Amplified CBer Filter Solutions???
Chris Schmidt
we splatter, and to other HAMS when we Splatter on Freeband. Anyone
got any Ideas on filtering the output stages of the Cheap linear
amplifieers that most CBers have access to, such as the
; Super Star, Blue Thunder, White tornado, King Bee, 75's-100's and the
200's - 550's, and also the Texas star DX series (200-1600) <- which in
my opinion and experience don't splatter as bad as the rest.
We need to Comprimise, the FCC cannot Catch everone and there
will never be a "worldwide raid" By a wimpy government division such as the
FCC. So If you " TEchnichaly inclined operators could help the rest of them
we would all be better off. Any Mods for those AMps should be posted. It
will save a lil' splatter for the Considerate ones who don't want to splatter
across all 40 channels to make their heads swell.
If you got any Ideas on filtering at all for these amps or just in general
post them or E-mail me and I will send them to an FTP Server for
public avalibility.......
thanx in adv.....
"I love my Radio"
chris
Joe B. Simpson
> Us amplified CBers are very aggrivating to other CBers when
>we splatter, and to other HAMS when we Splatter on Freeband. Anyone
>got any Ideas on filtering the output stages of the Cheap linear
>amplifieers that most CBers have access to, such as the
>; Super Star, Blue Thunder, White tornado, King Bee, 75's-100's and the
>200's - 550's, and also the Texas star DX series (200-1600) <- which in
>my opinion and experience don't splatter as bad as the rest.
Yes. A simple modification that will reduce the splattering in most cases
is adding a simple gamma match just after the final output stage.
Open the amp and locate the SO-239 antenna connector from inside. Cut a
length of insulated heavy-guage wire (#12 is best) *EXACTLY* 6 3/4" long
(this is 1/10 of 5/8 of a wavelength at 27.185 MHz). Strip 1/8" of insulation
from each end, and solder one end to the center conductor of the SO-239 jack
(from the inside). Coil up the wire so that you have a three-turn loop, and
hold the loop together with a twist-tie. Then solder the other end of the
loop to the outer conductor of the SO-239 jack. Close the box back up, and
you're done. This has almost completely eliminated the splatter from every
amp I've ever seen this modification done to. It has the added benefit
of increasing the power output a few watts, because the extra power that used
to be radiated on undesired frequencies is forced to radiate on the CB
frequency you're tuned to.
Catchya on the air!
-joe
10-4!
--
"When personal freedom's being abused, you have to move to limit it."
- U.S. President Bill Clinton, 1994
Andy Domonkos
$40 and I use one in my car w/my 10M amplifier (for HAM use). I don't
agree w/folks using them on CB but at least the filters can help keep
your signal in-band and out of the Ham/TV bands.
Any ham supply center (Like Amateur Electronic Supply in Milwaukee)
sells them.
Andy
Joe B. Simpson
>>
>Barker and Williamson (B&W) make an excellent filter you can use. It's about
>$40 and I use one in my car w/my 10M amplifier (for HAM use). I don't
>agree w/folks using them on CB but at least the filters can help keep
>your signal in-band and out of the Ham/TV bands.
How is a low-pass filter that is useable on 10m going to keep an 11m CB
signal out of the 10m ham band?
-joe
--
"When personal freedom's being abused, | "In Canada we have something called
you have to move to limit it." | multiculturalism - you will find the
| whole spectrum of races living in
- U.S. President Bill Clinton, 1994 | Toronto's slums." -A Canadian
Mike
It's been my experience that most of the problems stem from far too
much audio input--power mics, etc--which causes severe
overmodulation.
If they would only reduce the audio input level and get their
modulation down to an acceptable level, a lot of the splattering
would go away.
Mike
Mike
BLOWIN' SMOKE fer shur! (Read it reeel careful, now.)
Mike
Andy Domonkos
>
> How is a low-pass filter that is useable on 10m going to keep an 11m CB
> signal out of the 10m ham band?
>
> -joe
> --
> "When personal freedom's being abused, | "In Canada we have something called
> you have to move to limit it." | multiculturalism - you will find the
> | whole spectrum of races living in
> - U.S. President Bill Clinton, 1994 | Toronto's slums." -A Canadian
Have you seen what the output of an unfiltered cheap CB amp looks like
on a spectrum analyzer? I have, that's why I put a killer filter on one.
You get spurs above and below 10M. I have since put a kit built amp in
place of the the orignal and seemed to be cleaner but I left my filter
in-line for good measure.
Andy
Joe B. Simpson
>>
>> How is a low-pass filter that is useable on 10m going to keep an 11m CB
>> signal out of the 10m ham band?
>>
>on a spectrum analyzer?
Yes, and I still wonder how putting a low-pass filter with attenuation
above 30MHz on a dirty CB amp is going to keep the splatter out of the ham
10m band.
Andy Domonkos
I added the tuner at the same time I added the filter so the tuner is probably
doing most of the 'filtering' since it's a tuned circuit. It may be worth
going w/the tuner first in that case. Either way, the amp on CB is illegal
and if they do use amps it's probably better to use a filter and/or
tuner combination.
Andy
harr...@vax.sonoma.edu
> In article <6VdBkiub...@access.digex.net> domo...@access.digex.net (Andy Domonkos) writes:
>>>
>>> How is a low-pass filter that is useable on 10m going to keep an 11m CB
>>> signal out of the 10m ham band?
>>>
>>Have you seen what the output of an unfiltered cheap CB amp looks like
>>on a spectrum analyzer?
>
> Yes, and I still wonder how putting a low-pass filter with attenuation
> above 30MHz on a dirty CB amp is going to keep the splatter out of the ham
> 10m band.
OK. Rather than a "low-pass" filter, how about a "band-pass" filter? The low
pass will attenuate above 30 Mhz. but doesn't do didly squat on anything below
your operating band. A band pass filter would cover both above and below where
you are operating.
73,
Ken Harrison
N6MHG
email: harr...@sonoma.edu
Andy Domonkos
> >Have you seen what the output of an unfiltered cheap CB amp looks like
> >on a spectrum analyzer?
>
> Yes, and I still wonder how putting a low-pass filter with attenuation
> above 30MHz on a dirty CB amp is going to keep the splatter out of the ham
> 10m band.
>
> -joe
> --
> "When personal freedom's being abused, | "In Canada we have something called
> you have to move to limit it." | multiculturalism - you will find the
> | whole spectrum of races living in
> - U.S. President Bill Clinton, 1994 | Toronto's slums." -A Canadian
From the beginning, then. If an amp goes into parasitic oscillation as many
do, (mine did) when a signal is applied, you get a wide range of 'noise', not
just 27Mhz, but my analyzer showed noise down below 14Mhz. This 'noise' is
amplified, etc, etc...Putting a filter between the amp and the trasnmitter
AND a filter between the amp and antenna cured the problem. Cheap amp
design w/poor or no matching is probably the cause. Either way, when I
replaced the amp board w/a kit built unit the spurs went away but I kept
the filter in-line anyway.
These crappy amps are a problem, I hear some locals across 10M and find
them by quickly tuning down to 11M. If their amps are generating wide
band spurs and the spurs are amplified, that will interfere with a
whole range of freq's, not just the 2nd harmonics, etc.
Andy
Richard Dale
MT>If they would only reduce the audio input level and get their
MT>modulation down to an acceptable level, a lot of the splattering
MT>would go away.
Not only that, but less is more in CB. Mikes don't need to be
"power mikes". A better plan would be to use a compression mike.
That brings up the low audio level and brings down the high audio
level to a stable level -- you sound louder because everything's
the same.
Linears? I run a Cobra 148GTL mobile barefoot into a $40 Radio
Shack magnetic mount. I've talked SSB to Nova Scotia twice,
Indiana, Florida, Kentucky, California, Alaska that I can remember
off the top of my head. I know a guy who is pleased as punch
that his linear has a High-Medium-Low switch (200-300-400 watts).
It's useless, as there's virtually no difference between those
three.
Of course, people will buy anything. My favorite is the "Skip
Reduction Filter". It was a 25-watt variable resistor in a metal
case. Yeah, it reduced the skip. It also reduced the output power.
* 1st 2.00b #567 * Dehydrated tagline! Just add wat*#&@!)$% NO CARRIER
smt2 test tech login
would just like to take a minute and thank the both of you for listing the
fix to my RF amplifier. The GAMMA Match has been around for many years but was
not well known as it was used primarily with tubes and was only talked about in
the old school. I put one on my amp and my friends were amazed at the
difference it made. I installed it in the morning and was shooting skip
farther than I ever had before. MY radio had an appretiable 18% gain on total
output and on the spectrum analyzer the splatter was reduced to almost 4% from
the previos 32%. It reminded me of the first time I installed headers on my 69
GTX.
I then preformed the same setup on two of my buddies amps and it made them
estatic.
Again I'd like to say thanks. Now I'm BLOWIN A FIREBALL with smoke to spare.
For the gent whom needs dual filtering on his radio I think I,d install a wide
band notch filter and adjust it for the range you desire. I think a dual notch
might be a bit of overkill but it depends on your circumstances. You know those
foreign countrys and how they can be.
I guess a person could even GAMMA Match their radio but I haven't needed to do
that as my unit will dead key at .5 watts and swings to 5watts so my input
modulation to the amplifier is minimal. I would certainly Gamma Match my radio
if it were dead keying and swinging over 5watts it will only suppress the
additiuonal noise that would travel into the Amplifier.
Best Of Luck
LOBO (W7QAR) the wanderer
Levi Sebastian
Over modulation/deviation is the main cause. They will amplify whatever
you send it, so, stop sending the splatter to the amp, and the amp wont
re-produce it. Make sense?
In other words "Put that damn mod limiter back in the radio, and learn
what ALC stands for and why it was designed!"
ten four by golly good buddy cb'er
John F. Woods
>> How is a low-pass filter that is useable on 10m going to keep an 11m CB
>> signal out of the 10m ham band?
>on a spectrum analyzer? I have, that's why I put a killer filter on one.
>You get spurs above and below 10M. I have since put a kit built amp in
>place of the the orignal and seemed to be cleaner but I left my filter
>in-line for good measure.
Have you looked *really carefully* at the spectrum analyzer display after
the filter is installed? Unless you've got a very large bank of high-Q
cavity filters (one per channel), you're almost certainly spreading IMD
products over the entire CB band, and no doubt the amateur 10m band and
whoever has the misfortune to use the region just below 27MHz as well.
Filtering out harmonics and random LO signals is not enough.
Andy Domonkos
>
> Have you looked *really carefully* at the spectrum analyzer display after
> the filter is installed? Unless you've got a very large bank of high-Q
> cavity filters (one per channel), you're almost certainly spreading IMD
> products over the entire CB band, and no doubt the amateur 10m band and
> whoever has the misfortune to use the region just below 27MHz as well.
>
> Filtering out harmonics and random LO signals is not enough.
>
>
I was able to excite my amp from 3.5 - 29Mhz) that parasitics are a norm.
I built my own lower power 10M amp w/tuned input/output and had no problems
whatsoever. The imported special is what caused problems.
Andy
Tim Bandy
Jb> Message-ID: <30h3rp$9...@news.duke.edu>
Jb> Newsgroup: rec.radio.cb
Jb> Organization: Joe's Bar and Grill
Anyone know a good mail order source for CB linear amplifiers?
___ Blue Wave/QWK v2.12
Uncompltd
Bandy) writes:
Try "Communications Concepts Inc.
508 Millstone Drive
Beavercreek, Ohio 45434-5840"
Ask em for a new catalog, you'll be glad you did!