Stopping channel bleed over for locals.

[8113 Northern MN]

For those of you who follow chat or frequent 38lsb youll already know that I am an avid skip shooter. I work from home and the radio is in front of me all day long. On really good days where skip is rolling I cant help but yell out over and over. Problem is, locally we have a very large group of CB users. Some of them like to listen more then talk, and others like to take it to another channel and talk to each other. Anytime I turn on the radio if some of the locals are talking on another channel its very easy to find them....I just follow the static that their bleed over makes. Now, while Id never ever ask anyone to "fix their radio" or "stop running power"..... I was recently asked very nicely to lay off the radio for a bit because they were worried that I am over doing it and gonna bring attention to our little rural community.

So that brings up my question in regards to the thread title. What are some things I can do to my setup to minimize or even completely stop the bleedover that my setup has onto other channels? Is there even anything that can help or is that just the way the radio ways work? Ive put alot of time and money into my setup and making sure I have great audio fo those long distant contacts...but this whole time ive never taken into account the effect it has on those very close to me. Any help in this area would be greatly appreciated.

 

[Captain Kilowatt]

For starters if you run an amp make sure it is class AB and do not overdrive it and try to get every last milliwatt out of it. Make sure the radio does NOT have the modulation limiter removed and if you run an amplified microphone do not run it too high. Also if your radio has had a "peak and tune" I hope it was not tuned for everything it can put out. The harmonic filters in the output stage of the radio are often buggered with to show more power out but only result in more crap out. Those are the basic starting points that will cover the vast majority of the issues.

 

[8113 Northern MN]

Hey Captain, yea those are the basics of what I covered with my knowledge of CD radio already. Im really stumped here. Im currently running a Galaxy DX-949 with a Ranger Noise Cancelling Mic. I have a Palomar Class AB 500 Watt Linear which I make sure never tops out over 400 when Im shooting across the pond. Shooting stateside I mostly just use the Low setting and the meter reads right over 200w. CB has had some work done to it in the form of Dual Final mod. Has an IRF520 Driver and two IRF520 Finals. Radio also has a Blue Viagra-B board installed for extra channels. Even though I have the option to really push this radio because of the final mod barefoot it is set at 25 Watts PEP maximum. Just enough to drive the linear and stay in the zone I get the most "clean audio" compliments.

 

[dc2rf]

CK gave you excellent tech tips but...

Maybe I'm wrong, but it sounds to me like all of you locals are just too close to each other to expect no bleedover no matter if your "clean" or not. Let's assume you're all running power. Your 400w is one heckuva level to deal with locally. Now I doubt that anyone is going to run just barefoot to help the other guy out, so it looks to me like interference is inevitable.

 

[Draxx]

Using a beam antenna would certainly help direct your signal and minimize bleed over for your friends. However, if everyone is within close proximity it may not help enough or at all. Good luck....... 73's

 

[Mustang 131]

Most spatter is from your negative modulation trying to go below zero. If your running AM use a scope. They are dirt cheap, easy to setup and gives you the info needed to setup a clean station.

 

[Dipole]

Maybe I I'm daft but I believe the question posed by 8113 was what he could do to help out the receive on his station because of all the dirty stations around him. Installing a Beam would help a little if the dirty stations where off the side and some what if in the rear but if he needs to swing around to a different direction then there is no advantage. Unfortunately unless you raise an issue with Uncle Charlie or confront the dirty operators and educate them on how to clean up their stations there isn't much that can be done..... Well you could Move

 

[dc2rf]

Using a beam antenna would certainly help direct your signal and minimize bleed over for your friends. However, if everyone is within close proximity it may not help enough or at all. Good luck....... 73's

Murphy's law postulates that the direction of the beampath needed to work that choice dx station you've been looking for will inevitably be the same beam heading of the local station you're trying to minimize signal to. ;-)

 

[Tallman]

I also tell my 11 meter friends to run low pass filters before and after the amp. Amps are garbage in garbage out. If you feed it a crappy signal you have a much stronger crappy signal to deal with, and so will all of the people of your town.

 

[8113 Northern MN]

Hey guys thanks for all the tips and advice. And yes we are very close. I am 2 blocks from one person and there is another 2 blocks on the other side of him.

Just to clarify, Im looking for things I can do to stop MY station from bleeding over and affecting them. Im trying to stop them from having to deal with the negatives of my station.


As for scopes...I hoestly have 3 right now that ive purchased for my shop and working on all the other electronics that come through. I bought them awhile back and never got a chance to learn how to use them correctly or with a CB. Ive been so overwhelmed with work and the remodeling of my shop and being prepared for the upcoming winter that they are sitting collecting dust right now! It is definately a must do for the winter season!

These are the three scopes I have in my shop all in perfect working condition. Just havent gotten around to learnign to use them. Most of my shops work is Computer and TV repair and I bought these JUST in case one day I needed one for some project. As I have gotten more and more into the CB world and perfecting my system Ive wanted to learn but lack of time and where to start have stopped me haha.

Elenco 25mhz Oscilloscope S-1330
Elenco 40mhz Oscilloscope S-1345
BK Precision 60mhz Oscilloscope 2160

 

[Robb]

Most spatter is from your negative modulation trying to go below zero. If your running AM use a scope. They are dirt cheap, easy to setup and gives you the info needed to setup a clean station.

I'd agree with most of that statement; except for the 'trying' part.
Apparently, they try too hard and do it too often and succeed most of the time.

Interference is a two-way street. One or both radios have little filtering for adjacent channel rejection and if both are over-modulating they will interfere with with each other. Most CB radios with the exception of a rarified few really aren't up to dealing with it because of design and the need to keep unit cost low. IOW; the receiver section is built a bit too thin and on the cheap.

A scope is one way to see if your station is outputting a dirty signal as far as negative peak clipping is concerned. It does nothing - however - for spurious signal detection.

If your radio is throwing odd nasty goo; then:
*You have cut out the AM Limiter
*You have the mic gain above 100% modulation and/or your power mic is set too high
*You have detuned or disabled the 54mhz trap filter thinking you are getting a couple more watts out
*Your antenna is a bleed stick, like a A-99 or a Big Stick/others
*You are too close to the other station

I'd agree that a beam can help

I'd agree that all bets are off for a clean station if you use an amp . . .

 

[8113 Northern MN]

Im running a Imax 2000 as an antenna. I have not clipped any modulation limiters nor tried to squeeze any extra watts out of anything. Ive prided myself on clean clear audio and thats what gets the smiles out of me when DXing. I let the amp be the power i throw out while the radio I only let run slightly above stock.

So yea, feels like its just a matter of us all being too close. Even running a radio that has never been touched at stock settings barefoot we all bleed over for each other.

 

[222DBFL]

With being so close its going to be hard to keep from bleeding on each other. Best you can do is turn the rg gain down some. Being so close you have to have a good group of guys that don't mind letting the big stations talk dx every so often. I Think that making a habit of it with others on the channel may not be the way to go. I run power occasionlly and also when talking with my locals I turn my power down as much as possible. Heck at 2 blocks you could use walmart 2 way radios to talk lol. But yeah it's about being respectful as possible, a lot of guys like to wait until late at night as there aren't as many people on as well. Best thing to do is be respectful as possible. JMO. God bless.

 

[dc2rf]

I don't think this is an issue of cheap CB's. I've seen some pretty good rx front ends on quality CB's.

Even without "power" (especially when the stations involved have good antenna systems), the distances you describe are very close and the rx front ends of ANY equipment take a beating.

Ham ops have the same problem at those distances. It's just "physics".

 

[Captain Kilowatt]

I don't think this is an issue of cheap CB's. I've seen some pretty good rx front ends on quality CB's.

Even without "power" (especially when the stations involved have good antenna systems), the distances you describe are very close and the rx front ends of ANY equipment take a beating.

Ham ops have the same problem at those distances. It's just "physics".

I have to disagree a bit on this one. Many years ago I had a neighbor that ran a hopped up CB and a dirty amp on SSB while DXing, I ran an Icom IC-735 with 100 watts max. Whenever we were both on at the same time I tore the neighbor up really bad especially beaming to Europe which was in the same direction as the neighbor,pretty much all across the band because of my strong signal and not because I had a dirty signal. I could start to hear a little buckshot 20 KHz away getting progressively worse the closer I got. The IC-735 was triple conversion with GREAT filter skirts. The thing with ham gear is you have tighter filters that are better to begin with as well as the ability to adjust those filters and disable the front end preamp to prevent a lot of crap produced inside the receiver from being hit with strong signals.