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>> Home > Forum > Electrical Related > Futaba antenna
Futaba antenna
(356 views)
Author Message
Hugh
(Sub-Lieutenant)





Forum Posts: 13
7th May 2017 07:22  
>> Permalink
mdlbt.com/28263

I have a Futaba Attack 2ER system installed in my Fireboat. Through my own haste, stupidity, the antenna on the R122JE receiver was cut, about 1" from the receiver. I know the antenna/aerial must be kept to a specific length. Does anyone know if it is possible to join the 2 ends together, or replace the antenna? If neither of these is recommended, does anyone know where I could buy a new receiver. I have had no luck, so far, in Oz😭

Yax
(Chief Petty Officer)





Forum Posts: 2
7th May 2017 07:57  
>> Permalink
mdlbt.com/28264

Just strip the insulation off both pieces and solder them together then insulate the joint I have done it many times.

Haverlock
(Fleet Admiral!)





Forum Posts: 386
7th May 2017 08:14  
>> Permalink
mdlbt.com/28265

So long as the new antenna length is the same as the old no problem. You can cut the wire and replace with a length of piano ( music ) wire if you wish ( glue a bead on the end eye protection).

The big no no is to coil the length up.


"that's not a bug its just an undocumented creature."

Sir Terence David John "Terry" Pratchett, OBE (28 April 1948 - 12 March 2015)
Dave M
(Fleet Admiral!)





Forum Posts: 1228
7th May 2017 10:18  
>> Permalink
mdlbt.com/28281

Hi Hugh
There are R122JE receivers on E-bay but if I remember correctly they came in different frequencies. 27Mhz and 40Mhz - mine were stamped on a panel at the back of the Rx.
Current offerings are about £16 plus postage but that could be costly to you.
A new 2.4Ghz combi (Tx + Rx) set can be had for not much more and will work with all your ESC's and servos and doesn't require any crystals. I would expect there are local suppliers to you so postage should not be a problem.
Older 27Mhz equipment is becoming harder and more expensive to source and crystals are no longer easily available in all frequencies. I know there are many who wish to continue using their trusty equipment but the problem is it is entering into the collectors market and market forces are driving up the prices.
As someone who started out making my own Tx/Rx kit initially with valve and all the way up to a 4 channel transistor Tx/Rx I have changed gear many times. I usually pass on my sets to new club members to help them get started but have kept samples of some so I can still test any non working kit.
If you repair the aerial as suggested your set should be good for another several years and if it's working there is no need to change.
Cheers
Dave


Live long and prosper

Dave
RNinMunich
(Fleet Admiral!)





Forum Posts: 597
8th May 2017 00:19  
>> Permalink
mdlbt.com/28326

Hi Hugh, strip both ends. Twist the wires around each other and solder. Cover the joint with heat shrink sleeving. I cut the antenna of all my receiver and fit a small 2mm plug and socket so I can take the RX out without destroying half the ship.
This was essential with my U Boat as the antenna is led out of the pressure hull through a waterproofed (epoxy sealed) hole in the bow. Topside the remaining wire was fitted with another plug an socket, so I could remove the whole sea-deck for servicing, and stretched over the conning tower and down to the after deck just like the real ones.

Plus or minus a cm or so won't make much difference. Wavelength at 27MHz is about 11 metres and at 40MHz about 7.5m. So our antennas are working at about 1/16th of the wavelength. This is normally compensated (a bit!) inside the RX with a coil which increases the effective length that the RX input sees. My first boss always told me "RF is a black art!" 😉 Maybe if you try to beat the physics, but it took me around the world! Cheers Doug 😎


"Retirement is when you stop living at work -
and start working at living/boat modeling!" 舰队的海军上将 😉 Doug
RNinMunich
(Fleet Admiral!)





Forum Posts: 597
8th May 2017 01:04  
>> Permalink
mdlbt.com/28330

Oh Jeez, it's 2 am again😆
Good night everybody, sweet dreams and happy modelling 😎


"Retirement is when you stop living at work -
and start working at living/boat modeling!" 舰队的海军上将 😉 Doug
figtree7nts
(Fleet Admiral!)





Forum Posts: 318
8th May 2017 01:50  
>> Permalink
mdlbt.com/28334

Good Night!


"Fair winds calm Seas"
Hugh
(Sub-Lieutenant)





Forum Posts: 13
11th May 2017 01:18  
>> Permalink
mdlbt.com/28613

Thanks Dave, for your advice. Will sleep soundly now.
Cheers
Hughie👍

Hugh
(Sub-Lieutenant)





Forum Posts: 13
11th May 2017 01:20  
>> Permalink
mdlbt.com/28615

Thanks Yax,
I thought of doing that, but lacked confidence.
Cheers,
Hughie👍