Hello chaps I’m looking some advice with my cb setup in an ERF ECM.
Rig is a Midland 78 multi and antenna is a sirio mythos 9000 with a electronic-ground-plane and this* voltage dropper, and is SWRing very low indeed however there’s a rythmic buzzing comming through almost filling the power meter and it needs the squelch up to near max to cancel it. It happens wheather the engine is running or not and to totally rule that out I got an altenator interference suppression thing wired in between the voltage dropper and the cb.
Is it likely to be the cheap and nasty voltage dropper causing my problems?
My first thought was the alternator, but then you said engine running or not, so that rules that out.
(However, i would have thought the alt. suppressor needs to be directly on the alt. itself).
I would tend to agree with you that it might well be the dropper.
Could you make up a temporary long power lead culminating in a cigar lighter plug, park you car next to the truck (or indeed from another truck parked along side, with a 12v socket) & try powering it up from that & see if your hum disappears?
Very, very, long time since i messed with CB’s.
PS. Assume you’ve tried it other than just parked in the same place where it could be picking interference up from something?
Just cos you cant hear any sound from the voltage dropper doesn’t make it ‘silent’ - especially electrically!
Is everything properly earthed ( ERF - plastic cab!)? Rig, dropper, aerial? All of it? Are you sure? A dodgy earth is the biggest thing that can cause problems and dont rely on the SWR reading as that can be false to!
Then of course, its down to - ‘Ya pays ya money …’ Don’t buy cheap if you expect the biz!
pete, this is a fairly easy one, or simple one anyway, you get a lot of nosie coming through your cb eng run or not yes! and most poss can only hear people a few hundred yards say?
it is a dropper fault or should i say INVERTER! THE INVERTERS are used for all types of things like fixed in cab phones,12v fridges etc, some trucks come with them as std fitment these cause cb problems no end, the cf dafs “early models” and ivecos “early models again” had these type of droppers “” inverters" fitted and they needed to be cut out completly to stop the interferance coming through, it isnt no good just turning everything of as the inverter will still be running power etc and cause you to have noise,
SWR is nothing to do with noise all swr does is match everything into 50omhz, and the weakist part to that is the ariel as the cb is 50 omhz, coax is 50ohmz,
even earths arnt much to do with noise either,well problem of that much noise coming through your cb,
look and find the invertor and disconect it completly and see if the noise goes away , droppers and inverters are diffrent but do the same job inverters are more stable and slightly cheaper , hope this may help and make a little sence to you,daz
Regarding everything being earthed its through the cigar lighter socket and the egp on the antenna takes care of that. Its not enviormental as the other truck parked beside doesn’t get the interference at all however its a far newer ECT with direct 12v outputs which leads me to believe it is the dropper. Also this particular intereference suppressor (from Halfords) is supposed to be at the radio itself as it has 2 input wires and 2 outputs.
Anyone recommend a quality dropper, or anywhere else on the truck to get a “good” 12v supply (head unit mabye?)
Smee:
I don’t know how you get a CB to work at all in a plastic pig…
I thought that as i began to read the OP. but then the EGP is mentioned. I don’t really know what an EGP is, but, powers of deduction tell me its something to overcome the having no metal ground plane problem.
Smee:
I don’t know how you get a CB to work at all in a plastic pig…
I thought that as i began to read the OP. but then the EGP is mentioned. I don’t really know what an EGP is, but, powers of deduction tell me its something to overcome the having no metal ground plane problem.
(not well put, but you get the idea).
Thats exactly right.
Ive ordered one of these* so hopefully that’ll do the trick
CB in and working fine now with the new dropper… but the other day I climbed into the passenger seat to clean the windies and what do I see lurking about the passenger side of the center console down low?? A wee hella socket with “12v 180W” stamped on the cover
Ive same hassle in the pig as well… Press brakes and more interference, put washers on interference etc etc… Just a crap earth (Mines goes from mirror mount to door hinge).
, droppers and inverters are diffrent but do the same job inverters are more stable and slightly cheaper , hope this may help and make a little sence to you,daz 
