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CB Band and CB Radios
All things CB. Discuss what you do with your CB as well as review and ask questions about AM & SSB CB radios.

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  #11 (permalink)  
Old 06-18-2008, 10:50 AM
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Quote:
{This widens up the TX repsonse on AM} Why for ? please explain ?
Because some/most people like a richer sound on AM. The same reason most people replace a stock mic with a better one.
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Old 06-18-2008, 11:33 AM
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a richer sound on these ? OK the 600 ohm stock mic's that always came with those sounded very good to my ear hole . (especially in the car would also help with back ground noise and always sounded good on SSB) If one were using the radio for a base , again , you want "richer" sound ? Put a Shure 526-T on it and sit back and relax a arm distants away from it . It would surely sound "richer" . I could speak for some but never most. (you can ?) Been around to long and listened to many of those radios without a damned thing done to them over the course of 3 decades.(most guy's used D-104s on them)

IM not trying to argue your point of "better" here or what you believe , I don't doubt it , I just don't think a lot of the foo foo extra's on these are necessary for your average cb AM/SSB operators. I just can't see how you can say "most",at least not from my side of the world over the years.

I put a major mod list there , if one feels the need for "better" on a radio that is already "better" they can have at it. I would just like to say I've had at least a dozen of these radios over the years , and like my writting , I've hammered on them for hours in and hours out without any kind of extra mod's done to them , never once did I have a problem with any of them

Was I lucky ? I truly doubt that. They were just well made radios from the get go. You said some people would like to sound richer , well how much richer is richer on a radio with outstanding audio to begin with ? If I wanted superiour everything out of a radio as all these mod's are supposed to ad up to ? I'd buy a Ham radio .
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Old 06-18-2008, 08:53 PM
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hi switchkit,

the mb8719 dual conversion chassis is my all time favorite too.

this mod is not something you would be interested in.
i imagine most mods to these you are not interested in.LOL

cb is different things to different people. some care more than others what the person on the other end hears. there is no right or wrong here, just different.
(i know you already know this)

the R114 mod is about frequency response, for example, if the radios frequency response in stock form is, say, 200hz-10,000hz; then this mod would make it wider, like, say, 70hz-20,000hz. (those numbers are by no means meant to be accurate, just for example)

no matter what mic you hook up to the radio, it will only pass the frequencies in between these limits.
this mod widens those limits, allowing better mics to do their job.

i can tell you this, my voice no longer sounds "tinny" at all with my D104 silver eagle. not that it sounded bad before, but D104's are not known for their bass response. mine sounds nice and full.

SK, i would never mind buying radio from you, because i would know it hasnt been hacked up.LOL

take it easy,
LC

BTW, that is my friend jon's site you linked to. he is also a fan of this mod.
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Old 06-18-2008, 09:25 PM
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Quote:
Originally Posted by loosecannon View Post
hi switchkit,

the mb8719 dual conversion chassis is my all time favorite too.

this mod is not something you would be interested in.
i imagine most mods to these you are not interested in.LOL

cb is different things to different people. some care more than others what the person on the other end hears. there is no right or wrong here, just different.
(i know you already know this)

the R114 mod is about frequency response, for example, if the radios frequency response in stock form is, say, 200hz-10,000hz; then this mod would make it wider, like, say, 70hz-20,000hz. (those numbers are by no means meant to be accurate, just for example)

no matter what mic you hook up to the radio, it will only pass the frequencies in between these limits.
this mod widens those limits, allowing better mics to do their job.

i can tell you this, my voice no longer sounds "tinny" at all with my D104 silver eagle. not that it sounded bad before, but D104's are not known for their bass response. mine sounds nice and full.

SK, i would never mind buying radio from you, because i would know it hasnt been hacked up.LOL

take it easy,
LC

BTW, that is my friend jon's site you linked to. he is also a fan of this mod.
Thank you for taking the time to explain . Nothing wrong with "better" on top of "better" Boy ! You talk about old school , tinny huh A nice golf sock or sock of your choice would always work nice too I personally liked the Shure 526-T as is on those radios. .......Your right , not so much the mod's other then extra channels / 10 khz jump / and open the RX/TX , the AM voltage regulator is a good call (if needed) I only ever had to change one on a Cobra 2000 years ago. (it wasn't mine) and a npc "type" mod for AM use with amp.

Is Jon the Grant XL guy ? Why in God's name did he shut his site down ? (if it's the Grant XL guy) and speaking of D-104s , never liked them on SSB on those radios unless they were non-powered or used the 10D heads on the powered versions. Thanks for explaining that to me , I honestly wasn't to sure what he meant . SK (I also think that "Hacked Up" can sometimes only be in the eye's of the beholders)
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Old 06-19-2008, 05:32 PM
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shure wish i could get my hands on a shure 526. nice mics.

no, jon is not the grant xl guy.
a member of my yahoo group had some of the files from the old site saved on his machine, and he uploaded what he had to our files section.
jon got it from there and put it on his site.
yes, very cool info there.

jon is living in sacramento now.
he's a pretty darn good tech, but hasnt gotten a shop together yet since his move.
i think you are further south than that right?
LC
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Old 06-19-2008, 06:25 PM
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Los Angles / San Bernardino , So.Cal. as they say.
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Old 06-19-2008, 07:15 PM
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Quote:
Originally Posted by silver dollar View Post
can i change resister 114 for a 10k ohm for a better audio response
You can do it if you like. That resistor is on the audio input line running to the audio amp when in am mode. That resistor is right after where the audio is switched between the balance modulator input ( sideband mode) and audio amp ( am mode).

Its somthing like a 20 or 25 meg resistor thats is in there in a stock radio.
Loosecannon has the right idea. Its a resistor in series with a cap.... its a basic low pass filter... it cuts off a certain spectrum of audio. By changing the cap you change the tone to higher or lower... just changing the cutoff point almost.


It will brighten up the audio and lets a little more drive in the audio amp. Alot of these type of filters can make the audio sound either muddy ( if you go too bassy) or really tinnie depending on what cap you use. This is why changing the resistor is better.... instead of cutting off the lows or highs... your increasing the bandwidth of the filter and its lets more audio tones through.

Loosecannon had the right idea.
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Last edited by bushwacker; 06-19-2008 at 07:34 PM.
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  #18 (permalink)  
Old 06-21-2008, 07:50 PM
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thanks for the flowers bushwacker!

just so everyone's clear; i didnt invent this mod, i just found it, tried it, and liked it.
i do it to all my mb8719 radios now.

LC
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Old 06-24-2008, 08:57 PM
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Hello Gentlemen,,I think the ole Cobra 148 gtl/2000 gtl/uniden grant xl,
or any others with the same pcbs.Where the best of the Best.
I would put them up to a galaxy anyday.And ive owned almost all of the big
export monsters at one point or another.The old 148/2000
will blow them away anyday.Expescally on receive.I happen
to think galaxy has the sooriest recieve of about any.
The nb/anl does almost nothing on them,pitaful.
But that ole 148/2000 pcb with dual gate mosfets are the
cadillac of there time and most all time so far.
I have onwed several of them,and never had a problem.
Nothing major anyway.Maybe a cold solder or something simple
like that.But thats about all.The ole cobra 2000 gtl is one of my
favorite base.And the 148 gtl as far as mobile..But really i always
loved just running my 148 as a base setup,on a good power supply.
Same perfomance.And didnt take up as much room on the desk top.
I really regret getting rid of my cobra 148 gtl.And the ole 2000 base.
I thought like alot of the new comers though.That all that swang
was thang.But now after 18 plus years of talking cb..And over
10 years of working on them.That all that swang stuff is just
feel good medicine.It doesnt make a radio.Id rather have
a good 148/2000 over galaxy/big export rig anyday.Dont get me
wrong the galaxys are a hammering radio.But for all over
performance.. rx and tx,its hard to beat the ole 148/2000
and similar chassis radios.They are great for am and real good
on ssb too.But dont be fooled by the new 148.They are as far
from the ole trusy 148 gtl of the past,as daylight and dark.
As a young lad,when i first started in cb..like i said earlier
i thought if a radio was not swinging 20-30 watts it wasnt getting
out..But i got a lesson a few years later.That was really awake up
call..And ole friend of mine,whom i talked too every night,And i
were chatting on the cb.When he said let me hook up another
ole radio,and see if it sounds o.k..10-4 i said,im a listening.
When he came back online,wow he was shaking the windows loud.
Man i said what is that your running..And how much is that
thang doing on he watt meter.Oh about 3 swanging to about 4
I said 300 swinging 400 huh..No 3 watts to 4 watts.What i said
you got to be joking.Anyway that 4 watts,was talking circles
around his 2517.And it was doing close to 60 watts on 24 volt.
I couldnt believe it.So i went over to his house the next day.
And there it was.A big ole shiny DAK..What a radio i said.
But i know you had to be joking about it just doing 4 watts man.
No,thats all she did..It was a clean non-modified Dak..And now
the rest of the story.I was so impressed about how good that
ole rig sounded.And how great it looked.I just had to have it.
It took me awhile to talk him out of it...But im looking at the
ole beast now.On a special shelf of its own.And i have approx.
100 cb radios.and have owned probably ten times that much
though the years..And out of all of them.My favorites were
That ole DAK..THE COBRA 148 GTL,2000 GTL/uniden grant
AND MY OLE ROBYN YELLOW BIRD T-240D and the Ole honest abe
teddy r/ and all of that pcb type....Have fun with the 148 its
a good one..And like the other guy said.They are a very good
radio stock.Sometimes the more you do to something,that
just more to go wrong......
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  #20 (permalink)  
Old 11-22-2008, 11:53 AM
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Just in case anyone wants to know,this mod does work well in the new China built 148's. Just did it and have gotten nothing but great reports!
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