Whats the difference between low band and high band on a reciever? I have a futaba 6EXA radio, So lets say I get another plane I know I would have to get another flight pack but would I have to get another crystal? I'm confused.

Yes, you will probably need to buy the crystal seperately. High/low refers to your chanel:
for example, 23 is low, 46 is high. Buy the correct one for your frequency

so 26 and under is low and anything over 26 is high? Sorry I am not clear with what you mean.

The dividing point between the so called hi and lo band is ch35. First this applies only to Futaba Rx's all the other brands do not have this restriction. Unless you have a Tx with a removable RF module then you cannot change the channel (crystal) yourself without a retuning. However you can legally change the crystal for another channel in your Rx legally. So what Futaba is saying if your Rx was originally on a channel below #35 then you should only change that Rx to another channel that is also below #35 unless you send it in for retunning.

John

Low Band (Ch. 11-35)
High Band (Ch. 36-60)

Okay so if my TX crystal is on 72 MHz band, I dont have to keep buying new crystals for the TX but I just have to buy new crystals only for the new reciver but I have to make sure its on 72MHz correct?

For example all i would buy for a new plane is a flight pack with a crystal like this(my reciever is low band)
http://www2.towerhobbies.com/cgi-bin...I=LXBFK7**&P=M


How would I know what number that receiver crystal is? for example 12.
I wont need 2 crystals one for TX one for RX but only for Rx (Reciever)

so all i have to keep buying for new planes is crystals only for the reciever never for the transmitter unless I descide to use a different frequency and band.

72mhz is the spectrum of all the freq's between 11 and 60.

Here is a [link=http://www.futabarc.com/faq/frequency.html]frequency chart [/link] that might help explain it better for you.

Unless you have a radio with a fequency module, it is against the FCC regulations to change the transmitter crystal.

If your on channel 12, you just buy crystals for all your receivers for channel 12.

okay so I dont have to keep buying new crystals for the TX but I just have to buy new crystals only for the new reciver and just make sure they are all on the same channel? I just want to make sure.

You got it. When you order a reciever just order it with a crystal that matches the channel on your transmitter. If its in the low band, order a low band reciever and channel 12 crystal and you'd be good to go, it will work with your existing tx.

Not to really confuse you but hitech flight packs also work with futaba transmitters and do not suffer from Hi or low band problems. Depending on the reciever you buy they will work with the servos of whoevers you have. If you order from tower they can help steer you in the proper direction when you are buying the reciever or flight pack if you let them know you need a little help.

There are a lot of trade offs when designing a receiver. In general, it is a good idea to limit the bandwidth at the front-end. Typically, with less bandwidth you can put more gain at the beginning of the receiver and reduce the noise floor. I'm just guessing that you will get a little better performance on the Futaba receivers when you are at the very limits of the range. The fact that the FCC mandates 50 interfering signals 20 kHz apart (The other transmitters at your field) complicates the normal noise issues.

Apparently, Futaba engineers decided it was better to divide the 72 MHz band into two parts. If you use a low band receiver with a high band crystal, the receiver will not have the designed total gain. It will work on the bench, but you risk losing it when the plane is a 1/2 mile away. If you happen to take-off with your transmitter antenna in the retracted position, you may lose it right at the end of the runway.

I know a lot of people use the Hitec receivers in Combat events. It seems a combat event, with lots of people flying simultaneously, is a nice real-world test of receiver noise rejection. So I'm not convince the Futaba approach is worth the hassle of only being able to use half the alloted 72MHz frequencies with any given receiver.

Carl

Carl,
Some good points, and I've never seen any problems with any brand of receiver.

I will say however, that I've heard of people losing their planes becasue they took off with the Tx antenna collapsed. I have flown twice now with a collapsed antenna with my Futaba equipment. The first time I flew 2 or 3 full circuits of the field at probably 75 to 100 feet altitude before I realized it. Second time was less dramatic, but my point is, I still had control of the planes.

It may have been as much my choice of Rx antenna routing (to the vertical stab), but....
Dennis-

Haha... I have a couple of hand launched SPADs, and I can't you how many times I've walked out onto the field with my TX in one hand, and my plane in the other hand with the engine running, only to realize my TX antenna was down.... DOH! Have to go back to the starting bench, set the plane down on it's stand, extend the antenna, and try again. Luckily the only times I've actually flown with a collapsed antenna, it was at least out about 1/3 to 1/2 of the way!

well i'm having trouble detecting what channel my reciever is. When I bought the 6EXA it came with BIG STICKERS of the number 36. So is the channel on 36? so that would be High band. I dont want to take out the RX and find out cause I have it foam rapped and them tied it really good inside the plane. how can I tell? There is also a sticker on the back of my Tx that sais 36.

If your Rx is ch 36 which is 72.51 Mhz, then your Rx is hi band.

If you bought the radio new and have not diddled with the crystals then you can be assured it is a high band. If you bought it used there is always the possibility that someone had diddled with the crystals. Assuming that the Rx functions with the Tx you can confirm the ch by popping the crystal and holder out from the back of the Tx and read the Frequency right on the crystal or it is usually on the holder as well, reinstall it. It cannot be put in backwards there is no polarity with crystals.

John

I have learned.... NEVER TRUST THE STICKERS!!!!!

on the 6EXA, you can pull the TX crystal out, and check the ... ahem... sticker on the crystal

let me rephrase... I never trust the stickers on the outside of a TX/RX.

To only know for sure, physically look at the sticker on the actual crystal.

thanks guys it is in fact 36. I'm looking for the number 36 on the crystal I dident know that 36 = 72.510. Thanks again