What to do w/ 72mhz?
02-22-2014, 04:36 AM
#26
Senior Member
I know what you mean. I have five or six 72MHZ radios I haven't used in years. I just can't seem to part with them because of all the money invested over the years. I would still be using them, but, I transitioned to 2.4 because most of my airplanes now have gas engines. The ignitions throw out a lot of RF "noise" that 2.4GHZ seems to be more immune to.
I almost lost my first gasser using a 72MHZ radio. I had two problems on my maiden flight. The throttle servo failed at the full position so I couldn't land until I ran out of gas. The bigger problem was every time the airplane was at one end of the field, it would go "wild" from radio glitching, but I managed to save it each time, just before it hit the ground. I did a radio ground range test prior to flying, but not with the engine running (big mistake). Range testing after that flight, I could only get about 10 paces from the airplane before the servos went wild when the engine was at full throttle. I then changed over to 2.4GHZ and have never had any more "glitching" problems (but I still range test at full throttle, just in case).
I almost lost my first gasser using a 72MHZ radio. I had two problems on my maiden flight. The throttle servo failed at the full position so I couldn't land until I ran out of gas. The bigger problem was every time the airplane was at one end of the field, it would go "wild" from radio glitching, but I managed to save it each time, just before it hit the ground. I did a radio ground range test prior to flying, but not with the engine running (big mistake). Range testing after that flight, I could only get about 10 paces from the airplane before the servos went wild when the engine was at full throttle. I then changed over to 2.4GHZ and have never had any more "glitching" problems (but I still range test at full throttle, just in case).
02-22-2014, 04:45 AM
#27
I know what you mean. I have five or six 72MHZ radios I haven't used in years. I just can't seem to part with them because of all the money invested over the years. I would still be using them, but, I transitioned to 2.4 because most of my airplanes now have gas engines. The ignitions throw out a lot of RF "noise" that 2.4GHZ seems to be more immune to.
I almost lost my first gasser using a 72MHZ radio. I had two problems on my maiden flight. The throttle servo failed at the full position so I couldn't land until I ran out of gas. The bigger problem was every time the airplane was at one end of the field, it would go "wild" from radio glitching, but I managed to save it each time, just before it hit the ground. I did a radio ground range test prior to flying, but not with the engine running (big mistake). Range testing after that flight, I could only get about 10 paces from the airplane before the servos went wild when the engine was at full throttle. I then changed over to 2.4GHZ and have never had any more "glitching" problems (but I still range test at full throttle, just in case).
I almost lost my first gasser using a 72MHZ radio. I had two problems on my maiden flight. The throttle servo failed at the full position so I couldn't land until I ran out of gas. The bigger problem was every time the airplane was at one end of the field, it would go "wild" from radio glitching, but I managed to save it each time, just before it hit the ground. I did a radio ground range test prior to flying, but not with the engine running (big mistake). Range testing after that flight, I could only get about 10 paces from the airplane before the servos went wild when the engine was at full throttle. I then changed over to 2.4GHZ and have never had any more "glitching" problems (but I still range test at full throttle, just in case).
02-22-2014, 05:30 AM
#28
Setup definitely played a roll and It was a combination of issues. The "electronic" Melody ignition was notorious for throwing out a lot of RFI (I had read one post where the comment was "Melody ignitions could shoot down a full size aircraft"). I replaced it with a RCExel ignition. And yes, by re-arranging components, I could get a successful range check with the engine running using my 72MHZ radio. I continued to fly a few times with the 72MHZ radio and still had some unexplained glitches. By now, my confidence was shaken, so I switched over to 2.4GHZ, and have not had any issues since.
02-22-2014, 07:35 AM
#29
Senior Member
All of my Saito engines are converted to CDI W/glow fuel.
I flew that combination way back in the late '90s.
Some of the precautions I took in addition to the grounded shield plug lead that is standard on CH Electronic CDI were:
Keeping the Rx as far from the actual ignition components as pracical
Always using a non metalic pushrod for throttle such as Sullivan "Goldenrod".
Never installing the Rx in close proximity to any metal pushrods.
On the old metal cased modules, using an auxiliary ground from the engine block to the module case.
I never had a radio failure. (as long as I didn't range check in flight)
I flew that combination way back in the late '90s.
Some of the precautions I took in addition to the grounded shield plug lead that is standard on CH Electronic CDI were:
Keeping the Rx as far from the actual ignition components as pracical
Always using a non metalic pushrod for throttle such as Sullivan "Goldenrod".
Never installing the Rx in close proximity to any metal pushrods.
On the old metal cased modules, using an auxiliary ground from the engine block to the module case.
I never had a radio failure. (as long as I didn't range check in flight)
02-22-2014, 05:46 PM
#34
Senior Member
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Gassers on 72mhz PCM work fine until the CDI systems fails. I have been there and done that. Replaced the CDI and problem solved but I stopped using gas engines. Word to the wise is never use a FM receiver for anything other than gliders. I test flew a H9 PA18 today on 72mhz with a PCM receiver and flew it out to a measured distance of 3000' ft with no problems. For all those who are advocates of 2.4 kHz talk to those who have lost their airframes while flying this technology. The new technology has not only helped the manufactures save money but has also taken the responsibility away from the modeler.
02-22-2014, 07:07 PM
#35
Pm sent
02-22-2014, 07:20 PM
#36
My Feedback: (2)
72 MHz is actually a better frequency than 2.4 GHz for communications using omni-directional antennas. However, spread spectrum is better than FM or PCM. The best system would be spread spectrum on 72 MHz, but that will never happen because of the bandwidth required and other frequency allocations on 72.
Anyway, nothing wrong with 72 MHz FM or PCM as long as no one else is on your frequency. In fact it even has some advantages over 2.4.
Higher end 72 MHz computer radios still sell used for good prices.
Anyway, nothing wrong with 72 MHz FM or PCM as long as no one else is on your frequency. In fact it even has some advantages over 2.4.
Higher end 72 MHz computer radios still sell used for good prices.
02-22-2014, 09:31 PM
#37
Moderator
2.4ghz eliminated the most commonly encountered problems in RC- radio interference caused by stray signals, transmitter conflicts, gas ignitions, and vibrating metal on metal connections. True, it doesn't penetrate as well as 72mhz and never will because of simple physics. But it penetrates well enough for our purposes.
To my mind the old radios aren't worthless because they are 72mhz. They are worthless because of features. JPMacG made a good point that high end 72mhz radios are still somewhat valuable, but even they are hard to compare favorably to the 10-12 channel radios being currently produced. And when you add to that the years that are on these old radios that do take their toll on pots and solder joints, it's hard to make a case to keep using them.
To my mind the old radios aren't worthless because they are 72mhz. They are worthless because of features. JPMacG made a good point that high end 72mhz radios are still somewhat valuable, but even they are hard to compare favorably to the 10-12 channel radios being currently produced. And when you add to that the years that are on these old radios that do take their toll on pots and solder joints, it's hard to make a case to keep using them.
02-22-2014, 10:59 PM
#38
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I stopped flying in 2001 and just got back in 2013. I feel like I traveled back to the future, lol
Got a spektrum DX7s and it's bullet proof and not to mention the telemetry is really awesome, rx battery voltage, ignition voltage, engine temp, RPM, and flight log. Now I'm going to get a G force sensor just for s.... and giggles.
Got a spektrum DX7s and it's bullet proof and not to mention the telemetry is really awesome, rx battery voltage, ignition voltage, engine temp, RPM, and flight log. Now I'm going to get a G force sensor just for s.... and giggles.
Last edited by dlinares126; 02-22-2014 at 11:02 PM.
02-23-2014, 03:07 AM
#39
I learned on 72mhz and still use them today. I bought a 2.4 2 years ago, but its never left my shop. Guess I'm not comfortable with it yet. To me, its a matter of how much I trust my radio to do what I want.
02-23-2014, 08:23 AM
#41
I have no intention of getting rid of my 72 mhz stuff...some of the transmitters just fit in my hands so nicely, that they feel comfortable, and well balanced, unlike some of the stubby antenna's 2.4 tx.'s
I have a lot of it...(72mhz stuff)...and several newer radios on 2.4 as well...
Used to be when I'd go to the field, I would have to share the freq. board pin with someone else...now I can go out, and since most guys are using 2.4 I typically can have the freq. pin all day, if I want it...
One thing you need to remember though, if you get used to using radios on 2.4 and then switch to a plane w/ a 72mhz radio, is that you gotta remember to pull out the antenna!
A friend has an old 10X that has about 6 or 8" of antenna that doesn't collapse into the case...and he flew an entire flight w/o extending the antenna...kind of embarrasing, but luckily there were no problems. (good ad for an old JR radio, I guess)
I have a lot of it...(72mhz stuff)...and several newer radios on 2.4 as well...
Used to be when I'd go to the field, I would have to share the freq. board pin with someone else...now I can go out, and since most guys are using 2.4 I typically can have the freq. pin all day, if I want it...
One thing you need to remember though, if you get used to using radios on 2.4 and then switch to a plane w/ a 72mhz radio, is that you gotta remember to pull out the antenna!
A friend has an old 10X that has about 6 or 8" of antenna that doesn't collapse into the case...and he flew an entire flight w/o extending the antenna...kind of embarrasing, but luckily there were no problems. (good ad for an old JR radio, I guess)
02-23-2014, 08:32 AM
#42
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72 works fine and there are very few people on 72 so you don't really have to worry about frequency conflicts. But do check and make sure that there is nobody on your frequency. One more caveat, if you fly both 2.4 and 72 remember to pull out your antenna on 72. Did it twice and crashed 2 planes. I then converted my Futaba 9c to Hitec 2.4 and it works great!
02-23-2014, 12:03 PM
#44
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Very true unfortunately. I paid over $700 for my Kraft 7C in 1980.
Found a 5C on Ebay now for $0.99
http://www.ebay.com/itm/Kraft-5c-Ser...item20e0351207
Found a 5C on Ebay now for $0.99
http://www.ebay.com/itm/Kraft-5c-Ser...item20e0351207
02-23-2014, 09:47 PM
#48
We've had some people lose airplanes on 2.4GHz, non-responsive to transmitter signals. Reading between the lines, appeared might be related to their aircraft receiver antenna orientation. I've never lost a plane on 72 MHz. Some of us still fly 72 MHz. Never had antenna problems on 72 MHz.
Although 2.4 GHz overcomes the frequency sharing problem, if fliers are not careful about their installations and other precautions, can experience unintended results.
Although 2.4 GHz overcomes the frequency sharing problem, if fliers are not careful about their installations and other precautions, can experience unintended results.
02-23-2014, 11:32 PM
#49
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my 72Mhz still works great i'm not putting it down and if i ever did get rid of it i would make sure to give it to some one so they come into the fold and enjoy this hobby like i did when i started
02-24-2014, 04:00 AM
#50
What to do with 72mhz.? I tossed all my old 72mhz. stuff in late 2006 when I purchased my first 2.4 and never looked back. This is a hobby and as most hobbies; their nothing short of a money pits so I have never looked at any of this stuff as an investment; because it's not.
Some clubs won't even let you fly if your not on 2.4 now and many of the larger flying events are the same, no 2.4, no fly... Anyway, that is my take on it.
Bob
Some clubs won't even let you fly if your not on 2.4 now and many of the larger flying events are the same, no 2.4, no fly... Anyway, that is my take on it.
Bob
Last edited by sensei; 02-24-2014 at 04:06 AM.