

There will be a considerable improvement.
Yes on all counts. 0.6 dB is very small stuff. I've used similar jumper cables for an Iridium satphone connection, to transition from the heavy, low-loss cable to the handheld phone. At the Iridium frequency (about 10x the marine VHF frequency), the attenuation of the small cable is a real factor. Not so much in this case.
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Old 19-05-2018, 14:06   #11
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Re: Connecting my handheld vhf to mast antenna

Thank you all for your replies here
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Old 19-05-2018, 14:41   #12
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Re: Connecting my handheld vhf to mast antenna

If I want to make up the pigtail myself who makes the highest quality connectors suitable for the marine environment
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Old 19-05-2018, 14:56   #13
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Re: Connecting my handheld vhf to mast antenna

All SMA and SO239 connectors will be on for Marine environment. But terminating SMA is not something an inexperienced person can do well. The cable is usually tiny. Much safer (and probably cheaper too) to buy the pigtail adapter online.
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Old 19-05-2018, 21:00   #14
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Re: Connecting my handheld vhf to mast antenna

Many of the things I've learned over the years were based on what, in the business world, is called "Use of the available." If no one made it, unless you were into the new-fangled space exploration, one would review as many catalogs as possible. I poured over the WM catalogs endlessly. Guess I didn't have anything else to do. There are those very same catalogs now ONLINE. They show all the bits and piees needed to do what you want. Good luck.
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Old 20-05-2018, 09:24   #15
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Re: Connecting my handheld vhf to mast antenna

Can you just do that? Connect a handheld to a better aerial and expect better reception etc.?

I am not an expert but I thought the device would be "pre-tuned" to its standard aerial, small as it is.

Any experts?....

Thanks.
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