rfx 75 in cobra 29 ltd

[johnecashflo]

i have a ? about the cap value at c 42 ..the install calls for a 3300uf 16 volt to replace a 1000uf 16 volt..all i could get at radio shack was a 3300 uf 6.3 volt cap..so i used it.. well it seems to have worked fine ..i was getting good numbers from the rfx 75..but i was worried about the cap burning up ..so i replaced it with the factory cap (1000 uf 16 volts ) still seem to work fine (same numbers on meter)..would the 6.3 volt cap burn up? and what does the c 42 have to do with the proper operation of the radio and the rfx 75?

 

[Robb]

I'm working on a Cobra 29 too, and have a couple of 3300pf 16v caps. If the one you put in didn't pop, it probably won't. But I'd still put the right voltage in it - though. Oversaturating this cap with too much voltage may cause audio distortion - but I'm no tech. This mod is for the audio IC and changes the output response of your audio on TX - or so I have read here. The other mods to this circuit include a 33k resistor and two .2 monolithic caps.
Here is the original thread:
http://www.worldwidedx.com/radio-ra...bra-29-high-power-mod-2sc1969-transistor.html
I haven't found the location of C68; anyone know where to look?

What kind of numbers is the radio putting out with the RFX75? I've heard varieties of reports. Some as low as 60 watts, and some as high as 120. The question remains: what other mods are people doing to the 29's to get these bigger numbers?
That is a thread that needs to be started and explained...

 

[johnecashflo]

c 68 is right next to the final that was removed to install the wires through..only used to raise or lower the deadkey..if your deadkey is were you want it i would just leave it..

 

[Dodgem250]

What kind of numbers is the radio putting out with the RFX75? I've heard varieties of reports. Some as low as 60 watts, and some as high as 120. The question remains: what other mods are people doing to the 29's to get these bigger numbers?
That is a thread that needs to be started and explained...

The most you are ever going to see out of a Cobra 29 with a RFX75 is about 55-60 watts, you have to first understand "what" the RFX75 is. It is not an "amplifier" is a "final replacement" (with too damn many wires in the first place) Basically what the RFX75 unit does is take your stock finals out of line and replaces the stock finals with the mosfet finals that are in the RFX75 unit (ie: ERF2030 / IRF520 upgrade).

The RFX75 is a great gimmick and it makes someone rich, but, it is designed for 10 Meter and HAM units that are designed already designed to accept the RFX75 add on board.

If you think for a second that you'll be seeing watts anywhere near 100-120, you're up to getting feelings hurt. If you want to see actual watts in the 100-150 watt range, do the RM Italy "stinger" boards, which are actual amplifiers, that are driven by the radios stock finals.

If you want to use the RFX75 idea, then just do a MosFet final upgrade and be happy with what you get, then go buy an external amplifier and do it without all the heads you get from something that will never do what you want anyway.

I'm a tech with about 30 years of experience and I just hate to see guys get their hard earned money stolen from them with gadgets like this, but, hey, if you like it, then I too could tell you it's doing 100 watts and take your money, but, I'm not that kind of fella.

Good Luck!

 

[johnecashflo]

if you KNOW what kind of numbers can be achieved from the upgrade why are you asking or worring about it..the question was about the cap value at c42... being a tech of 30 years you should be able to answer that for a doit yourself at home hobbie guy..as far as the wattage goes i dont think my meter would be that far off.. but im NOT A 30 YEAR TECH..well anyway any help about the cap value from the 30 year tech or anyone else who might knows it would be greatly appreciated..BTW..the finals are a 2030 driving a 7530 does that change the final pep of the unit ?

 

[speedracer6g]

I just did the install of one of these the other night and i was getting pretty good numbers out of the radio. I didnt finish tuning everything yet and i am getting 8 watts dk and over 100 watts swing on my bird meter with a pep kit installed. My dosy meter only shows about 70 watts butt it is not a pep meter. All in all its not a bad deal for the money. I just need to tune up the dk a litle and put some finishing touches on it.

 

[Cityboy]

I also installed one on a cobra 29 ltd chrome; and as speedracer6g said he got 70w out of his Dosy as did I. I ran my supply at 13.79-80 and saw these numbers of 75-77w max with a dk of 15w and modulation through the roof. As a 30 yr tech you should know that some of the people saying they are getting those numbers are running their supplies well above the recommended voltage of 13.8v and running in the 14.5-15v. Even though the radio can take it for awhile and the capacitors are usually rated for the 16v, you know it wont handle it for very long without damage somewhere.

 

[1342]

pep pep pep pep there is no pep

The most you are ever going to see out of a Cobra 29 with a RFX75 is about 55-60 watts, you have to first understand "what" the RFX75 is. It is not an "amplifier" is a "final replacement" (with too damn many wires in the first place) Basically what the RFX75 unit does is take your stock finals out of line and replaces the stock finals with the mosfet finals that are in the RFX75 unit (ie: ERF2030 / IRF520 upgrade).

The RFX75 is a great gimmick and it makes someone rich, but, it is designed for 10 Meter and HAM units that are designed already designed to accept the RFX75 add on board.

If you think for a second that you'll be seeing watts anywhere near 100-120, you're up to getting feelings hurt. If you want to see actual watts in the 100-150 watt range, do the RM Italy "stinger" boards, which are actual amplifiers, that are driven by the radios stock finals.

If you want to use the RFX75 idea, then just do a MosFet final upgrade and be happy with what you get, then go buy an external amplifier and do it without all the heads you get from something that will never do what you want anyway.

I'm a tech with about 30 years of experience and I just hate to see guys get their hard earned money stolen from them with gadgets like this, but, hey, if you like it, then I too could tell you it's doing 100 watts and take your money, but, I'm not that kind of fella.

Good Luck!

yes this is false advertising and is probably working very well since most guys these days actually think that the PEP reading there getting is the output.

 

[Switch Kit]

ERF 2030 driving a ERF 7530 , 120 watts pep all day long on a Bird 43P on 2 different Cobra 25s . I guess a pep meter don't count ? These little amps kick ass !! I see nothing wrong with tech's making money on them. I don't see the rip off in any way ,shape or form. 55 to 65 ? you either got a bad one or you need to check your p's and q's . (even if you were talking RMS ? I'd still take it ! )

The last one I got was slightly different from the first one , just had to spread a few of the coils as they were in the first one I did. If they only did 55 to 65 pep ? I wouldn't waste my time. Now you have RMS / AVERAGE / PEP , take your pick . For removing a few parts and drilling two holes and on it's own heat sink , filtered AB , on a CB radio !! This is the product of the year and I think tech's should make some money for there time on these.

 

[1342]

so how many watts is it doing average or in the real world not PEP capacitor watts!

 

[Moleculo]

so how many watts is it doing average or in the real world not PEP capacitor watts!

There is no such thing as PEP "capacitor watts". Average reading meters and PEP reading meters are both "real world". They're just different ways of measuring the same thing. In the Amateur Radio world, the FCC tells us that we must keep our transmissions withing a certain wattage, measured by PEP. So does that mean the FCC doesn't measure "real world"? I don't think so. You need to learn the difference between the two types of measurements before making such brash statements.

 

[1342]

There is no such thing as PEP "capacitor watts". Average reading meters and PEP reading meters are both "real world". They're just different ways of measuring the same thing. In the Amateur Radio world, the FCC tells us that we must keep our transmissions withing a certain wattage, measured by PEP. So does that mean the FCC doesn't measure "real world"? I don't think so. You need to learn the difference between the two types of measurements before making such brash statements.

wrong they are not pep measurements on am frequency is pointless,incorrect,and inaccurate by 2 to 3 times and for your information your pep switch in your meter has a 50 volt capacitor to it thus capacitor watts! have you ever noticed that when using am to check your pep readings the needle falls slowly but on average readings drops instantly thats the capacitor open your meter and learn something new!

 

[MisterFatty]

Wow this thread has quickly turned into Another one of those LOLOLOLOL kinda things.....:laugh: don't bother trying to explain things Mol :headbang

 

[Moleculo]

wrong they are not pep measurements on am frequency is pointless,incorrect,and inaccurate by 2 to 3 times and for your information your pep switch in your meter has a 50 volt capacitor to it thus capacitor watts! have you ever noticed that when using am to check your pep readings the needle falls slowly but on average readings drops instantly thats the capacitor open your meter and learn something new!

Nope, all but one of my meters that have a peak circuit are active peak meters, meaning they aren't powered by a capacitor. You ought to take apart a Bird 43P or any other active peak meter before continuing on with this nonsense much further. Yes, cheap meters with a PEP switch just use a capacitor to hold the needle element. They're not real accurate, and everyone knows this...it's not like you just shed light on a mystery that we are all blind to. But that's not how quality meters with an active peak reading circuit work.

What I was trying to help you understand was that there is a purpose for both methods of measuring output. You can't simply dismiss one of those methods as "fake", especially if you lack the understanding of what it is measuring, which is obvious based on your comments so far. You should search around on this forum a bit for this topic...it's only been discussed ad nausem since about 2001.

 

[1342]

agree to disagree.but thanks for the input and 73s