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View Full Version : 2.4 GHz 'DSM' antenna length.



G Doggett
05-24-2009, 04:58 PM
I am about to switch to Futaba FASST for all my boats but am a bit worried about the occasional report of radio problems due to the receiver antenna being masked by carbon fibre hulls or water spray from rooster tails etc.
I am aware that the antenna wire is shielded for most of its length so that in fact only the unshielded bit on the end is actually the antenna.
This exposed portion must be a tuned length, so my question is can this be extended in multiples of this tuned length to provide an antenna that is well clear of the hull and spray ?
Or alternatively can the shielded portion be extended to give a longer total length but still with the original exposed wire on the end ?
Has any experimenting or research been done on this issue ?
Graham.:rockon2:

Boatman
05-24-2009, 10:06 PM
I would think mounting a antenna tube and capping it would be fine. the antenna on the fasst are "stiffer" than the old style so if you mount it under the antenna tube lets say, it would stand pretty much on its own. Orif you mount the rx next to the tube upside down just put some hatch tape across to keep it from falling out. Also yes, I have heard of problems with carbon hulls, but to honest I have heard of problems with abs hulls as well. Personally I have had no problems and I dont even run the antenna out of the hulls.

AntronX
05-25-2009, 12:37 AM
so my question is can this be extended in multiples of this tuned length to provide an antenna that is well clear of the hull and spray ?
Or alternatively can the shielded portion be extended to give a longer total length but still with the original exposed wire on the end ?

No, unshielded part cannot be extended in multiples. Making shielded part longer is fine, but would not be easy with this receiver. Just mount your receiver in a way so you can run this antenna through a hole and have the wire in a tube sticking out outside of your boat.

If you absolutely want to extend that antenna, you can cut off unshielded part and crimp the cable to reverse SMA connector, then buy small mobile WiFi antenna (http://cgi.ebay.com/Wi-Fi-WiFi-Booster-Antenna-for-Wireless-LAN-CARD-AP-SMA_W0QQitemZ400051713698QQcmdZViewItemQQptZLH_Def aultDomain_0?hash=item5d24f0b6a2&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A13 18|301%3A1|293%3A1|294%3A50) and glue it to outside of your boat anywhere on metallic or conductive surface to form good ground for that antenna.

EPower
05-25-2009, 04:34 AM
I am about to switch to Futaba FASST for all my boats but am a bit worried about the occasional report of radio problems due to the receiver antenna being masked by carbon fibre hulls or water spray from rooster tails etc.
I am aware that the antenna wire is shielded for most of its length so that in fact only the unshielded bit on the end is actually the antenna.
This exposed portion must be a tuned length, so my question is can this be extended in multiples of this tuned length to provide an antenna that is well clear of the hull and spray ?
Or alternatively can the shielded portion be extended to give a longer total length but still with the original exposed wire on the end ?
Has any experimenting or research been done on this issue ?
Graham.:rockon2:

Hi Graham as you know i have done all the wrong things with my Fasst radio never had the antenna out of the radio box always taped inside,in the lizard it's sitting next to my motor surrounded by carbon fiber,in the chaparral it's about 75 mm from the bottom of the v, never had a glitch in over two years of use i don't think anyone running Fasst at the club ever had any problems with it :smile:
Just go buy one don't play or change anything, and enjoy :beerchug:
Adrian

lomdel
05-25-2009, 04:58 AM
I also run my Futaba 3PM 2,4GHz Rx laying down inside my fibreglass hull and my range and response is fantastic. No glitches and no issues. Only thing with Futaba is you need to reverse the throttle channel, but that is easy to do.

G Doggett
05-25-2009, 06:08 AM
I've just ordered a 3PM 2.4GHz set from Tower Hobbies tonight.
I'm tired of waiting for the Kiwi dollar to improve.
Should see it in about 2 weeks.
Graham.:rockon2:

Fluid
05-25-2009, 11:39 AM
You will not be sorry. I've been racing a FASST for months and even in a high-powered carbon fiber hull it works great as far as I care to run, plus a bit.



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