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CB BANDPASS Filter?

Ok so are you just after suppression of anything coming out of your radio and suppression of out of ban spurious emissions or after better receive audio?

I ask because depending on what is more important there are several ways to cook this bird or skin this cat.

First it would be easy to get much more narrow 8-15 element crystal filter and install in the radio pricey I know. You could get 2-3 crystals of much lower cost and use them in each stage in the radio sharpening selectivity/rejection and making the skirt much steeper. Remember the "Channel Guard" from CBC International back in the 1990's? Like that idea only built on the existing IF stages in circuit instead of on a separate board.

On the output side of things keeping your radio from being a splatter box is easy and not over driving your amp and filtering it's output is easy enough to do passively with passive components. In fact avoiding transformer coupling altogether and going with a tuned input is fantastic medicine plus it always improves efficiency over transformer coupled input and broad band designs.


Everything Bellow is off topic could be fun to try anyways!!!

Audio filtering could remove some trash so you do not hear it at the very least.

I think I recall you in the past mentioning NPC and various forms of audio and rf clipping in the past. While not strictly a filter not in the sense you desire if I understand you right it could be made to clean up the receive audio. Depending on where you put it in the radio you could in theory pass the receive signal through it just like you do audio prior to the rf stage on tx. So it would work in receive just as it does on transmit. The same thing applies to any gadget we normally associate with putting between the mic and radio so eq's noise gates, downward expanders clippers/compressors split band audio processing etc....All of thee things can be used on the receive side of things as well and can be switched in and out. The Cherokee 150 Night Rider even had what it called an "Expander" that switched on receive. It was a separate board that mounted inside.

I know it sounds stupid for me to say the above I am sure but we do stuff like this all the time to tx audio . I have never tried it but I am going to try it now soon. I have 3 kids one going off to college and 2 are Freshmen in High School so as my Great Grandfather used to say " I am as busy as a one legged man in an butt(self censored) kicking contest!". I do not get on here often. I hope some of these idea's even if not directly helpful spur some creative thought on the matter!

I just yanked out my handy dandy 1999 ARRLHandBook and have not found any gems inside of it yet that would relate to this idea.

Since most CB and Export radio audio starts to drop off at or before 2500hz it would be easy to filter anything above that. I think combining the enhanced crystal filtering and the audio idea's you could get to a point where the combination of selectivity and audio processing produce fantastic results.

I know none of those idea's keep the emissions from getting from your antenna to the radio or keep emissions from getting from your radio out to the antenna. I just thought they where cool.
 
https://www.arraysolutions.com/as-10-bpf?search=bpf
Most of my questions are not answered on that page without being able to read the graphs. I can't read them. Not all filters are created equally or do the same thing. I just want clarification on what this product does before purchasing it.
Does this filter work on receive and transmit? Some are receive or transmit only.
Is it a combo of low and high pass filters all in one unit?
So, it cuts above and below its center frequency range? Some are not band pass but are low or high pass?
What is the low cut off mhz? and the high cut off mhz?
Does it have a reject frequency high? and low? at what db? Not all filters have a reject.
How far off reject frequency does it continue to cut or reject?
So, is it infinite from the reject frequency on for ever in each direction away from the pass range?
What is (S21)?
Or do I just not understand? Any additional info is appreciated.
Thanks, Chris
 
I emailed them and array solutions said
"These filters are optimized so the adjacent bands above and below the filter have huge attenuation.
It will attenuate all the way into VHF UHF as well as the AM and medium wave broadcast bands. It goes in front of an amplifier, not after.
We also have the W3NQN designed filters which are equally as good and were migrating to these filters for the future, so you may want to get one of these instead since we will have parts for it. Here is the link.
https://www.arraysolutions.com/w3nqn-10m?search=BandPass&page=3   In the case of 10m band it is a brick wall high pass filter with a notch in the 15m band. For contesters."
Here are the 3 charts.
 

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Radios that throw off a lot of spurious signals above and below the CB band could be contained and rendered harmless in the Ham, government, and commercial freqs.

If the CBs are performing to spec then the harmonics they're throwing off would be unnoticeable in the aforementioned bands.

Ultimately though all you need is a 30MHz low pass filter the likes of what Kenwood make and that would stop the harmonics. There isn't really anything below 11m that'll cause issues for CBs.
 
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I didn't see it on there. I ended up ordering it. I guess I'll find out when I get it. I'll hit it with a tracking generator and post my findings.


Entirely possible I was thinking of another vendor.

I lack test equipment past the rudimentary 12V stuff. Anecdote is one thing, some numbers are another.

I wrote elsewhere: Desperation is the mother of acquisition.

The price didn’t seem high to me. With several other installs to do, it at least would get tried in them all.

Asked Morgan via email if they thought it would be beneficial given my mobile use to connect the pair of coax grounds in a big truck. I truly couldn’t find a change — and instructions not EXACT on this — but now suspect my bad choice of ground point. Their answer was “read instructions”. (Gee, thx).

I’ll try another brand at some point. Mobile needs all the help it can get. No reason not to think it essential — is my take — as maximum 11-Meter clarity is what matters (to me). No stone unturned.

On my 579 Peterbilt thread there is a pic of the device interior with lid removed. (10/27/2019; Post #37)

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