Paul james 8 Posted April 23, 2018 Share Posted April 23, 2018 Some of you may recall that I asked last year about the merits of 35mHz against 2.4gHz radio gear. As a result of the responses I got I've stuck with my trusty Futaba 35mHz stuff with no issues since. I have a couple of really tidy Futaba T9CP transmitters with synthesiser modules fitted and have found them very good. There is no channel conflict in our club as only a couple of us still use 35 and have dedicated channels of our own. I'm looking to put a petrol engine into a 1/4 scale Pup and already have a Stearman model with a DLE 20 fitted so wondered if there is any advantage to fitting say an frsky 2.4 module as far as interference resistance is concerned? Is there any difference in using a PPM or PCM 35mHz receiver as far as ignition interference is concerned? Title says 3mHz in error Edited By Paul james 8 on 23/04/2018 17:55:01 Quote Link to comment Share on other sites More sharing options...
alex nicol Posted April 23, 2018 Share Posted April 23, 2018 Whilst I'm no expert, if it's any use I've been running a zdz 40 in a falcon aviation Eurobat on 35mhz for 12 years with no issues. Initially on a futaba ff9 and more recently on a Futuna 12z. the only advice I'd offer is keep all the ignition, power and Ariel wiring as far apart as reasonably possible (not sure if this would make any difference but I felt it was a sensible step) Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted April 23, 2018 Share Posted April 23, 2018 Whether 2.4 or 35, good installation practice needs to be considered. Certainly the RF link with 2.4 is very robust, but there's still plenty of scope for the rest of the system to be affected by a poorly installed and/or poorly shielded ignition system. Going back to the old days of 35 ppm & pcm, I know that quite a number of models were lost with pcm lockouts/failsafe with HT ignition interference, whereas a ppm system would glitch its way around the sky but still give a fighting chance of recovering the model. I hated 35 pcm, never used it, saw so many good models lost for what appeared to be no good reason. Never had a glitch (that I noticed anyway) with ppm. Quote Link to comment Share on other sites More sharing options...
alex nicol Posted April 23, 2018 Share Posted April 23, 2018 Apologies I should add it's the same 35mhz PCM receiver in the Eurobat which was fitted on recommendation of the engine supplier Quote Link to comment Share on other sites More sharing options...
Paul james 8 Posted April 23, 2018 Author Share Posted April 23, 2018 Is the braided shielding around the HT lead very effective? I'm not sure why the ground connection for the spark plug body isn't via the engine casing like a car engine is? It would be easy to have a simple ring tag under one of the head of one of the mounting bolts. I've been advised to put ferrites on the ignition battery cable. Up to now I've only used glow motors, maybe I should just stick a big Laser up front and stick with what I know Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted April 23, 2018 Share Posted April 23, 2018 Paul, don't loose sight of the decades that we used 35meg and petrol ignition engines successfully. Screening and ferrites are used, and don't ignore ferrite rods, just as effective with long leads Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted April 23, 2018 Share Posted April 23, 2018 Ran mine on 35 for a long while, follow the usual instal advice, I used ferrite rings as well. Never a glitch. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 23, 2018 Share Posted April 23, 2018 Posted by Paul james 8 on 23/04/2018 17:53:56: Title says 3mHz in error Edited By Paul james 8 on 23/04/2018 17:55:01 Now corrected..... Quote Link to comment Share on other sites More sharing options...
Former Member Posted April 23, 2018 Share Posted April 23, 2018 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Geoff S Posted April 23, 2018 Share Posted April 23, 2018 I only have two models with petrol engines and both are on Multiplex 35Mhz IPD synthesised receivers. One has a Zenoah 26cc magneto ignition engine. Advice at the time I put it together was to keep any electronics at as far as possible from the engine and to aid that I used a wooden dowel, rather than my usual at the time method of a bowden cable, to operate the throttle. Never had a glitch and I used to fly the model a lot. The other has a 30cc Mackay with electronic ignition. The ignition module is separately powered from the receiver/servo pack and is switched both mechanically and with an electronic switch controlled from the transmitter (I have 3 ways of stopping the engine 1: the electronic switch, 2 the physical switch and 3 closing the throttle completely from a transmitter switch. There was fourth, undemanded method until I replaced the ignition unit . Other than that I had no interference issues. I was careful with the installation in both cases. I don't think using a spark ignition engine is a necessary reason to change over to 2.4gHz but there are lots of others. I suppose if I flew my petrol engined aircraft more frequently I'd change over to 2.4gHz for convenience but for no other reason. Geoff Edited By Geoff Sleath on 23/04/2018 21:04:44 Quote Link to comment Share on other sites More sharing options...
Paul james 8 Posted April 23, 2018 Author Share Posted April 23, 2018 Posted by Steve Hargreaves - Moderator on 23/04/2018 20:33:11: Posted by Paul james 8 on 23/04/2018 17:53:56: Title says 3mHz in error Edited By Paul james 8 on 23/04/2018 17:55:01 Now corrected..... Many thanks Quote Link to comment Share on other sites More sharing options...
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