DIA
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737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 4:13 pm

The antennae cables (I'm assuming they are HF) can be seen between the leading edge of the tail connecting to the top of the fuselage of this 732.


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This is a current photograph...so these types of 732s still serve. What was this option...and why was this an option (in regards to placement of the antannae)?
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surfrider1978
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 4:18 pm

When I worked at LGB based WinAir in the late 90's, we had a 732 reg. N920WA that had one too. The only plane in the fleet that had one, and I always wondered the purpose of it too.
 
BR715-A1-30
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 4:26 pm

I remember, about 9 years ago, seeing a Nations Air 737-200 in GPT (N7375F), and it had an Antenna Cable (or two). I too wondered what it was for, as the DC-9 sitting next to it did not have one.
Puhdiddle
 
DaBuzzard
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 5:19 pm

HF comms have a much longer range than the vhf comms and so are used when the ac is operating out of vhf range, ie: trans oceanic routes, far north (Arctic), far south (Antarctic).

Don't know if they all use the cable type antenna or if there is another type.
 
na
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 6:02 pm

Many 737s were even retrofitted so up to today. Merpati from Indonesia is such a case. LAN Chile retrofitted a number of 732s after 2000 with these wire antennas. Most 732s with these Antennas are flying through remote areas in Africa or South America, or Indonesia.
Odd though that British Airways and sister airline British airtours received about 30 732 in the early 80s, of which the airtours aircraft only were fitted with these antennas.
Some 732s even have two wire antennas, Indian airlines aircraft for example.
 
nema
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 6:55 pm

Perhaps this thread should have been posted in the Technical area of the site
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iRISH251
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 7:04 pm



Quoting NA (Reply 4):
Odd though that British Airways and sister airline British airtours received about 30 732 in the early 80s, of which the airtours aircraft only were fitted with these antennas.

Not that odd, as these would have tended to operate to more distant destinations where their company probably did not maintain a company station. These machines may also have operated in oceanic airspace to destinations in SW Europe and North Africa, so HF would have been required for them to do that. In the pre-mobile phone days HF radio was used all the time to maintain contact with base and would have been particularly useful in the more far-flung places that charter aircraft tend to visit. Several Aer Lingus 737s had cable HF antennae and in recent weeks I saw an ex-NW Airlink BAe146-RJ-85 (N506XJ, photos elsewhere on the Net) with a cable attached for comms on its transatlantic ferry flight.
 
Viscount724
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 7:52 pm



Quoting DaBuzzard (Reply 3):
HF comms have a much longer range than the vhf comms and so are used when the ac is operating out of vhf range, ie: trans oceanic routes, far north (Arctic), far south (Antarctic).

The HF antennas were common on quite a few 737-200C combis (equipped for operation on gravel runways) used over the years by half a dozen Canadian carriers. As mentioned, they needed the HF antennas on routes to remote destinations in the Canadian Arctic region.


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I think radio communications in that area have improved in recent years as the HF wire antenna no longer appears on any recent photos of 737Cs used by carriers serving that area today. Looks like they were removed at least 15 years ago.


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EMBQA
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RE: 737-200 Antennae Cables Between Tail And Fusel

Fri Feb 29, 2008 8:01 pm

HF Antennas are used on many different aircraft even today. For the most part they are used on aircraft during delivery flights flying over long areas of open ocean or when flying over uninhabited areas. If you look at the tip of the horizontal stabilizer you can make out the HF Antenna on this REX SF340 as it starts its trip of the Pacific Ocean.....
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[Edited 2008-02-29 12:16:14]
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KELPkid
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 8:09 pm

Did anybody use the long wire style NDB antennas on the 737-200s? If so, it could also be an NDB antenna...on GA aircraft, in general long wire antennas are the NDB antenna, as GA aircraft are very rarely HF radio-equipped (and usually, when they are, it's a temporary installation for things like ferrying the aircraft across large bodies of water  Wink ). There are also blister-style NDB antennas for GA planes.
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surfrider1978
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 8:51 pm

https://www.airliners.net/photo/Winair/Boeing-737-2Y5-Adv/0020180/M/

Another odd antannae. Located just at the base of the tail.
 
EMBQA
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 9:52 pm



Quoting Surfrider1978 (Reply 10):
Another odd antannae. Located just at the base of the tail.

Ahhhhhhh.. that's a water drain mast.
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avioniker
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 11:30 pm

Drain mast on the bottom, ELT antenna at the base of the vert stab. Smile
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
avioniker
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Fri Feb 29, 2008 11:43 pm

The HF antenna is longer than the other antennas because of the wavelength. Lower frequency = longer waveform. That's where it gets its range. The longer waveform can bounce off the ionisphere and solid masses rather than being absorbed or distorted like higher frequencies' waves.

Use of a longwire allows for simple installation with little structural modification. The coupler(s) are installed in the cabin ceiling where they are easy to access and the wire can be installed with only two anchor points.
Newer aircraft use the leading edge of the vertical stab, or even winglets, as the antenna and the couplers are installed behind panels at the base of the stab. The coupler must be installed at the antenna connection.

The leading edge antenna is a newer modification that came with advances in electronic and structural technology along about the late '60s. Prior to that time the HF antennas were wires or probes measured to a fraction of the actual wavelength of the frequency selected. The coupler acts to multiply the length of the antenna reducing reflected power so the transmitter isn't burned out when it broadcasts into the antenna. Sort of like spitting into the wind.

That's the simplified version. . .
If you want more you have to sit through one of my less alertness inducing lectures  Smile
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
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HAWK21M
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Sat Mar 01, 2008 9:37 am

The older B732s especially P&WJT8D-9A/15A & prior had the HF antenna in this type,this was later replaced by the Antenna in the Vertical fin aft of the LE.
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DKCFII
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Sat Mar 01, 2008 5:45 pm



Quoting KELPkid (Reply 9):
Did anybody use the long wire style NDB antennas on the 737-200s? If so, it could also be an NDB antenna...on GA aircraft, in general long wire antennas are the NDB antenna, as GA aircraft are very rarely HF radio-equipped (and usually, when they are, it's a temporary installation for things like ferrying the aircraft across large bodies of water   ). There are also blister-style NDB antennas for GA planes.

I was going to mention the same thing. Is it possible that some of these antennas are for NDB purposes? All the planes I learned to fly on had these type of antennas and they definitely didn't have HF capability. I was also looking at a Lufthansa A340 yesterday going from DEN to MUN and I didn't see any HF antenna like that, and he was going to be flying over some remote areas. What are the requirements to have such a setup?

-Dan K
 
avioniker
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Sat Mar 01, 2008 6:25 pm



Quoting Avioniker (Reply 13):
Newer aircraft use the leading edge of the vertical stab, or even winglets, as the antenna and the couplers are installed behind panels at the base of the stab. The coupler must be installed at the antenna connection.

I'd say the 340 qualifies as a newer aircraft

 Smile

Whether or not HF is installed is purely a function of the desires of the aircraft operator at time of purchase or lease. They evaluate what their needs will be and equip the plane accordingly. An HF installation on an aircraft not provisioned can run well over $250,000. It behooves the purchaser to consider their needs carefully.
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
474218
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Sat Mar 01, 2008 7:20 pm



Quoting Avioniker (Reply 13):
Newer aircraft use the leading edge of the vertical stab, or even winglets, as the antenna and the couplers are installed behind panels at the base of the stab.

Actually the antenna is embedded in the panel.
 
avioniker
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RE: 737-200 Antennae Cables Between Tail And Fuselage?

Sat Mar 01, 2008 8:49 pm



Quoting 474218 (Reply 17):
Actually the antenna is embedded in the panel.

The composite panel assembly was a later development that saved a lot of money and engineering and significantly lightened the entire structure.

Just trying to keep it simple for the younger guys that don't remember when Eastern got their first 727's with the leading edge antenna.

I spent the better part of two years scouring boneyards for 27's with LE antennas to retrofit on older planes with the probes or no factory HF installed. It's almost a bolt-on swap once you convince the local FSDO you aren't trying to put one over on them and get them to sign the 8110's and 337's.

My favorite is the DC-9/MD-80/B-717 antenna.
How many of you can accurately tell what the antenna is on those?

 Smile
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533

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