does anyone know the spec of the resistor in plug cap (3W CDI), I know it is 1K 10%, beside that any other requirement? like what watt and voltage? any risk if I replace this resistor by myself? thank for any input.

Since the whole system is completely shielded, I see no reason to even have a resistor in the circuit...
Anybody have a good reason for the resistor ?
Other than "that's the way we always do it" Monkey see, monkey do ?
Tell me how RF can get past the shielding, resistor or no

Thanks, I guess the role of this resistor is reduce the current drain.

Don't know the reason but when I took the resisters out of the caps on my BME 110 I couldn't get more than 20' away without the servo's going nuts.

Are the caps shielded on the BME 110? Capt,n

Yes, BME uses the Falcon Ignition.

Keith had used CH in the past, which I still prefer.

If you want CH now you have to make a special request. The Falkon is cheaper I'm still of the notion that you get what you pay for.

Falkon with a resister cap--

Well...Whats the rest of the story? Why did the servos go nuts after removing the resistors? Is the Falcon circuit made to use only resistor in caps or sparkplugs? Capt,n

I have Falkons with resistor plugs-- and ZDZ ignitions with out resistor plugs and with resistor plugs th stock ZDZcap has NO resistor in it - -- no glitches - ever
my radios are all JR PCM on Ham Band -have been for almost 20 years .
I put the DA cap on the one in the picture it works perfectly
Don't know why the other glitch problems are occurring

3Dguy,
The wattage determines the size. If you match the size, you will have the correct wattage. Yoy already know the value and tolerance(10%). You might try it without the resister and do a range check at different speeds to see if it matters. Or not.

Dave

You can not use ordinary carbon resistor or replace metal sheet resistance. Must be tolerant pulse of the real core resistance

Dave:
thank, I will try

Do yourself a favour and buy the right part from the OEM. It is not a typical resistor that is used in modern electronic equipment. (Interestingly enough it is a "typical" resistor from 30 to 40 years ago. That is the only clue I will give you.) It must have a very low inductance, which rules out carbon or metal film resistors.

RCIGN1 I have the equipment to measure the radiated noise from an ignition system. I can tell you there is a marked difference between a fully screened ignition (eg DA) with the resistor fitted and the exact same ignition without the resistors in the cap. There is no way I would use an ignition without either a resistor in the cap, resistive HT lead or resistive spark plug.

Your opinion on. Do with the resistance is strong to withstand the impact of discharge pulse. It is precisely because of this. . So he is not ordinary carbon ink or metal membrane resistance. This is the most critical.

Howie..I have no way to test radiation, just 18 years of flying planes with Zenoah engines, from G23s to GT80s, and an occasional Quadra........We started when there were no FM recievers, just ProLine AM systems...Zenoahs have the spark coil mounted on the side of the engine..The wire is solid inside and the plug cap is not shielded...I have never had to use any kind of shielding, either on the wire or on the spark plug...The spark plugs are Champion RCJ7Y....
I must just be lucky...

CM-6 is without resistance, so resistance to interference plus one.

????Nothing Zenoah makes uses a CM6 except the new G20, it has a shielded ignition...

Hi Ralph

The RCJ7Y has the resistor built in so there is no need for a resistor in the cap or carbon HT lead.

Take one of your Zenoah engines and run it with a non-resistor spark plug. You will get no range.

So back to the original point. He has a 3W ignition that uses CM6 spark plugs. The CM6 does not have a resistor built in. Screened or not he MUST have a resistor in the plug cap. The resistor must be a very low inductance, which is not typical of modern carbon film or metal film resistors.

Ian

Howie

Good input, learn something everyday

Thank

The resistor in the cap and also used in the plug are a carbon comp type resistor, most resistors that we typically use in every thing else these days are a metal film type. Carbon composition resistors have allot more inheriant induction that make them that is needed for some ignition output drivers.

I have a C&H ignition with a shielded lead and cap for a CM6 plug. I don't think it has a resistor in the cap.
Works.

My circuits, and C&H circuits, need no resistor in the cap or wire to make the engine run...I made ignitions for 19 years and had no problems until recently...I now use C&H circuits...Bill's circuits draw more current that mine did...The reason for that was the shielded cap with the built in resistor and carbon center wire needs more power to get the spark to the plug..
My ignitions very seldom needed shielding...Maybe the spark wasn't quite as strong, but was still strong enough to run any engine ever tried, including my 289cc racing twin running on methanol...NOT shielded..The plane went 230 mph...
No one has ever been able to explain to me why a resistor is necessary in a completely shielded system....
Zenoahs and Quadras, and all the weedie conversions with magneto ignitions, have no resistor in the system anywhere and work just fine...
Must be a "follow the leader" thing, someone starts it and after a while it becomes standard..
Like large diameter tygon fuel tubing on small gassers
Or six bolt prop hubs..
Or the perception that Zenoahs are overweight underpowered boat anchors

Ralph if you have been using RCJ7Y spark plugs all these years then you have been using a resistor in the circuit. It is built into the plug. You can measure it!! Take one off the shelf and measure the resistance from the top of the plug to the electrode.