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Model Forum / Radio Controlled / Air Models / July 2004Antenna too long
I understand not to cut my antenna, but the Rx I bought is a Hitceh Micro 555 five channel, It came with an antenna 41" long. The location where I want to install the Rx is under the wing of a fuse 36" long. This leaves the ant. sticking out the tail end about 20". This is way too long for my little airplane. I can just imagine the ant. flopping in the grass. I wonder if it's all right to have the antenna doubled back into the fuselage? Or maybe I should return it and get one with a shorter antenna? Wan The antenna length is important to the tuning of the rx. Since its a "little airplane", I would guess that you fly it close in. You can double up the antenna but leave as much space between the doubled up wire as possible. In other words, dont fold it back on itself. Double it in as big an "S" as you can. If you are flying it close in, the range loss shouldnt affect you but I would still range check!  SignatureDan AMA605992 KE6ERB http://www.fubar1.net "I've heard the screams of the vegetables..." Take out the "trash" to reply > I understand not to cut my antenna, but the Rx I bought is a Hitceh > Micro 555 five channel, It came with an antenna 41" long. The location [quoted text clipped - 9 lines] > > Wan Neither Tx nor Rx antennas in RC gear are "tuned". They are sized to get maximum signal strength for a nominal length that is kept reasonably short. I took a 3/8" square x 3/4" piece of balsa, rounded the edges, and wound about 15 turns of the antenna wire on it, about 6" from the Rx, so that I had about 14" left to go to the tail of my Crazy 8 electric. I flew that plane more than far enough away without any problem. BTW, the Rx was a GP electri-fly single convert with 30A esc built-in. David >The antenna length is important to the tuning of the rx. Since its a "little >airplane", I would guess that you fly it close in. You can double up the [quoted text clipped - 17 lines] >> >> Wan Well, that contradicts everything I was ever told. Go figure. Disregard my post. SignatureDan AMA605992 KE6ERB http://www.fubar1.net "I've heard the screams of the vegetables..." Take out the "trash" to reply > Neither Tx nor Rx antennas in RC gear are "tuned". They are sized to > get maximum signal strength for a nominal length that is kept [quoted text clipped - 29 lines] > >> > >> Wan >Well, that contradicts everything I was ever told. Not really. What he did was to create a base-loaded antenna. Base loads are EXCELLENT for receiving. IMO, he got lucky. The plane could as easily have crashed as flown well. "Don't fool with antenna length" is a good motto. Dr.1 Driver "There's a Hun in the sun!" Being a 'ham' for nearly 30 years provides one with lots of experience with antennas. The BEST antenna for ANY receiver frequencies well up into the VHF region ( 30-300Mhz) is the LONGEST piece of wire that can be strung up so that it does not get grounded. Hams regularly use 'long wire' antennas - 300, 400 , 500 feet long - even more! For a transmitter, the reason for tuning the antenna is to convert maximum RF power into radiated power. If the antenna is not tuned or matched, then power is reflected back (SWR measures this). If the RF final amp cannot handle the reflected power, it will eventually smoke. The transistors used in ~most~ RC transmitters can handle 100% of the power reflected back - think no antenna screwed in - and do it forever since the transistor can dissapate the RF energy as heat. And actually, I created a 'center loaded' antenna ! And it was not luck - center loading is commonly used to shorted even TX antennas with minimal signal strength loss. Check your range with the TX antenna removed - should be about 40'. Now wind your RX antenna up as I did and recheck range - I'll bet you cannot tell the difference. David >>Well, that contradicts everything I was ever told. > [quoted text clipped - 3 lines] >Dr.1 Driver >"There's a Hun in the sun!" > Neither Tx nor Rx antennas in RC gear are "tuned". They are sized to > get maximum signal strength for a nominal length that is kept > reasonably short. David, Interesting! I never gave it much thought, but you must be right. Given the frequency (and wavelength) of 72 MHz and 50 MHz Txmtrs, the antennae supplied are pretty pathetic. Do you know specifically about the compromises made by the industry to achieve reasonable performance while pushing the limits of good design standards? What do you think the SWR (or how far off resonance) is the Tx antenna? Obviously, the antenna would have to be trimmed within the limits of the final RF stage's ability to withstand the SWR, and at the same time radiate the required output for a reasonable range. I am sure the Rx antenna is less picky, given the expected distance from the Tx is only as far as we can see to fly the plane (not exactly DX). The coil you wound, is it based on any known design, or just a trial and error experience thing? I would be concerned about creating an RF choke. On a park flyer I could see that the reduced effectiveness of the Rx antenna would be less of a concern than on large model flying further away (unless an interfering signal comes along). Of course, on a large model the length of the antenna is not a problem to accommodate. It would be great to see a technical article on this subject in one of the R/C mags. Hmmm, I will have to write RC Report. Tom KA7TAM > Neither Tx nor Rx antennas in RC gear are "tuned". They are sized to > get maximum signal strength for a nominal length that is kept [quoted text clipped - 7 lines] > > David > > Neither Tx nor Rx antennas in RC gear are "tuned". They are sized > to [quoted text clipped - 46 lines] > > > > David David, I liked your idea. My plane is not a park flyer. It will be powered by an AXI 2212/34 motor. It's very fast and aerobatic. Lickety split, it could be 1,000 feet away. : ) If I made the balsa into a tube about 1" in diameter and 3 inches long, then wound the antenna in a spiral, wouldn't it be better? Thanks to the folks with their input, Wan My Crazy 8 is a Cobalt 400 powered screamer with a 31" span. I had it up high enough - about 5 mistakes worth since it was the maiden flight - to get that rascal trimmed. A couple of times I lost orientation with it until I remembered 'dark bottom - light top'. Never had any hint of range problem. 3/8" to 3/4" is more than enough diameter, and I 'tight wound' mine - which means the turns are touching each other. It's a BIG plane if you can SEE it well enough to control at 1000' ! David >I liked your idea. My plane is not a park flyer. It will be powered by >an AXI 2212/34 motor. It's very fast and aerobatic. Lickety split, it [quoted text clipped - 5 lines] >Thanks to the folks with their input, >Wan | Neither Tx nor Rx antennas in RC gear are "tuned". They are sized to | get maximum signal strength for a nominal length that is kept | reasonably short. I'm not sure that's quite true ... sure, they're not *carefully* tuned, but they do seem to at least aim for a 1/4 wavelength antenna, which would be the proper length to aim for. If you measure your 72 mHz receiver antennas, you'll find that just about all of them, except for the cheap single conversion receivers, are almost exactly one meter long, which corresponds almost exactly to a 1/4 wave antenna for 72 mHz. Now, I did measure some transmitter antennas (I removed the metal part and measured that, because some is hidden inside the unit.) These seemed to vary a lot more -- a JR radio was 1.16 m, Airtronics was 1.17 m, Futaba was 1.02 meters, and the Megatech transmitter was 0.97 m. A bit shorter than 1/4 wavelength I can understand -- there's a bit of wire inside the transmitter that will radiate as part of the antenna, but being longer than 1/4 wavelength suggests that they're just not being very careful. But even so, they're sort of close to 1/4 wavelength. I guess if they wanted much better performance, they'd go for exactly 1/4 wavelength at 72.5 mHz, and they'd include radials. You'd look like a dork with those radials, running the risk of poking somebody in the eye with them, but you'd have a nice strong signal :) (For receivers, they'd go for a full dipole rather than a half dipole whip antenna.But you'd also pick up more noise, so it may not help that much.) In any event, since current systems will let you control your plane much further away than you can see already, there's no real need to improve things. Also, the 50 mHz equipment uses antennas that are exactly the same lengths as that for 72 mHz. So either there's a loading coil in both TX and RX, or they're *really* letting things get sloppy. And for 27 mHz, again, similar antenna lengths, but there really must be a loading coil or it wouldn't work well at all. SignatureDoug McLaren, dougmc@frenzy.com Can anyone remember when the times were not hard, and money not scarce? > | Neither Tx nor Rx antennas in RC gear are "tuned". They are sized to > | get maximum signal strength for a nominal length that is kept [quoted text clipped - 8 lines] > are almost exactly one meter long, which corresponds almost exactly to > a 1/4 wave antenna for 72 mHz. And if you measure the 35Mhz ones that we use, they are also the same length. They TX antennae are fed via matching impedances that tune them broadly to the frequency in use. RX antennae - subject to random colocation with all sorts of other junk, are not nearly so critically tuned. In general they are loosely coupled - very loosely coupled - into a tuned front end stage that has a little effect, not much, in rejecting out of band signals and boosting the in-band. You can mess around with an RX antenna considerably with very little effect on either range or bandwidth. The same is NOT true of the transmitter. That is designed to operate at full extension and some distance away from metallic objects. > I guess if they wanted much better performance, they'd go for exactly > 1/4 wavelength at 72.5 mHz, and they'd include radials. You'd look [quoted text clipped - 4 lines] > whip antenna.But you'd also pick up more noise, so it may not help > that much.) Its worth building radials into models. One day I will test this out - wires running all over the structure... > In any event, since current systems will let you control your plane > much further away than you can see already, there's no real need to > improve things. Gets a little worse with cheap park flyer receivers. Here you may at best have little more than 500 yards. > Also, the 50 mHz equipment uses antennas that are exactly the same > lengths as that for 72 mHz. So either there's a loading coil in both > TX and RX, or they're *really* letting things get sloppy. They do, or its functional equivalent. Most TX antennae are fed through a tuned Pi filter, of which the impedance of the fully extended antenna forms a critical part. Most RX antennae are either taken to a turn on the input tuned circuit, or fed via a very small value capacitor to it. However the Q of this is very low. There is seldom any attempt to get the antenna to resonate - merely decoupling to make sure it doesn't affect the resonance of that coil too much. > And for 27 mHz, again, similar antenna lengths, but there really must > be a loading coil or it wouldn't work well at all. Yes. I built one years ago, and it was completely necessary to add a bottom loading col - that design did not use a PI filter. Another factor to consider when measuring antenna length for a particular frequency is the velocity factor of the wire. According to the egg heads electrons travel at the speed of light in a vacuum but slow down in other conductors. The velocity factor of most copper wire is .65. 2c worth > > | Neither Tx nor Rx antennas in RC gear are "tuned". They are sized to > > | get maximum signal strength for a nominal length that is kept [quoted text clipped - 63 lines] > Yes. I built one years ago, and it was completely necessary to add a > bottom loading col - that design did not use a PI filter. > I guess if they wanted much better performance, they'd go for exactly > 1/4 wavelength at 72.5 mHz, and they'd include radials. You'd look > like a dork with those radials, running the risk of poking somebody in > the eye with them, but you'd have a nice strong signal :) Taking into account the fact that the transmitter aerial is working against ground due to the reactance that your body imposes between tha transmitter and said ground, then adding radials would cock the thing up nicely. Radials are attached to an aerial which is going to be used at a suitable height and they will thus present the correct radiation resistance and the whole aerial system will work as planned. You wafting a transmitter around at a greater or lesser height above ground is not going to give a system which is of any use... it will almost certainly be worse than the currently used systems. > (For receivers, they'd go for a full dipole rather than a half dipole > whip antenna.But you'd also pick up more noise, so it may not help > that much.) Now thats an interesting concept.... if it was even remotely correct ! Dipoles are used in preference to end fed aerials because they do actually *reduce* noise. A dipole (suitably fed) is a balanced aerial and as such it greatly reduces impulse and other types of interference. Radio hams living in electrically noisy urban areas usually put up balanced aerial systems in order to be able to work effectively and hear low strength signals.... the dipole is still a very simple and effective balanced aerial. > In any event, since current systems will let you control your plane > much further away than you can see already, there's no real need to > improve things. > And for 27 mHz, again, similar antenna lengths, but there really must > be a loading coil or it wouldn't work well at all. Well at least you got this bit right... there really is a loading coil. I don't just want to single out your comments as being wrong. There are numerous other incorrect statements in this thread but I haven't time to pick them out and reply to each one so I am taking the easy option >:-) Reg > Neither Tx nor Rx antennas in RC gear are "tuned". TX antennae most certainly are quite highly tuned. RX antennae, in general, are not that highly tuned. > TX antennae most certainly are quite highly tuned. RX antennae, in > general, are not that highly tuned. How critical is placement of receiver antennae? I have a glider with carbon tube fuselage. I understand that placing the antennae inside would kill the reception. What about taping it to but outside the fuselage? I wasn't sure so I ran it outside and at an angle to the tip of horizontal stabilizer. How can I make it low drag and still have good reception? thanks, Michal Signatureu*x sys admin, programmer, aviation enthusiast, photographer > How critical is placement of receiver antennae? I have a glider with > carbon tube fuselage. I understand that placing the antennae inside > would kill the reception. I don't have a carbon fuse glider so can't comment from direct experience. I have seen many comments on this on a soaring mail group I subscribe to... mainly Americans. It would appear that there is considerable differences in the layup and weave of carbon fuselages. Some carbon fuses seem to present no problem with the aerial run inside. Other makes of fuse can cause severe problems and it is virtually essential to run the aerial outside of the fuse... sometimes aerials taped to the outside of the fuse give reduced range. One method that is sometimes successful is to run the aerial out inside a non-carbon wing and usually use a plug to connect it when the wing is fitted to the fuse. The comments I have quoted are from guys flying thermal, often at great height and range, and the last thing they want is reduced range on the radio gear. Unless you are competing, and every little then helps, how much drag do you think the aerial run outside and up to the top of the vertical fin is going to cause ? You could reduce the drag of an outside aerial by replacing it with smaller diameter enamelled smaller gauge copper wire... but it will not be as flexible. Try altering your receive aerial, but proceed with caution and make sure you are happy with range tests before you soar up and away in a thermal. Reg > What about taping it to but outside the fuselage? I wasn't sure so I ran > it outside and at an angle to the tip of horizontal stabilizer. [quoted text clipped - 3 lines] > thanks, > Michal The style antenna used in RC TXs is a verticle antenna. Verticles MUST have a GOOD ground plane of the proper size to be properly tuned - which RC TXs DO NOT HAVE and therefore CANNOT be 'highly' tuned. David >> Neither Tx nor Rx antennas in RC gear are "tuned". > >TX antennae most certainly are quite highly tuned. RX antennae, in >general, are not that highly tuned. > The style antenna used in RC TXs is a verticle antenna. Verticles > MUST have a GOOD ground plane of the proper size to be properly tuned > - which RC TXs DO NOT HAVE and therefore CANNOT be 'highly' tuned. Depnds on wht you man by 'highly' They are a lot more 'highly' tuned than RX. I know. Ive built both. > David > >>>Neither Tx nor Rx antennas in RC gear are "tuned". >> >>TX antennae most certainly are quite highly tuned. RX antennae, in >>general, are not that highly tuned. Those were YOUR words, not mine........... go back and read your post. David >> The style antenna used in RC TXs is a verticle antenna. Verticles >> MUST have a GOOD ground plane of the proper size to be properly tuned [quoted text clipped - 12 lines] >>>TX antennae most certainly are quite highly tuned. RX antennae, in >>>general, are not that highly tuned. > I understand not to cut my antenna, but the Rx I bought is a Hitceh > Micro 555 five channel, It came with an antenna 41" long. The location [quoted text clipped - 9 lines] > > Wan Basically yes, you lose some range, but there should still be more than enough: Indeed there are sound reasons why having an antenna all in one direction leads to nasty nulls in its polar response, and loss of signal with the model pointing right at the transmitter I was given a Hots II, 40 size, which is not very long. I drilled a hole in the bottom under the receiver, and dropped the antenna wire out the bottom. I held the end at the tail of the plan and pulled the slack towards the front of the plane. I ran the wire towards the front on one side and taped it to the bottom of the fuse (using yellow electrical tape), then across almost to the opposite side, then down to the back, taping the whole thing to the bottom.. it looks like a big fish hook.... I've had the plane almost out of sight on occasion, and never a problem. I have been flying it this way for 3 years. On my planes that had external antennas, now have them taped to the bottom to get rid of it sitting ugly on the top. On my new one, I may run an internal tube on my current build, or just tape it to the bottom... it is an easy fix and if for some reason the receiver has to be removed and replaced, easy job on the antenna wire. . Arne, USA (I finally caught up with 'The Joneses') . . > I was given a Hots II, 40 size, which is not very long. I drilled a hole in > the bottom under the receiver, and dropped the antenna wire out the bottom. [quoted text clipped - 14 lines] > Arne, USA (I finally caught up with 'The Joneses') > . Arne, you have an excellent idea. I think I may tape the over long antenna along the inside bottom of the fuse. This way it'll be out of sight and hopefully it will range check out OK. And if not, I can always do it differently. However, I do have a space problem, so I might loop the antenna a couple times along a foot long piece of light balsa (easier to install and extricate), and lay it on the inside bottom. This will leave about 17" loose remainng to be dealt with. Hmm.... Any possible problems with this? Wan Any antenna length will work -- until it runs out of range :-) I strongly suggest you fly as the manufacturer designed your radio -- the trailing antenna won't bother anything unless you step on it while taxiing, Cheers -- \__________Lyman Slack_________/ \______AMA6430 IMAA1564___/ \____Flying Gators R/C______/ \__Gainesville FL _________/ Visit my Web Site at: http://www.LymanSlack.com > I understand not to cut my antenna, but the Rx I bought is a Hitceh > Micro 555 five channel, It came with an antenna 41" long. The location [quoted text clipped - 9 lines] > > Wan Hey, they make a great 'foot brake.' > Any antenna length will work -- until it runs out of range :-) I strongly > suggest you fly as the manufacturer designed your radio -- the trailing [quoted text clipped - 19 lines] > > > > Wan On 6/22/2004 4:37 PM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge: Hayes makes a "base loaded" antenna that is 18" long. I have used this antenna on several scale models and have had no problems. The only thing I did notice with them is that doing a range test (motor running), I had about 10' - 15' LESS range than with the full length antenna. In regular flying, no problem. > I understand not to cut my antenna, but the Rx I bought is a Hitceh > Micro 555 five channel, It came with an antenna 41" long. The location [quoted text clipped - 9 lines] > > Wan > I understand not to cut my antenna, but the Rx I bought is a Hitceh > Micro 555 five channel, It came with an antenna 41" long. The location [quoted text clipped - 9 lines] > > Wan Wan, they make aftermarket "loaded" antennas that are only about 6". I've also heard wrapping the antenna around a large drinking straw works. Both methods reduce the range a bit. Since this is a small plane, it won't matter because the model will be out of sight before it is out of radio range. Morris Wan, There are a number of well engineered small antennas on the market. Check out Azzar's antennas at www.ecubedrc.com. They are super lightweight. Dean's makes a fine base loaded antenna that is also compact and lightweight. I use Azzar or Deans in all my planes. It is extra important that they be situated away from the motor, esc, batteries and servos. I have found that they have better range if situated upright - perpendicular to the fuse. Even a well engineered micro antenna will have about a 15% range loss compared to the stock antenna strung out in a straight line. But since you are flying a smaller model, you probably don't need the full 1 mile range anyway. Mike Wan <wanjung@toast.net> scribed in <7387603e.0406221237.568f1edf@posting.google.com>: > I wonder if it's all right to have the antenna doubled back into > the fuselage? Or maybe I should return it and get one with a > shorter antenna? never double them over rather cut it to half length if the plane is small, you won't be flying it so far away that it will go out of range anyway swarf, steam and wind -- David -:- the email address is real but not forever /"\ http://terrapin.ru.ac.za/~iwdf/welcome.html \ / ASCII Ribbon campaign against HTML E-Mail > - - - - - - -> X If you receive email saying "Send this to everyone you know," / \ PLEASE pretend you don't know me. > Wan <wanjung@toast.net> scribed in > <7387603e.0406221237.568f1edf@posting.google.com>: [quoted text clipped - 9 lines] > > swarf, steam and wind Never double them over? And cut it to half length? Here's a quote from Dr.1 Driver; <snip>"Not really. What he did was to create a base-loaded antenna. Base loads are EXCELLENT for receiving. IMO, he got lucky. The plane could as easily have crashed as flown well. "Don't fool with antenna length" is a good motto. Dr.1 Driver "<snip> I was really looking forward to the simple solution of doubling them as suggested by Arne earlier in this thread. But I will wind the antenna around a piece of light balsa, installing it inside the fuse as I had said before. I will of course do an exceptional range check just to be sure. By the way, someone I know said all 72 MHz radio Rx have 41" antennae. If true, why does one small GWS Rx have 19", another GWS Rx have 39" and my Hitech Micro 555 have 42"? Maybe we can fool with the antenna length of the receivers? Hmm... Wan Notice the range figures for that little GWS RX..... probably 300-500 feet. The range test is the 'proof of the pudding' as the old saw goes. David snip >By the way, someone I know said all 72 MHz radio Rx have 41" antennae. >If true, why does one small GWS Rx have 19", another GWS Rx have 39" [quoted text clipped - 4 lines] >Hmm... >Wan > Notice the range figures for that little GWS RX..... probably 300-500 > feet. That has more to do with the fact that its electrically rather 'basic' than the slightly shorter antenna length. In Europe on 35Mhz the JETI lightweight receivers come with very short antennae, and whilst not full range, are a lot better than the aveage GWS parkflyer. They are more expensive tho. > The range test is the 'proof of the pudding' as the old saw goes. > [quoted text clipped - 10 lines] >>Hmm... >>Wan > > Notice the range figures for that little GWS RX..... probably 300-500 > > feet. [quoted text clipped - 10 lines] > > > > snip TNP and David, David, by range figures, did you mean range test or range check while on the ground or in the air at 300 t0 500 feet? I had made a range test of the 72 MHz GWS Rx , 19'" antenna, ground level, Tx antenna collapsed at about 200 feet. I had been told 200 feet is enough? I will be flying that plane again today late afternoon. I will then do a range test at 300 feet or more and see how it turns out. But that little GWS Rx had been flown many times as far away as 1,000 feet, almost a quarter mile, no problems. I don't need to fly much farther than that with my little airplane though a mile would be like having a safety net, but I won't be able to see it. I'll let you know about today's range test..... Wan The newer GWS receivers have the shorter antenna. They have very good range. However, don't try that with a Hitec Feather! They have lousy range. > > > Notice the range figures for that little GWS RX..... probably 300-500 > > > feet. [quoted text clipped - 31 lines] > > Wan > The newer GWS receivers have the shorter antenna. They have very good range. > However, don't try that with a Hitec Feather! They have lousy range. The smallest GWS receivers also have lousy range, but the next size up are good on range. Not so good on rejecting other models especially close in. Fairly naff oscillators and mixers can easily respond to channels e.g. one half the IF frequency (225 Khz) away. And so on. These effects tend to happen 'close in' rather than at extreme range, as the receiver mixers overload and loads of harmonics get mixed up ... I tried to work out what a lousy front end would do in the presence of e.g. three or four transmitters all on different frequencies, all getting into the mixer, and basically it's anybody's guess. Suffice to say the more transmitters are on, and the closer in you fly to them, the more chance there is of something unpleasant happening de to specific combinations of them interacting. >>The Natural Philosopher <a@b.c> wrote in message > [quoted text clipped - 35 lines] >> >>Wan I have had far better luck with the tiny GWS receivers than the Hitec's. Granted neither are great, but probably get 1000 feet with the GWS and luck to get 500 with the Hitec. > > The newer GWS receivers have the shorter antenna. They have very good range. > > However, don't try that with a Hitec Feather! They have lousy range. [quoted text clipped - 54 lines] > >> > >>Wan >>>Notice the range figures for that little GWS RX..... probably 300-500 >>>feet. [quoted text clipped - 19 lines] > level, Tx antenna collapsed at about 200 feet. I had been told 200 > feet is enough? 200 feet is very good. I have successfully flown with no more than 30' ground range, though it was marginal. Normally with the model on a table or wall, I get about 100-200ft. I have paced out the limits I have flown (and crashed) to, so I know hopw far away I was..and surprsingly, even a 48" span model is seldo taken much further than aboyt 250yards. I reckon I have on occasion, gone twice that far with no sign of range loss. That is on the 60 yard ground test, so I reckon AT LEAST ten times the range wih TX extended as retracted. Which gives you at least 600 meters in the air. Probably a LOT more. > I will be flying that plane again today late afternoon. I will then do > a range test at 300 feet or more and see how it turns out. [quoted text clipped - 3 lines] > farther than that with my little airplane though a mile would be like > having a safety net, but I won't be able to see it. Yup. hat is not nconsistent with my findings either. > I'll let you know about today's range test..... > > Wan We had problems with adjacent frequency interference flying GWS single tuned rcvrs indoors. I cut the stock antenna in 1/2 per somebody's suggestion and have had no further interference problems. I have flown slow flyer models to at least 500 feet and 1/3 mile away with no apparent glitching from adjacent frequencies. Try it, if it gets worse, solder it back together. > >>>Notice the range figures for that little GWS RX..... probably 300-500 > >>>feet. [quoted text clipped - 48 lines] > > > > Wan The specs on the RX are what I was referring to. The EASIEST way to check range is REMOVE THE TRANSMITTER ANTENNA and check range. ~Normal~ RC receivers will yield about 40 feet of range when the antenna is stretched out. Saves a bunch of walking.... I do my range checks in my back yard which is 62 feet wide. David >> > Notice the range figures for that little GWS RX..... probably 300-500 >> > feet. [quoted text clipped - 31 lines] > >Wan It's not advisable to remove the transmitter antenna when it is turned on! > The specs on the RX are what I was referring to. > [quoted text clipped - 40 lines] > > > >Wan Old farts tale....... David >It's not advisable to remove the transmitter antenna when it is turned on! > Old farts tale....... > > David > > >It's not advisable to remove the transmitter antenna when it is turned on! That it's an "Old Fart's tale" is just another Young Whipper Snapper's Know-it-all fallacy. It depends on how much reflected power the particular TX's RF output stage can handle at the ambient temperature. Best to play it safe. Case in point, from Futaba's FAQ: (Old Farts need not read on) "When I am using my radio for programming, setup within my house, experimenting, etc, is there anything special I should do? You should ALWAYS extend your antenna at least the bottom or first segment when turning the radio on with a module in place. If left in the radio with the radio on at your work area with the antenna collapsed for more than short intervals, the module will be unnecessarily exposed and may shorten the life or even immediately damage the module/transmitter." Ye Olde Fahart Thank you fellow old fart! > > Old farts tale....... > > [quoted text clipped - 19 lines] > > Ye Olde Fahart > > Old farts tale....... > > [quoted text clipped - 19 lines] > > Ye Olde Fahart Hmm.... I came home one day and forgot to turn off the Tx. Left it on all night with the antenna down. After recharging, it seemed OK. But should I be concerned? Wan > > > Old farts tale....... > > > [quoted text clipped - 25 lines] > > Wan Over the years, I've done that more than once with a variety of transmitters. To date I have never noticed any lack of range or normal battery life. I do, however, run a full charge-discharge-recharge operation whenever I discover that I have done this, but there have been times when I have just charged up and gone flying with no apparent ill effects. I believe that it is possible to "burn out" some components in the output part of the transmitter circuitry. If this happens I assume the transmitter will cease to function - none of mine ever have. Malcolm. Malcolm >>Gregg Uhlendorf <greggu-REMOVETHIS-@garlic.com> wrote in message > [quoted text clipped - 47 lines] > part of the transmitter circuitry. If this happens I assume the transmitter > will cease to function - none of mine ever have. That's because the manufactires got tired of the warranty returns, and put a fatter transistor in the output stage. They now cost 50c mnore than they used to :-) > Malcolm. > > Malcolm >>>Old farts tale....... >>> [quoted text clipped - 23 lines] > all night with the antenna down. After recharging, it seemed OK. But > should I be concerned? Definitly. You have over murgled the woggle filter, and may encounter gremlins on your return.,..:-) > Wan > >>>Old farts tale....... > >>> [quoted text clipped - 26 lines] > Definitly. You have over murgled the woggle filter, and may encounter > gremlins on your return.,..:-) I can't help it, but how does one murgle a woggle? Definitely you're joking. I know of no woggles in our hobby : ) Wan >>Definitly. You have over murgled the woggle filter, and may encounter >>gremlins on your return.,..:-) > > I can't help it, but how does one murgle a woggle? Definitely you're > joking. I know of no woggles in our hobby : ) This is a Great Secret, known only to those who have inhaled enough NitroMethane to hallucinate Great Powers in the Sky. To understand this - and I may be struck off the Secret Brotherhood of Mysterious Flight for revealing even This Much, you need to read many Esoteric Technical Manuals, misunderstand Everything of a Scientific Nature, and Believe in Glossy Magazines. Then, My Son, when you have attained Oneness with the Ultimate in the Sky, and can Levitate effortlessly from the Flying Strip, you will be accepted as a Wise Guru. And Anything You Say will be Gospel. > Wan > > >>Definitly. You have over murgled the woggle filter, and may encounter [quoted text clipped - 14 lines] > Sky, and can Levitate effortlessly from the Flying Strip, you will be > accepted as a Wise Guru. And Anything You Say will be Gospel. O' Wise and All Knowing One. If I studied your ways that I had climbed the Mt. to seek. Would I, Icarus, then know the mysteries of flight and won't murgle my gurgles any more? For I have flown too close to the sun my father, and am positive I must have murgled them. I need to know your secrets so I may be as omnipotent as you? Seriously, my antenna checked out to over about a quarter mile in the air. That's about as far as I'd care to fly. Signed, Wan : ) >>>>Definitly. You have over murgled the woggle filter, and may encounter >>>>gremlins on your return.,..:-) [quoted text clipped - 24 lines] > Seriously, my antenna checked out to over about a quarter mile in the > air. That's about as far as I'd care to fly. Told you so, oh neophyte :-) > Signed, > Wan : ) > >>>>Definitly. You have over murgled the woggle filter, and may encounter > >>>>gremlins on your return.,..:-) [quoted text clipped - 26 lines] > > Told you so, oh neophyte :-) Hey, hey! hay! I looked up what murgle means. When split, MURG LE, we have MURG as an ACRONYM FINDER and LE short for LEFT EYE or LUPUS ERYTHEMATOSIS. Neat heh? Then everyone knows what gurgle means, for the neophyte of us; gurgle as in gurgling water or baby. Had to find out : ) Wan >>>>>>Definitly. You have over murgled the woggle filter, and may encounter >>>>>>gremlins on your return.,..:-) [quoted text clipped - 36 lines] > Had to find out : ) > Wan Now look up 'woggle' > >>>>>>Definitly. You have over murgled the woggle filter, and may encounter > >>>>>>gremlins on your return.,..:-) [quoted text clipped - 37 lines] > > Wan > Now look up 'woggle' Thought you had me stumped, didn't you? WOG GLE; WOG: Used as a disparaging term for a person of color GLE: in Acronym Finder Sorry about being off topic, but had to do it for the mirth. Wan >>>>>>>>Definitly. You have over murgled the woggle filter, and may encounter >>>>>>>>gremlins on your return.,..:-) [quoted text clipped - 49 lines] > > Wan http://myweb.ix.net.au/~wardb/ideas/woggle.htm#basics > >>>>>>>>Definitly. You have over murgled the woggle filter, and may encounter > >>>>>>>>gremlins on your return.,..:-) [quoted text clipped - 50 lines] > > Wan > http://myweb.ix.net.au/~wardb/ideas/woggle.htm#basics Bruce Ward, Your definition is better than mine. Could you let me have the site for the dictionary or thesaurus? It may have a definition for antenna. Might get one for insects though. Thanks, Wan > > >>>>>>>>Definitly. You have over murgled the woggle filter, and may encounter > > >>>>>>>>gremlins on your return.,..:-) [quoted text clipped - 59 lines] > Thanks, > Wan I am back to apologize to Mr. Ward. I went back and read again his article and realize he is the author. It was enlightening. Wan Hmm.... I came home one day and forgot to turn off the Tx. Left it on > > all night with the antenna down. After recharging, it seemed OK. But > > should I be concerned? I would, if the collapsed antenna caused a severe mismatch and overheated the output transistor . Hopefully they were designed to take a full load mismatch. If every transmitter that was inadvertently left on with the antenna collapsed self destructed Futaba, HiTec, JR, Airtronics etc. would be out of business. Or they would have the antenna enable a switch only when it was fully extended. Red S. > Hmm.... I came home one day and forgot to turn off the Tx. Left it on > > > all night with the antenna down. After recharging, it seemed OK. But [quoted text clipped - 3 lines] > overheated the output transistor . Hopefully they were designed to take > a full load mismatch. > If every transmitter that was inadvertently left on with the antenna > collapsed self destructed Futaba, HiTec, JR, Airtronics etc. would be out of [quoted text clipped - 10 lines] > > overheated the output transistor . Hopefully they were designed to take > > a full load mismatch. <snip>If every transmitter that was inadvertently left on with the antenna collapsed self destructed Futaba, HiTec, JR, Airtronics etc. would be out of business. Or they would have the antenna enable a switch only when it was fully extended. Red S. <snip> I think we've just about worn out this thread, but Jim, what Red said made a lot of sense. An antenna enabled switch, that would save a lot of anxiety. So we probably don't have to worry. Wan Lets get real, we are talking about a piddling little battery operated transmitter that would take a three years and four months to heat a cup of coffee! If the output transister used cost more than a packet of matches to make, then it should handle an open circuit load. If you un-hooked it from the 8 valve output stage, 10 kilowatt, radio transmitter that I used to repair back around the end of the 70's, then you could expect to see a few sparks....... Hope this helps, Peter From Peter: >Lets get real, we are talking about a >piddling little battery operated transmitter >that would take a three years and four >months to heat a cup of coffee! > >...the output transister.... should handle >an open circuit load. What is involved is not an 'open circuit load' but a severely _mismatched_ load, resulting in the output device having to eat a lot of reflected power that'd otherwise be going out the antenna. The result is a rise in current thru the output transistor. (remember how you used to have to 'dip' the current for resonance when tuning the finals in a broadcast xmitter?) In CB xmitters you can zorch the final in a heartbeat with a mismatched feedline. Thankfully, our little RC xmitters apparently have the sufficient overcurrent protection on the final to avoid disaster with the antenna down. I still wince every time I see it done, though. Bill (oc) An open or shorted antenna output is THE WORST SWR than can be achieved....... 100% reflected power. CB xmtrs have been idiot proofed since the late 1970's..... for preciously the reason someone else stated - people were bring back units with blown finals. You can leave the antenna disconnected or put a shorted UHF connector on the antenna jack and put a brick on the mike switch. As long as the 12v keeps coming, the final transistor will stay hot dissipating the heat generated! RC xmtrs are the same! David >From Peter: > [quoted text clipped - 19 lines] > I still wince every time I see it done, though. > Bill (oc) From David AMA40795 / KC5UH): >An open or shorted antenna output is >THE WORST SWR than can be [quoted text clipped - 4 lines] >reason someone else stated - people >were bring back units with blown finals. Yeah, the last I worked on CBs was in the 70s when people were blowing their finals faster than we could replace them. Apparently CBs have been idiot-proofed since then. I still wince out of habit though, every time I see someone run their RC xmittr with the antenna down. Even though knowing it's "safe", i never do it, just from the experience with the old CBs. Bill (oc) You'd run and hide when I do RC range checks...... I remove the antenna completely. Range should be about 40 ft....... saves my arthritis plagued body lots of walking. David >From David=A0AMA40795=A0/=A0KC5UH): > [quoted text clipped - 16 lines] > >Bill (oc) > You'd run and hide when I do RC range checks...... I remove the > antenna completely. Range should be about 40 ft....... saves my > arthritis plagued body lots of walking. Now that be creative. Jim ama353682/W1HRM (Age:67) I believe I meant I would be concerned if the antenna was not extended due to being shell shocked after having a RF choke blow like a grenade while running 1000 watts and not matched. You usually dont learn anything the second time you are kicked by a mule. "Col. Sherman T. Potter. > > You'd run and hide when I do RC range checks...... I remove the > > antenna completely. Range should be about 40 ft....... saves my [quoted text clipped - 7 lines] > while running 1000 watts and not matched. You usually dont learn > anything the second time you are kicked by a mule. "Col. Sherman T. Potter. I am having enough trouble trying to log in here already. Not really complaining, though I had to enter my ID and password twice. Anyone know an easier way? But Jim, Red was proposing an automatic switch when the antenna is to be raised. However, I agree with you about too many gizmos to complicate our hobby. You are the one who is being creative. "Col. Sherman", "shell shocked" and all. Wan No way Jose(Wan). I dont want yet another switch to worry about. Especially in the antenna circuit. I have trouble keeping the darn nut tight on the bottom of it, i check it regularly. Old rig. > I think we've just about worn out this thread, but Jim, what Red said > made a lot of sense. An antenna enabled switch, that would save a lot > of anxiety. So we probably don't have to worry. > > Wan The GWS can have quite a long range. It is a single conversion receiver and the further away you get, you are more susceptible to hits. Depends on how quite you're flying area is... PCPhill > Notice the range figures for that little GWS RX..... probably 300-500 > feet. [quoted text clipped - 12 lines] > >Hmm... > >Wan |
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