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😭
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
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 😎
Young at heart - slightly older in other places 😉 cheers Doug Grant me the Serenity to accept things I can't change, the Courage to change things that I can, and the Wisdom to know the difference!