FM radio Aerial

General Discussion and Questions regarding TF72 and Ship Modelling
Post Reply
HelloSailor
Committee
Committee
Posts: 140
Joined: 31 Jan 2010 10:24
Fleet Base: Gulf Waters
My Ship Yard: HMAS VAMPIRE ( 1980 ) with pre 1980 armament additions
USS MISSOURI BB63 - post 1984 configuration
HMAS Duchess ( Post WWII ) Daring Cl Destroyer
Location: Woodcroft SA

FM radio Aerial

Post by HelloSailor »

Hi All , Can someone advise me as to whether or not it is Ok to cut the aerial wire, and insert a male/female plug . This is on a 36Mhz Futaba Transmitter . This is so that the superstructure can be removed off the deck without any interference of having the aerial wire restricting how far it can be located from the hull.
Cheers, Jim.
PS : NO , its not my system :no: :no:
User avatar
RussF172
Life Member
Life Member
Posts: 1049
Joined: 08 Feb 2010 08:53
Fleet Base: Hunter Central
My Ship Yard: USS WINSTON S. CHURCHILL (DDG-81)
HMAS HOBART (DDGH-39)
HMAS CANBERRA (LHD-02)
HMAS ADELAIDE (FFG-01 - 1990)
HMAS HUNTER (FFG-???)
HMAS ARUNTA (FFH-151)
HMAS BRISBANE (DDG-41) Perth Class Post Mod.
WRS RUSHCUTTER (A-51) Weapon Recovery/Training/Drone launch ship
Location: Uralla, NSW
Contact:

Re: FM radio Aerial

Post by RussF172 »

Hi Jim, I've done it and it seems to fine with no loss of signal as far as I can tell. An electronics expert might say otherwise.
User avatar
SlatsSSN
Club Member
Club Member
Posts: 1413
Joined: 21 Jan 2010 10:25
Fleet Base: Gulf Waters
My Ship Yard: Fleet - in service and under construction

Submarines:
HMS Talent S92 - Trafalgar Class SSN (James Slater)
USS Columbus 762 - Improved LA Class 688i

Merchants:
SMIT Japan Harbour Tug - (James Slater).
Vivienne Venezia - Harbour Tug.

Warships: (Under construction) -
HMAS Anzac -150 FFH (2007)
HMCS Forest Hill -K486 Flower Class Corvette
HMAS Stuart DE48 (James Slater)
HMS Cavalier D73
HMCS Fraser DDH233
Location: Adelaide

Re: FM radio Aerial

Post by SlatsSSN »

So long as you preserve the original antenna length that connects with your plug you should be fine. Also make sure you have a good clean electrical connection with the aerial wire to the plug.

We sub guys do it all the time. i.e. With the RX inside the water tight cylinder, the shortened aerial is soldered to a lug nut that fits over a bolt that runs through a bulkhead in the water tight cylinder and is secured by a locking nut. The bolt runs through the bulkhead of the water tight cylinder with the remaining aerial wire connected to the wet side of the bolt.

The bigger question in skimmers (surface ships) is why would you want to?
I'd be more concerned about mounting the RX and aerial in 2.4GHZ high in the model than I would 36 MHZ.

Whilst the rule of thumb we all hear is the higher you can mount a FM RX aerial the better, how much better is moot. 36MHZ RXs aerials do not need to be mounted in air or for that matter high. Case in point my subs maximum operating range on 36MHZ at 100m horizontal distance where I can't see it - is 5m vertical distance underwater. This is where the aerial is!! (Range test done at Central Coast Sub regatta with assistance from others).

So as far as I'm concerned mounting the RX high in the model for FM frequency is pure myth. I think you'd have to be pushing extreme ranges beyond the safe point of navigating your model for it to make any difference.

So 36MHZ works fine simply mounted high in the hull with the RX aerial strung out below deck level. FM doesn't have the same line of sight problems that 2.4GHZ has.

Cheers

John
He who dies with the most toys, just dies...you can't take it with you.
kimwhite
Club Member
Club Member
Posts: 413
Joined: 05 Feb 2010 18:32
Fleet Base: Victoria
My Ship Yard: HMS Heather (Flower Corvette 1942, under construction), HMS Glamorgan 1981 (under construction)

Re: FM radio Aerial

Post by kimwhite »

I would agree with John on this. I was originally going to mount my aerial for Invincible actually high up between the masts, like on the full size ship. After taking some advice on this I decided to leave the RX in the bilges, and the aerial is simply stretched out to its full length and duct taped to a thin strip of wood, and laid flat along the inside of the hull at about waterline level.
When Invincible had her first sail last weekend she was operating about 200 metres out into the Lake and still in radio contact, so obviously the aerial setup is fine.
As John says, if a model submarine can still pick up signal underwater us surface operators should be able to get away with anything as long as we leave the aerial at its original length.
cheers
Kim
HelloSailor
Committee
Committee
Posts: 140
Joined: 31 Jan 2010 10:24
Fleet Base: Gulf Waters
My Ship Yard: HMAS VAMPIRE ( 1980 ) with pre 1980 armament additions
USS MISSOURI BB63 - post 1984 configuration
HMAS Duchess ( Post WWII ) Daring Cl Destroyer
Location: Woodcroft SA

Re: FM radio Aerial

Post by HelloSailor »

Hi John & Kim , Thanks for your input. As I mentioned , it is not my vessel , but for a gentleman I met last week who is building a 1/128
" Bismark " & was concerned about the aerial wire up into the mast restricting the distance when removing the superstructure. In Mighty Mo , I have done almost what you have done Kim , & run it along the inside of my combing for my superstructure & don't have any issues with signal loss . I mentioned this to the person concerned & I think he will go this way.
Cheers, Jim
Post Reply