How to choose a radio transmitter?

Krister · Post by **Krister** » 26 Oct 2005, 08:15

Hello
I have found out that there is a lot of differnt TX to choose from.
From what I understand, a computer radio is more useful then a regular. From what I understand is the 40MHz the most used frequency.
What type of modulation do you use? PPM, PCM or some other modulation?

What brand of TX do you use? To choose a radio that many other uses seems like a good way to go, at least it would be easier to make a decision. So tell me what kind of radio you all use thrugh out the world.

/Krister
SWE 68

awallin · Post by **awallin** » 26 Oct 2005, 08:39

Futaba 3VCS + Spektrum DSM Tx and Rx module.
Works on 2.4GHz, no crystals, as jitter free as PCM.
You need to be careful with the Rx antenna to get good range, see the RMG website for one option.

Prices for the 3VCS in europe are crazy, I got mine from hong-kong (www.rcmushroom.com).

I find that the most useful feature of a computer radio is 'exponentials'
i.e. the ability to tune the servo response vs. stick movement.
I have the rudder much less sensitive to stick movements in the centered position and the sheeting much less sensitive in the close-hauled position.

The spektrum Tx module draws quite little current, I consistently get 7 hours on the transmitter with 2-3 year old 1600 mAh NiMHs.

having said that there are guys in the A-heat at world and euro events that sail happily with cheap 27MHz AM systems (Attack-2 or similar).

Anders

Peter Allen · Post by **Peter Allen** » 26 Oct 2005, 14:28

HiTec Optic 6 Tx is available from Hobbyhorse.com in the USA for USD$170,this guy will supply it with the synthesized 75 Mhz module as a swap at no charge and an aftermarket Syn Rx gives all channels with a screwdriver and no crystals,i'm not shure about the availability of 40 Mhz.This radio is also compatible to the Spektrum DSM system.Regards Peter

ole_peder · Post by **ole_peder** » 26 Oct 2005, 18:41

Hi
Every radio basically works fine.
What to consider is what the rest in your club uses, we in NMS in Norway uses different radios but most Multiplex and Graupners. The advantage of having a radiosystem of the same brand as your buddy is that you can swap crystals when needed ie when travelling to a big race.

cfwahl · Post by **cfwahl** » 27 Oct 2005, 03:53

The transmitters I use are oldies now: Futaba Super 7s ( model FP-7U[AorG][ForP]S); but they happen to have just the sort of features that are mighty useful for yacht use, namely programmable exponential response on the throttle (winch) and aileron (rudder) channels, and also variable endpoint adjustment in the transmitter. You can find these on eBay occasionally -- I've even bought two of them in unused condition. I like eBay, because if you're judicious and patient, you can get a good deal.

Exponential means that you can set the servo to move in very small increments for a given stick movement around neutral (or at close-hauled for the winch), and much larger increments at the extremes of stick movement, with smooth transition of response in between. You'll laugh, but if you try a radio like this, I guarantee you'll like it a lot. There are now a lot of computer radios, but it seems that only the most expensive ones have exponential on the throttle channel. The "throttle curves" feature (used for helicopters) is almost as good. Glider radios are most likely to have exponential on throttle, because the soarers use that channel for a control surface.

There are other nice features that more expensive radios have: audible low battery warning, constant readout of how many minutes the unit has been on. They vary in how intuitive the programming menus are to use, but for someone who's determined, it's not difficult to learn any one.

I imagine that this new Futaba 3VC probably does the right things, since it's a high-end car radio. The modestly-priced JR 6-channel computer radio has throttle curves on it, aileron exponential, and it's nice-looking too. Many of the Asian-manufactured (Futaba, JR, Airtronics, Hitec) models, even the expensive ones, are product-design-challenged, in my opinion. The 3VC looks very nice in photos, but I haven't seen one in person, since it seems to be marketed only outside the USA presently. Multiplex EVO radios (now owned by Hitec) are the best looking (sleekest) ones I've seen, but they're out of my budget range; sort of like the SAAB!

I wouldn't buy a transmitter that doesn't have a removable RF (frequency) module: it just makes life easier. I don't much care about FM vs PCM (my transmitters will do either, as will most higher-end models), since I have never had interference using FM, but I always use a dual-conversion FM receiver. Hitec makes a nice small 3-channel one, the DCX.

Roy Thompson · Post by **Roy Thompson** » 03 Nov 2005, 23:53

I and others here use the Futaba T6EXA (40MHz). It can be programmed for up to 6 different models (I use 3 IOM rigs x 2 basic trims), it has exponentials and electronic trims and lots of other useful stuff. I got it from K-Bits in UK who supply it r/c sailboat ready. Price is quite resonable too.

Laurent Schock · Post by **Laurent Schock** » 04 Nov 2005, 10:04

Futaba FF6 also called 6XAS (40MHz), PPM and PCM, has all the gizmos...
one bad point, a bit "hungry" with batteries...but one day sailing is OK.

There's the newer model T6EXA even better!

ralph kelley · Post by **ralph kelley** » 19 Nov 2005, 16:57

My suggestion is to get the radio brand that everyone else in your area is using so that you can swap chystrals, battery packs etc. as needed at any one regatta.