futaba 9cas..synthesized or not? - RC Groups
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Dec 24, 2005, 02:44 PM
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Severed1's Avatar

futaba 9cas..synthesized or not?

hey again people! iv'e pretty much got my heart set on a futaba 9c series ...i was looking on servocity.com and they seem to have the best deal that i can find.. but what is the diff between one with a synthesized module and one without? the diff is abot 50$ between the two ..advantage or not?also off topic (Sorry bout that), is www.servocity.com a reliable place to purchase from?
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Dec 24, 2005, 04:02 PM
Registered User
A TX with synth module doesn't need a crystal and is therefore not limited to operating with just one channel. The synth module usually has a way for you to select what frequency to use - they are great when you fly at organized events or when you travel to other flying sites where you can't anticipate what channels are being used. Most folks carry a few different Rx crystals with them to use with their fav channels. Or you can spend money and get a synth Rx.

I've had great service from servocity.

Dec 24, 2005, 04:07 PM
Registered User
I have a 9C and use both the synth module and a regular module.

If you typically only fly on one channel then it is not worth the extra $. If you like to use many channels then it is priceless.

I prefer to use one frequency for all my planes. A good friend prefers to have each plane on a different channel so he is always able to fly something without waiting for a specific frequency.

The synth module will also use a little more power so your Tx battery has to be charged alittle more often. You also need to be in the habit of checking what channel a synth module is on prior to turning it on each time if you change channels frequently.
Dec 24, 2005, 06:09 PM
Registered User
Severed1's Avatar
is the synth module something that can be installed later on or would i need to buy the radio with it in it already.. the synth would be nice to not have to buy crystals for all of your recievers, but then again having all planes /choppers on the same channel is a litle more convienient
Dec 24, 2005, 06:31 PM
unRegistered heli abUser
Frequency modules plug into the back of the transmitter. A transmitter without a module plugged in is useful with a simulator or as a student's Tx. The module is either fixed to a single frequency (selected at time of purchase), or is able to synthesize any legal frequency. The modules are easily swappable.

So if you buy a single frequency module now (to match all your receivers), you may later sell it and replace it with the synth module (to use with multiple receivers, each on it's own frequency, or to use on any channel with a synth. receiver).
Dec 25, 2005, 01:43 AM
Registered User
I like the synth module for the 9z because the frequency selection is done in the radio menus. The synth module for the 9c has dial on the back that you have to turn with a small screwdriver - this is much less convenient, so certainly something to consider. Given that, I haven't actually used this device myself - can someone make a comment on that; do you find it annoying to change frequencies with the 9C synth?

Right now I run everything on one of two channels, and I have two frequency modules, so I can swap them out quickly and easily. This kind of happened incidentally when I bought my second radio, but it worked out nicely.

I'm not sure how they justify a $50 cost increase, since the standard modules are $50 and the synth is $90...

Dec 25, 2005, 02:32 PM
Registered User
Severed1's Avatar
cool thanks for the info !!! i cant tell everyone how much of a big help they are!!!! this forum is definately worht it!!!!!
Just thought of this.. is the 9c radio compatible with all receivers as long as they are negative shift? hitec micro receivers are my chioce.. and can someone give me a quick idea of what negative and positive shift is.. and dual and singly conversion ?.. thanks again!!!
Dec 25, 2005, 04:23 PM
Multi-Platform Pilot
barracudahockey's Avatar
Any negative shift rx on the correct channel (or any channel if you get a synth module) will work with the 9c with the exception of some older futaba pcm 512 recievers. Picture a 5 volt dc signal that is interupted to 0 volts, those "spaces" or interupptions are the data, that would be an example of negative shift as opposed to a 0 volt signal with 5 volt spikes representing the information, that would be positive shift. Its not biggie, as long as the rx is negative shift it will work, I use a mix of futaba and hitec.

Single and dual conversion are just the way the reciever handles the incoming signal, dual conversion has better noise rejection but some excellent JR recievers are single conversion so "better" isn't always the case.
Dec 25, 2005, 04:37 PM
Registered User
Yep, Futaba Tx's and Rx's are all negative shift in the US. Pos and neg shift Tx outputs are just inverted versions of each other, but its not possible to use a pos shift Tx with a neg shift Rx, and vice-versa. In the US, some Tx's are pos shift only (JR, some Airtronics models), some are neg shift only (Futaba, some Hitec models), and some can support both (some Hitec models, some Airtronics, some Multiplex). In most other countries, pos shift only is used, even if its Futaba or Hitec, so the US is the one market where you have to worry about all this silliness! I've read Futaba is partly to blame for introducing neg shift to the US in an attempt to differentiate themselves from other brands

I made a decision to not purchase any fixed-shift Rx's. Instead, I buy only auto-shift Rx's that can support both pos and neg shift. This way, your investment in Rx's will last into the future even if you decide to switch Tx brands and shift later on. In other words, you won't be forced to stick with a certain brand/shift in the future when you want to buy a new Tx. There are lots of good autoshift/dual-shift Rx's out there - Berg/CC, Sombra, Hitec (some new autoshift models are just coming out), and others. I believe even JR makes one.

SC vs DC is pretty much a dead issue these days. And many of the SC Rx's use a DSP to augment analog filtering (Berg/CC, Sombra, JR, Multiplex, etc.) so they are just as good, if not better, than DC Rx's. The only Rx's I'm aware of where you need to be careful are the low-cost non-DSP SC Rx's targeted towards parkflying - the Hitec Feather is an example. These Rx's are designed to be used only for close-in flying and don't have the range of the full-range Rx's.

Myself, I use a JR9303 (Pos shift) and an old Hitec Flash5x (Neg shift). All my Rx's are Berg autoshift. The new Berg Rx's being made by Castle Creations are especially attractive due to their small size, features, and cost. Only the new 4ch's are out, the new 7ch is forthcoming. The new Hitec autoshifts and FMA look promising too but don't know if they'll win on price. Others will chime in with their favorties.

HTH & happy holidays!


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