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Cobra 2000 peak mod

akzo1990

Member
Apr 4, 2005
37
0
16
Arkansas
Has anyone done this mod before and if so how well did it work?

"I'm sure most of you know that when you turn down your dead key using VR-10 you also turn down you peak swing. Well I've developed a simple method to enable full power swing from any power range. All you need is a 1N4001 diode. First you need to remove R-194. Place the cathode(banded end) of the diode in the right hole where R194 was removed and the anode in the other hole. That's it, full power swing no matter how low you set the dead key! The audio response is also improved and it makes the radio sound great!"
 

ahhhh.....the (in)famous NPC/RC mod (or part of it, anyway). Look in the Tech section. There's quite a lengthy thread about this mod. To sum it up: It looks good on a watt meter. On a scope it will show you that it's overmodulated. If that's what you're looking for, then great, but it's not anything close to "clean" audio or modulation
 
I suppose it just isn't a perfect radio modding world ? ...did that to my Grant XL ...doesn't hurt the sideband side of things ...(if that's your thing ?) but it did help to drive the amp on AM (PEPper Upper) .....IM no expert here but I do understand what Mole is talking about ...I personally in the motor car used an amp with my Grant but I also only ran a RK-56 Mic /TRB-1 Echo board installed ....I was 100% pleased with the diode mod /the audio sounded like a base station /no back ground/no over modulation to ones ear (mic gains tend to help mellow things out) .....but not to say that I more then likely did a little bit more bleed/splatter then if the radio had been dropped down to 2 swinging 8 with a scoped out 100% modulation driving my little amp on the mighty scope (-: ......this stuff can really not make a whole lot of sence to me at times ??? I've been told the formula over the years and why ....splatter and bleed is basically wasted power to ones given target ....going in all other directions )-: (and maybe more then likely pissing somebody off elsewhere ?) but over the years .......this just doesn't seem to get through my thick skulll !!! if the radio is tuned to the amp and will say it's doing 2 to 20 .....more then likely it's not going to look so wonderful on the scope )-: and one is going to waste power one way or the other .....How much power ? might be a good question ? .........alrighty then ...lets go to the right way to do this without wasting power to ones given target / a clean signal / audio at 100% scoped out ......Hmmmm ? ......so whats it going to look like now ? 2 x 4 I believe the formula is ? ....so if IM doing 2 I should only swing about 8 watts tops at the 100% scoped out modulation (keeping in mind that IM tuned to the given amp of my choice) ....I really shouldn't be wasting very much power at all .....IM sure there's some ...but not like the 2 to 20 stuff .....so what's it all about here ...PEP !! are these mods really that bad ??? Do they really make one waste that much power especially when using an amp ? ......Dirty as they say !! ......IM totally guilty here guys !!! )-: I truly understand the right formula but yet I still can't seem to let myself getaway from the caps and resistors and diodes ...it just has to be that Damned meter of mine !!! )-: but yet it really makes common sence to do things the right way if one really didn't want to waste his or her power else where ...Doesn't it ? Hmmmm ......OH and back to the Cobra 2000 ....../ 148 GTL old school /Grant XLs bla-diddy-bla-bla-bla ......I was never much on the 2000s ......but I basically love the boards (-: ...You just don't have to do a whole lot to them for them to sound good .......to much is to much with those .....or so it would seem to me over the years and to my ears ......but like somebody once said through out the years ......we don't talk to machines .........we talk to people. Switch Kit
 
Has anyone done this mod before and if so how well did it work?

"I'm sure most of you know that when you turn down your dead key using VR-10 you also turn down you peak swing. Well I've developed a simple method to enable full power swing from any power range. All you need is a 1N4001 diode. First you need to remove R-194. Place the cathode(banded end) of the diode in the right hole where R194 was removed and the anode in the other hole. That's it, full power swing no matter how low you set the dead key! The audio response is also improved and it makes the radio sound great!"

"I've developed"... LMAO ! You mean, You read somewhere...
 
That is an old mod. Remember the "super swing "kits???
A molded piece of plastic with several wires coming out of it.
I took one of these apart and 3 of the wires were not even connected to anything!
Plus they sounded like crap...
 
Best modulation blast I ever saw was like this and came from Roger (Nashua Communications) formerly in Nashua NH.
You take whatever 1/4 watt diodes (I can't remember what he used but no doubt allot of different ones will work) configure a basic AC voltage doubler using 4 then put that in line near where the audio dumps onto the driver/final. If that isn't enough solder another one together and run them in series. If that isn't enough make another one,,,,by now you should be picking pieces of to202 casing out of the wall behind your bench.
After all, what is an audio signal but AC current?
Guy had a ton of talent. Used to be partnerswith Lou Franklin.
He developed an ACR filter (the Spectre-T) that out did Lou's ACRs hands down. Heoriginaly developed them for the radios used in F-14s.
Great guy, I learned allot from him and continue to miss his company.
I saw another mod in a cobra 2000 that used a large (by comarison) audio transformer off the output of the audio amp. It sounded great but they guy needed a new audio amp IC every year or so.
I have barely touched a radio since I leftmy lab in 2000 but with the skip cycle coming in again I am back into again.
I need a larger alternator :)
 
The Cobra 2000 & Uniden Madison radio's were never really intended to be big swingers. My Madison was aligned/tuned by Key CB, 2 watt dead key swings 15 and SSB peaks are 17-18 watts. That's right in line as far as proper Cobra 2000 performance as well. What numbers are you seeing?
 
My Madison with an asymmetrical mod done to it deadkeys 3W and swings to 13W, SSB is at about 16-17W. And I'm perfectly happy with that. The locals love the way the radio sounds. No big powerhouse radio, but that's why I have a "little extra" if I need it. :)



~Cheers~
 
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