pete59
Member
Please help me with an interference problem on my MF 65.It is a gas model and radio has some interference when tractor is running. It is wired straight to battery.Thanks.
radio interference
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Soundguy
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a few things you can do.
1, run an 'L' or a 'PI' filter
2, use carbon core 'supressor'wires and not oe style metal core spark plug wires.
3, use resistor plugs.
the latter 2 have spark intensity issues.. so if the L or PI filter handles the job.. I'd forgo the secondary resistors.
a L filter is an inductor (choke) inline with the power wire, and a single filter across power and ground(after inductor ).
a pi filter is the inductor in the power wire, and a capacitor across the power to ground both ahead and after the inductor.
I'd use a high farad value capacitor.. at LEAST 1000UF if not higher like 2200UF .. heck.. i've made filters for police cars with hi output alts back in the day, that used 4700uf and even 6800uf capacitors in a PI setup.
also.. a large value inductor will yeild beter results than one with lower 'henries' i'd reccomend 300uH minimum
for S&G's you could put a torrid core in the power distro too.
google choke input filter and capacitor input filter for more info.
ignore references to any butterworth filters
soundguy
1, run an 'L' or a 'PI' filter
2, use carbon core 'supressor'wires and not oe style metal core spark plug wires.
3, use resistor plugs.
the latter 2 have spark intensity issues.. so if the L or PI filter handles the job.. I'd forgo the secondary resistors.
a L filter is an inductor (choke) inline with the power wire, and a single filter across power and ground(after inductor ).
a pi filter is the inductor in the power wire, and a capacitor across the power to ground both ahead and after the inductor.
I'd use a high farad value capacitor.. at LEAST 1000UF if not higher like 2200UF .. heck.. i've made filters for police cars with hi output alts back in the day, that used 4700uf and even 6800uf capacitors in a PI setup.
also.. a large value inductor will yeild beter results than one with lower 'henries' i'd reccomend 300uH minimum
for S&G's you could put a torrid core in the power distro too.
google choke input filter and capacitor input filter for more info.
ignore references to any butterworth filters
soundguy
Soundguy
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pi better than L !!!
all that said.. the spark gaps are gonna make RF.
another option is an EI module....
all that said.. the spark gaps are gonna make RF.
another option is an EI module....
OP
pete59
Member
Thanks I will see what I can find.
Soundguy
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find? i doubt you find a pi or l filter.. you can simply hit a radio shack and make one.
1 inductor and one or 2 EL capacitors..
1 inductor and one or 2 EL capacitors..
Soundguy
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ps.. don't install anything inline with ground.. leave ground intact. only install inline devices like the inductor in the power wire... of course capacitors can reference ground.
installing an item in the ground line will create a potential difference, ground loop and hum sometimes..
installing an item in the ground line will create a potential difference, ground loop and hum sometimes..
OP
pete59
Member
Could You please elaborate Soundguy as electricity is not my specialty or would a radio shack rep have an idea for a novice? I'm from the 8 track days.
ThomasH
Gold Member
If you search ebay or Amazon for a Legacy LN71 12 Amp Noise Suppressor, I think that is what you are looking for. It installs in the 12 volt power supply line at your radio (as close to the radio as possible) and is simple to hook up.
k0ua
Epic Contributor
Ok my 2 cents... what is the problem? Ignition noise? Pop pop sound at idle andincreases to a buzz with increasing RPM from the spark plugs and wires? or whine from alternator? a high pitched whine sound that varies in pitch with rpm's. If it is ignition noise, first thing is switch to carbon filled wires and suppressor (resistor) plugs. If alternator whine then a choke/filter is called for. Also make sure the antenna coax shield is grounded at the antenna well. Also grounding and bonding of chassis parts is important. You can go to this site: K0BG.com and look under the ignition tab for starts.. then look under bonding and grounding for ideas. Note also the information on wrapping the wires with flexible copper tape.. Lots of good information on the K0BG site. It is amateur radio focused, but the information applies to your receiver also.
James K0UA
James K0UA
Soundguy
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adding a few caps here and there will usually help too, even if using the inline choke.. ditto what was said on the ignition noise.
ps.. no.. most rat schack employees don't know a capacitor from a choke.. nor their application..
ps.. no.. most rat schack employees don't know a capacitor from a choke.. nor their application..
k0ua
Epic Contributor
Remember the old days when rat shack guys actually did know a few things and could identify most discrete components and know what most of them did.? It has been a while, but it is rare to find one that can help you with anything of that nature. And the selection of parts is pretty slim nowadays.
James K0UA
Soundguy
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yep.. they know cell phones now.. that's about it.
It's probably been 20-25 ys since i knew a rs employee that knew anything about those blister packs that had items with tinned leads on them..
257NH
Silver Member
Just go to radio shack and pick up a ferrite core (they may call it a choke) it snaps open,you wrap the power wire going to the radio around it 8 or ten times and snap it shut.If the noise is coming in on the antenna just buy a bigger size choke and do the same thing.
Brian
Brian
Soundguy
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very little work yeilds very little results.
a minimalistic approach like that is sure to yield sub-optimum performance.
a minimalistic approach like that is sure to yield sub-optimum performance.
257NH
Silver Member
Im A ham operator I know from which I speak,well usually ;-)
k0ua
Epic Contributor
So are we... and there ain't no free lunch.. and darn few problems of this nature are easy fixes..
James K0UA
k0ua
Epic Contributor
For one thing.... with a rat shack split ferrite core, it is unlikely to even know the mix of the ferrite. Many of them are surplus cores that are repackaged with no information of their permeability Plus we don't even know for sure what band of interest he is having trouble with (540-1710khz or 88 to 108Mhz) AND we don't, or at least I don't know if the problem is alternator whine or ignition noise or what, and I don't know the method of propagation into his receiver. It might be induced on the power leads, but I don't know that. While the OP can check out some of the links and ideas posted here, without experience and electronic knowledge his probability for resolving this problem is low. There I said the same thing Soundguy said, but in a different more verbose way
James K0UA
James K0UA
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257NH
Silver Member
Pete I sent you a pm,also keep your grounds as short as possible.
Brian
Brian
Soundguy
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Like james said. so are we. had my ticket for decades.
KE4RRD
and again. your 1$ 1 minute approach is unlikely to offer much relief to his issue. Plus we need more info.. plus the op needs to do a lil testing and get back to us.
soundguy
