god i love this stuff. where do these general rules come from? answer -
> someone makes them up. 8"....so at 7" its going to be noisy?
>
> how far you need to isolate depends a whole lot on how noisy the system is, and
> sometimes it ain't got much to do with distance. first, PCM will go a long way
> in solving many ignition related interference problems. second, DA and 3W
> engines use shielded spark cables which are extremely quiet, and when coupled
> with a decent receiver, will allow you to stack everything - ignition,
> receiver, pack, main battery packs, all within a couple of inches of each
> other, and there are no side effects. how do i know this? cause we did it, and
> the airplane (a glider tug) is routinely flown to over 1000' and on any given
> day may burn two gallons of fuel. so it works. but your results may
> vary...especially if you use a low end ignition with a cheap receiver ...
Great set of RULES for those who don't HAVE ignition systems provided by your sponsors.
The shields can be acquired for several ignition makers and are reasonably effective at stopping spark splatter, as are resistor plugs.
The problem *I* have had with PCM Rx's and ignition is that it works absolutely great until that day when something in the ignition module raises the threshold of 'noise' a little or the RX develops a little vibraton or age problem. Then, suddenly, you have a flying gasser and NO WAY TO GET IT BACK unless you happen to have the correct "lock out response"! BTDT and it was expensive but worse than that it was scary to watch a 20+ pound bird with a 3 inch engine on the nose fly at WOTwith no hope of recovery. Just stand there and hope it suffers an upset and splashes before it finds people.
No sir, YOUR generalization is not for me either. I will continue to separate my radio equipment from my ignition equipment (of ALL brands as I happen to have several) as much as possible with 12 inches being a goal since MOST (but certainly not all) ignition module splatter is low powered enough to be avoidable at a distance. Mount them up close and it the IF section of the RX gets swamped with a signal stronger than your transmitter at a distance. In other words, the further from your transmitter the plane fly's, the better the chance it will get rotten.
Since you obviously are so much smarter than I, you are welcome to do it your way.
Jim Branaum AMA 1428
Six_O'clock_High Target snipped-for-privacy@Guns.com