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Model Forum / Radio Controlled / Helicopters / December 2004Transmitter Range
Hi Using a Sanwa RD-8000 Transmitter with the antenna fully opened working with the Original Sanwa receiver 72 Mhz is about 100 meters (on the ground) before I get some small vibrations in the Heli rudder servo. With the antenna closed I get about 15 meters before I notice the servos going out of control, I compared with another Transmitter - RD-6000, and got the same results on the ground. In the air it is working Ok for ranges more then 100 meters. My Futaba 9ch (50 Mhz) with a closed antenna works Ok up to 30 meters on the ground. Are these typical numbers? Thanks > Hi > [quoted text clipped - 13 lines] > > Are these typical numbers? The Sanwa sounds suspect to me. I'd expect a good 100 yards/metres with the twig collapsed so long as the heli is about 3ft off the ground (a helper holding it, or sitting it on a table etc) .  SignatureBeav Please note my E-mail address is "beavis dot original at ntlworld dot com" (with the obvious changes) Beavisland now lives at www.beavisoriginal.co.uk > The Sanwa sounds suspect to me. I'd expect a good 100 yards/metres with > the twig collapsed so long as the heli is about 3ft off the ground (a > helper holding it, or sitting it on a table etc) Hate to be the helper if it's on :) Most of the radios that I've worked with (I have a couple of 9Z's an work with a bunch of 9C's and some JR's at our club field) work wel beyond 50m with one segment extended. With the antenna fully extende they work so far away that you can't see the helicopter on the benc (maybe 250m or more). The 9Z needs to have the large segment extende to have ANY antenna and the 9C seems to be the same. That's no usually the case with the plastic cased transmitters though. The way I range check is to leave the transmitter sitting on the tabl with one segment extended (the big one), and carry the helicopter away If its a PPM system I look for a jittery servo (usually AIL, but coul be anything). If its a PCM system I look for failsafe (set throttle t fail-safe at idle and then leave the transmitter stick at full). If see the jitter or failsafe before 50m its invariably a receiver antenn problem or a low battery. Usually I can get more than 100m away wit PPM and 150m with PCM. When you find the twitch, stop and slowly rotate the helicopter throug 360 degrees to see if one orientation is worse than the others. The with the heli in the worst orientation, walk back toward th transmitter until the jitter stops or the fail-safe condition goe away. You'll find that the pattern is irregular and usually "hear shaped" with sometimes large nulls in the pattern. It's worse if yo have your antenna wrapped around something metal or carbon. Well.... you asked ;) ..paul heliham at bigfoot dot co -- phscot >Most of the radios that I've worked with (I have a couple of 9Z's and >work with a bunch of 9C's and some JR's at our club field) work well [quoted text clipped - 26 lines] > >heliham at bigfoot dot com Range checking is done with the aerial down. The heli should also be placed in an open area i.e. away from metal roofs, fences, etc. As for ranges yes it will vary based upon make/model. The Tx power can vary from 300mW to 1W max as well as the Rx sensitivity so you certainly will see different range figures. You do a range check with what you have and note the distance you then use this for reference. Range checks are always performed before commencement of the flying session, alteration to Rx aerial layout, changing to different type of Rx aerial, etc. Any drop in range from the normal requires investigation. I actually have a 4 channel old Sanwa airplane radio (non computer) and I get a range of about 20m never had a problem. Others with the same model of radio also got similar range. These days though I mainly use the computer radios which are Hitec and JR. The JR radio gives the greatest range of about 50m. BTW how is the aerial routed on theheli? Reckless Loony More reckless and loonier than ever Muhahaha !! >Hi > [quoted text clipped - 15 lines] > >Thanks Range checking is done with the aerial down. The heli should also be placed in an open area i.e. away from metal roofs, fences, etc. As for ranges yes it will vary based upon make/model. The Tx power can vary from 300mW to 1W max as well as the Rx sensitivity so you certainly will see different range figures. You do a range check with what you have and note the distance you then use this for reference. Range checks are always performed before commencement of the flying session, alteration to Rx aerial layout, changing to different type of Rx aerial, etc. Any drop in range from the normal requires investigation. I actually have a 4 channel old Sanwa airplane radio (non computer) and I get a range of about 20m never had a problem. Others with the same model of radio also got similar range. These days though I mainly use the computer radios which are Hitec and JR. The JR radio gives the greatest range of about 50m. BTW how is the aerial routed on theheli? Reckless Loony More reckless and loonier than ever Muhahaha !! Reckless, I agree that the aerial is DOWN, but for the 9Z at least and some o the other newer radios, DOWN="ONE-segment-extended" (It says so in the manual :) ). The metalized case offers some kind of shielding an because of the way the antenna is connected, it can cause the transmitte module to overheat if it's "ALL the way down". On the top-end JR radios an the newest Futaba radio, the antenna must be removed from its storage compartment and attached. One segment is as far down as it can be an still be attached. On the older plastic cased radios (all the 4 through 7 channel radio and most the 8 channel ones I've ever seen), DOWN="All the way down", becaus the "one-segment" is extended "inside the radio". I also agree that the range number doesn't mean much except for th first time. After that, its the change from "normal" that counts. If th antenna is wrapped around the tail brace or the landing gear or worse yet coiled up inside the canopy, then the range will be "short". Regards, ..pau -- phscot >I agree that the aerial is DOWN, but for the 9Z at least and some of >the >other newer radios, DOWN="ONE-segment-extended" (It says so in the >manual :) ). Correct. >The metalized case offers some kind of shielding and >because >of the way the antenna is connected, it can cause the transmitter >module >to overheat if it's "ALL the way down". If you run the aerial shorter than fully extended with ANY radio you will get the RF module to run hotter simply because the aerial impedance is now mismatched to the output impedance of the RF amp in the module thereby you no longer have a condition of max power transfer and hence the RF power amp Transistor will run hotter than it normally would. In the case if the 9Z Futaba do not give any warning in the manual with regards to damage so it along with other radios is capable of dissipating the extra heat produced as a result of the impedance mismatch. If you don't have the one segment extended with the 9Z and do a range check you will find that the range will be significantly less than what is specified in the manual (min 30 paces) and would be significantly less compared to other Futaba radio models which the user maybe accustomed to hence the one segment extended is to provide for a more accustomed range check distance. This is not a disagreement but merely an explanation as to why is it so. Reckless Loony More reckless and loonier than ever Muhahaha ! Ah...Er..... I write only of the 9Z. The requiement is to extend the ENTIRE antenna out of the case, but only one segment high. The reason is that the antenna is actually disconnected until the outermost segment is pulled into the flex ball at the top of the transmitter case. With this arrangement you should actually get a range check longer than most other transmitters where you keep the antenna totally collapsed. As I recollect, the Madera racing preflight requirements had the 9Z getting at least 50 feet with antenna out, only one segment high, with the engine running. With ALL transmitters, IMO, the most important thing not yet mentioned is to do a range check before the first flight of a new/changed installation, and on a VERY REGULAR basis thereafter. The check should encompass a 180 degree arc, from wing tip to wing tip. This will allow you to readily identify a CHANGE in ground range. When a change is noted, then an investigation and repair is in order. As with others; not a disagreement but an amplification. Most everything written in this thead thusfar is mostly correct. >>I agree that the aerial is DOWN, but for the 9Z at least and some of >>the [quoted text clipped - 31 lines] > Reckless Loony > More reckless and loonier than ever Muhahaha ! |
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