Powerful Aircraft VHF Radio

[hellosailor]

OK, sell him a 5/8 wave antenna instead.

[Wotname]

Originally Posted by Pelagic

makes sense..... Only as good as the weakest link....So can anyone hazard a guess at what would be the approximate range of the 109's 10w at 8000ft?

At least 50 miles, maybe 80 miles, possibly 100 miles. This is based on experience of general aviation coms (7 to 12 Watts Tx power) flying overland and a base station antenna height of less than 15 ft. Perhaps over water you will do quite a bit better. Line of sight at 8000 ft is 126 miles. Of course being AM, atmospheric electrical noise may knock you back a bit, especially in the tropics.

I will check out the airband com on board the oil rig next week and ask what range they are getting with the helos - it is ~ 150 miles off shore and the birds are flying around 8 to 10 K ft. However it might be a few days (or weeks) before I can report back .

Originally Posted by hellosailor

.....................
Don't let them cheap out on the cable, either.

Exactly and unless others know of better coax (and readily obtainable), I would stick with LMR 400 Ultra.

I assume if they can build this ship, someone with be able to terminate coax properly - otherwise send me a return ticket

[Pelagic]

Originally Posted by Wotname

I assume ....they will be able to terminate coax properly - otherwise send me a return ticket

You know, that is probably one of the most original excuses i have heard a guy explain to his people at home as a reason to fly in to Subic Base... and with a little bit of interpretation... can be considered true...

Thanks again for the education I have a good handle on what to get.

Wotname, would be interested to know what type of antenna the oil rigs are using.

Also for clarification: The ICOM specs read:..
Output power : 36 W typ. pep (9 W typ. for CW)

So do I calculate potential range based at 9 W or 36 W?

[Wotname]

Originally Posted by Pelagic

You know, that is probably one of the most original excuses i have heard a guy explain to his people at home as a reason to fly in to Subic Base... and with a little bit of interpretation... can be considered true...

I do try to be original....sometimes...

Originally Posted by Pelagic

Wotname, would be interested to know what type of antenna the oil rigs are using.

Yes...understand...I am planning to scout out their setup in detail...Com, antenna, coax, range etc... I have full access to the radio room and pilot house...and the guys are pretty friendly if you show some interest in their job...mostly they are only thinking of when their tour of duty is up .

Originally Posted by Pelagic

Also for clarification: The ICOM specs read:..
Output power : 36 W typ. pep (9 W typ. for CW)

So do I calculate potential range based at 9 W or 36 W?

9 W. This is the amount of RF full carrier wave (CW) that is transmitted when the mic is keyed (but not modulated) and is the figure that best describes the power output of an AM transmitter.

I have forgotten the benefits of quoting the Peak Envelope Power (PEP) - if I ever knew it .

[svaletheia]

Originally Posted by Pelagic

Also for clarification: The ICOM specs read:..
Output power : 36 W typ. pep (9 W typ. for CW)

So do I calculate potential range based at 9 W or 36 W?

9W is the carrier output with zero input modulation, yes, but NOT the maximum power in AM mode. For that, its 36W. PEP = Peak Envelope Power. Since AM modulates a base carrier by amplitude, it increases the amplitude for the peaks and decreases it for the lows of the audio-frequency signal. The maximum power output by the AM signal, at the voice peak, is 36W. Think of 9W as the "average output power", more or less. Remember, its FM that transmits equal power to the carrier, its AM that varies the power output as its modulation scheme.

Originally Posted by Wotname

I have forgotten the benefits of quoting the Peak Envelope Power (PEP) - if I ever knew it

Many AM radios are rated at PEP, therefore the figure for output power comparison is probably most appropriately a 36W PEP comparable setup, not a 9W comparable setup. Good radio companies quote this because it is important to determine what the maximum modulation range of the radio is - this directly relates to the clarity of the voice signal on the AM scheme. A factor of 4 in power is a pretty damn good ratio - many AM radios cannot boast an average to PEP ratio of 4. Shoddy companies quote it because its the bigger of the two numbers.

But the figure for determining effective range is essentially 9W, as this is most analogous to the average output power of the radio.

And like many have said before, range won't be an issue for you.

I second the LMR-400 cable. Try to put exactly 4 connectors on it:

1. Radio to cable.
2. Cable to lightning arrestor.
3. Lightning arrestor back to cable.
4. Cable to antenna.

No more, you lose power with each connector and introduce a possible corrosion and signal leak point.

Shorter cable runs are always better. Do not forget the lighting arrestor, it should be mounted as close to the antenna as possible and connected to a solid ground (e.g. the mast if it is grounded or a superstructure ground rod of some nature).

[Wotname]

Originally Posted by Pelagic

....So can anyone hazard a guess at what would be the approximate range of the 109's 10w at 8000ft?

I have just unexpectedly been talking to rig transfer pilot and he quotes 50 miles for an average rig radio setup. Some of them have pretty poor radios and especially poor antennas and the range then drops to about 30 miles. The better setup ones are getting 70 miles.

This is at 5000 to 6000 ft.

[Wotname]

Originally Posted by Pelagic

.......

Wotname, would be interested to know what type of antenna the oil rigs are using.
......

I have just returned from the rig and I can report that their airband VHF antenna set up was bit sad - suffering from lack of maintenance IMO.

They have a simple 1/4 wave wire whip mounted on a steel bracket atop a 5 ft steel pole welded to the hand rail above the Pilot House. The bracket was the ground plane. The whip was bent about 20 degrees off the vertical (had been hit by something), the coax connector was very corroded and the 30 feet of RG 58 had seen better days.

But it worked and the radio operator reports a consistent 50 nm range.

Unless you have already chosen an antenna, this one looks very nice IMO
http://www.jotron.com/ai_files/jaybe...nna_890589.pdf

or any of these from Jotron
JOTRON

[m.swofford]

I'll try to make this crystal clear. You can't use an aircraft band radio for other than aviation use and only if you have a "restricted radiotelephone license" issued in conjunction with your student or higher pilot licence. Improper use of aviation bands is a very big deal whether they be vhf communication, navigation or especially concerning hf comm bands. Interference with normal radio traffic would jeopardise aviation safety and in no case is casual chit chat permitted on any aviation band by anybody, including pilots. We pilots report interference immediately to the controlling air traffic control center. Frankly I can't imagine what legitimate end you have in mind. Marine radios are not CBs either.

[skipmac]

Originally Posted by m.swofford

I'll try to make this crystal clear. You can't use an aircraft band radio for other than aviation use and only if you have a "restricted radiotelephone license" issued in conjunction with your student or higher pilot licence. Improper use of aviation bands is a very big deal whether they be vhf communication, navigation or especially concerning hf comm bands. Interference with normal radio traffic would jeopardise aviation safety and in no case is casual chit chat permitted on any aviation band by anybody, including pilots. We pilots report interference immediately to the controlling air traffic control center. Frankly I can't imagine what legitimate end you have in mind. Marine radios are not CBs either.

Not sure why you felt the need to jump in like this. If you go back and read the entire thread it seems obvious the original poster is quite aware of the regulations and restrictions and has every intention of complying. I saw nothing at all in the discussion that indicated the OP planned to use aircraft channels like a CB.

Perhaps you are not aware, there are numerous marine based operations that have extensive interaction with aviation and legitimate needs for communications. Lots of large yachts have helipads that frequently shuttle owners and passengers to the vessel, sometimes quite far at sea so comms between vessel and aircraft are important. This doesn't even touch on offshore oil rigs that have almost constant helicopter traffic flying crew and equipment to the rigs.

I do also believe the OP indicated he had already investigated the appropriate license for his intended use and had the green light.

[Zanshin]

This thread is over 4 years old, so the OP has either gotten in trouble for using the airbands or has not transmitted - in either case, this thread really is dead; but it did get me to look in my paperwork bin and find my old General Radiotelephone license and realize that I still had hair in that picture

[skipmac]

Originally Posted by Zanshin

This thread is over 4 years old,

Yes. This in addition to everything else I said.

Originally Posted by Zanshin

so the OP has either gotten in trouble for using the airbands or has not transmitted -

Since the OP is still posting on the forum at the very least he didn't get locked up.

[Wotname]

Originally Posted by m.swofford

I'll try to make this crystal clear. You can't use an aircraft band radio for other than aviation use and only if you have a "restricted radiotelephone license" issued in conjunction with your student or higher pilot licence. Improper use of aviation bands is a very big deal whether they be vhf communication, navigation or especially concerning hf comm bands. Interference with normal radio traffic would jeopardise aviation safety and in no case is casual chit chat permitted on any aviation band by anybody, including pilots. We pilots report interference immediately to the controlling air traffic control center. Frankly I can't imagine what legitimate end you have in mind. Marine radios are not CBs either.

Welcome aboard M.Swofford. Interesting first post and as presumably you are not a long lurker, we should cut you a little slack.

However I must endorse what Skipmac posted and add there are dozens if not hundreds of legitimate reasons for maritime users to have airband radios. I myself have installed more than several and all had appropriate regulatory approval and did the operators.

As for pilots and chit chat, I'm not sure what part of the globe you are in but
rest assured many pilots chit chat - especially on 123.45.

Stay around and get to know us all please before getting too worked up

[GordMay]

Greetings and welcome aboard the CF, m.swofford.

[a64pilot]

To put a marine band radio in an aircraft can be done, but it takes what is called a field approval, as I'm sure there is not STC for a boat radio, plus the weight and room for such an installation, required EMI, EMC testing etc., would run into some money. But yes, if you can afford a Helicopter and a boat it can land on expense I'm sure is negligible.
Much less hassle to put an aircraft radio in the boat.
As long as the radio is used to communicate with aircraft, I can't see the FCC or FAA even being concerned with it's use, I would assume the FSDO (flight standards district office) would recommend and support the installation as it would increase flight safety.

The stated purpose of 123.45 is air to air, it is the talk to your buddy freq.
Meet you up five fingers

[hellosailor]

"there are dozens if not hundreds of legitimate reasons for maritime users to have airband radios. "


I must have a limited imagination. I can think of one or two, but hundreds?


"Turn starboard to three four zero, you are two miles out from me. Prepare to drop pizza!"


What, your Dominos doesn't do airdrops at sea?