rfx 75 in cobra 29 ltd

[pumphouse]

From my testing....

RMS watts will push an amp harder then "peak" watts.


For example,

Lets Take two radios on the bench with an amp:

Radio 1 does 6 watts RMS and 35 peak
Radio 2 does 10 watts RMS and 25 peak.

Connect both radios to an amp for example a Dave Made M200 (1) 2290 drv (2) 2879's. Radios were keyed to read 50 watts RMS (adjusted by variable on amp)

Keep your meter on RMS and then you will see that:

The radio that does LESS PEAK watts AND MORE RMS watts will make that amp do MORE RMS watts. Nevermind the "peak" readings. RMS is where its at. If im wrong, someone please prove otherwise.

RMS FORWARD swing is what you are looking for. Thats where the real powers at.

Im not trying to reinvent the wheel. Thats just from my testing on the bench.

 

[DIRTYWHITEBOY]

From my testing....

RMS watts will push an amp harder then "peak" watts.


For example,

Lets Take two radios on the bench with an amp:

Radio 1 does 6 watts RMS and 35 peak
Radio 2 does 10 watts RMS and 25 peak.

Connect both radios to an amp for example a Dave Made M200 (1) 2290 drv (2) 2879's. Radios were keyed to read 50 watts RMS (adjusted by variable on amp)

Keep your meter on RMS and then you will see that:

The radio that does LESS PEAK watts AND MORE RMS watts will make that amp do MORE RMS watts. Nevermind the "peak" readings. RMS is where its at. If im wrong, someone please prove otherwise.

RMS FORWARD swing is what you are looking for. Thats where the real powers at.

Im not trying to reinvent the wheel. Thats just from my testing on the bench.

How are you measuring your "RMS Watts"?

 

[Switch Kit]

From my testing....

RMS watts will push an amp harder then "peak" watts.


For example,

Lets Take two radios on the bench with an amp:

Radio 1 does 6 watts RMS and 35 peak
Radio 2 does 10 watts RMS and 25 peak.

Connect both radios to an amp for example a Dave Made M200 (1) 2290 drv (2) 2879's. Radios were keyed to read 50 watts RMS (adjusted by variable on amp)

Keep your meter on RMS and then you will see that:

The radio that does LESS PEAK watts AND MORE RMS watts will make that amp do MORE RMS watts. Nevermind the "peak" readings. RMS is where its at. If im wrong, someone please prove otherwise.

RMS FORWARD swing is what you are looking for. Thats where the real powers at.

Im not trying to reinvent the wheel. Thats just from my testing on the bench.

Huh ? What kind of meter is this that your using ? ........RMS is RMS and PEP is PEP ........take your pick . Both are real world "readings" a PEP reading DOES NOT make it a lie. (although there is something called splatter/TVI/Harmonics and the false truth of it all)

for those that do not get so deeply involved in these kinds of things , PEP readings comfort "some" given users more then RMS readings do , it's a numbers game. Or it's EGO Radio thing or it tends to sell better , So what ! ? Whatever floats ones boat and keeps them happy with what they have.

Does the average radio/amplifier operator really care that much ? Do they have 10s of thousands of dollars of testing equipment to really know what's going on ? .......I don't think so. Is ballpark or false readings good enough for most weather they believe it or not ? ......I'd like to think so.

I'd bet to say that 3/4s of the radio operating world couldn't or wouldn't be able to handle the truth about what was really going on with there RMS/PEP readings anyway !! It's simply a boom squash syndrome for them and what matters the most for them is that they are having fun with what they are doing. The truth don't matter to them.

I can surely appreciate knowing the differants between RMS and PEP readings , but the bottom line weather true or false , they are both readings. Take your pick. If it has to be as perfect for you as you can get it ? Have at it.

Weak RF output? "Real PEP" is NOT a meter!

 

[W5LZ]

You have to understand what you are measuring, and how. Those Pep watts are instantaneous values, very seldom (never) stay that high for any length of time. So, those values contribute very little to the 'average' power output of a transmitter. That can certainly come in handy at times, but in general, just doesn't mean a lot as far as any 'work' being done. They do 'average out' over time.
If you use a constant, non-varying input to that transmitter, hold that input for a second or two or three, you'll see that RMS and Pep reading the same. It's all in the timing. And 'bigger numbers' of course.
- 'Doc

 

[flush]

Not to hijack but have my opinion on the whole pep vs rms.

So If I have a amp that dk 100w swinging 200w rms or 400pep. It would be better to dk 150w swinging (neg)100w rms but fwd 500pep???

I always thought of PEP as the happy watts. But to get the rms going fwd you were doing something. Such as making your whole signal more powerful including the carrier somewhat? So many theories...

Well I did test a mag 257 against a 2510 once using the fs meter a few feet away.
The 257 (erf2030) was set at 3w swinging 6rms/55 pep.
2510 was set at 3w swinging 15w/45 pep.

The 2510 was noticeably louder and stronger on the meter.


1) I used the term rms as the same as avg however if you get more technical yes there is two different meanings to them.
2) To get the rms/avg forward swing there has to be mods done. Yes you can cut limiters, stretch/open coils(filters) and make a splatter machine. But that's not what is going on in my example. Well not to much.. but thats a whole nother story....

 

[1342]

Not to hijack but have my opinion on the whole pep vs rms.

So If I have a amp that dk 100w swinging 200w rms or 400pep. It would be better to dk 150w swinging (neg)100w rms but fwd 500pep???

I always thought of PEP as the happy watts. But to get the rms going fwd you were doing something. Such as making your whole signal more powerful including the carrier somewhat? So many theories...

Well I did test a mag 257 against a 2510 once using the fs meter a few feet away.
The 257 (erf2030) was set at 3w swinging 6rms/55 pep.
2510 was set at 3w swinging 15w/45 pep.

The 2510 was noticeably louder and stronger on the meter.


1) I used the term rms as the same as avg however if you get more technical yes there is two different meanings to them.
2) To get the rms/avg forward swing there has to be mods done. Yes you can cut limiters, stretch/open coils(filters) and make a splatter machine. But that's not what is going on in my example. Well not to much.. but thats a whole nother story....

great post flush i have argued with techs about this and you just proved my point!you would think of all people that a tech would allready know this but i guess if your buisness is selling radios to truckers and the pep major needle movement is a good sales pitch. thank you.

 

[74IN]

RMS is bunk, no application in AC RF. It's average.

This is all nit-picking.

If they can hear me and I can hear them, who cares.

Otherwise, continue with the bigger dick game.

 

[flush]

Is happy and Dosy watts the same?
I do know that bird 43 is kind of like the Judge. And usually when I'm facing the Judge it's not a happy time. :sad: You know he brings you back to reality.

Ok who had the 140 watt RFX75?

As a side note I did see a rfx75 in a cobra 25. It was amazing to see a little radio do 45rms/100pep!(B43w/pep) Talk about a sleeper!!

I also heard from a little birdy that there is a radio floating around that has 4 of these "big" erf7530s in it doing 400+/pep.

And I thought barefoot was 50w max???

 

[Switch Kit]

I couldn't tell you about Dosy "happy watts" ? but I could tell you about Bird 43P "happy watts" , at least there happy ah ? or does it really matter if it's 45 rms (sad watts ?) or 100 pep "Happy Watts" ? reminds me of centimeters compared to inches , both the same , just a different reading.

Whatever the case may be in Dosy / PDC / Astatic / Bird / ect. ect. ect. The RFX 75s work very well at any "happy" reading you might want to take on them. For those that really seem to think they need to go by RMS readings and it more so floats there boats ? So be it ! If you perfer pep readings as your calling ? So be it !

You can read them anyway you want , in the end , the only thing that really matters to me is that the units work and make a differance on the receiving ends of things.

 

[1342]

Is happy and Dosy watts the same?
I do know that bird 43 is kind of like the Judge. And usually when I'm facing the Judge it's not a happy time. :sad: You know he brings you back to reality.

Ok who had the 140 watt RFX75?

As a side note I did see a rfx75 in a cobra 25. It was amazing to see a little radio do 45rms/100pep!(B43w/pep) Talk about a sleeper!!

I also heard from a little birdy that there is a radio floating around that has 4 of these "big" erf7530s in it doing 400+/pep.

And I thought barefoot was 50w max???

good call i have only seen about three listings for average power on this rfx and they were from 30 to the highest of 60 watts.45 real watts on a cobra 25 is great

 

[Cityboy]

1342 I would say the 30-40w RMS is probably a more honest reading. I have done a couple of these and my "happy" reading Dosy shows around 35-40w RMS at an honest 13.79-80v reading using a Astron VS-35m and my old analog swing meter by Radio shack I purchased 25 yrs ago(also confirmed withing .015v with my Fluke digital). The overflated numbers are being driven by some who are running well above 14.0v and as much as 15.5v in some cases on these readings. Like Switchkit said it is in the person reading the values and the set-up to achieve them. A Bird meter may well be the standard to read some values with validity, but who is to say someone has not gone in and done the own adjustments to any meter to make it read the way you want it to. I have posted on this installation and I have reported honest numbers with running it in a real world situation like a tractor as myself and fellow truck drivers do. The one thing I think is a potential problem with this RFX is heat, both installations showed downward watts on dk if you talk for extended time periods. Therefore I have installed a 40mm fan just underneath the RFX( if you push RFX up towards the top cover and install it leaves room for a 40mm fan) and has really done a great job of dissapating the heat. I also have started installing a 820pF dipped mica cap at C8 in the future ones I install. Good luck, if you have any questions just pm me. I also added coil around the power wires of the fan going to the terminals in the radio to get rid of any potential fan whine.

 

[1342]

1342 I would say the 30-40w RMS is probably a more honest reading. I have done a couple of these and my "happy" reading Dosy shows around 35-40w RMS at an honest 13.79-80v reading using a Astron VS-35m and my old analog swing meter by Radio shack I purchased 25 yrs ago(also confirmed withing .015v with my Fluke digital). The overflated numbers are being driven by some who are running well above 14.0v and as much as 15.5v in some cases on these readings. Like Switchkit said it is in the person reading the values and the set-up to achieve them. A Bird meter may well be the standard to read some values with validity, but who is to say someone has not gone in and done the own adjustments to any meter to make it read the way you want it to. I have posted on this installation and I have reported honest numbers with running it in a real world situation like a tractor as myself and fellow truck drivers do. The one thing I think is a potential problem with this RFX is heat, both installations showed downward watts on dk if you talk for extended time periods. Therefore I have installed a 40mm fan just underneath the RFX( if you push RFX up towards the top cover and install it leaves room for a 40mm fan) and has really done a great job of dissapating the heat. I also have started installing a 820pF dipped mica cap at C8 in the future ones I install. Good luck, if you have any questions just pm me. I also added coil around the power wires of the fan going to the terminals in the radio to get rid of any potential fan whine.

great post city boy that is what i figured on the output but if you say that to most people out here they dont like it the facts are clear for me this is not a 100-140 watt transistor!the only transistor i know of around that # would be the 2sc2879 and that mosfet is no 2sc2879 but anyway i was interested in installing 1 of these in my old magnum 257.no one seems to know if this will work and there is minimal information on any good mods for this smt board besides the zener resistor mod for am which works quite well but the ssb output and modulation are nothing to write home about.i did manage to jumper the collectors to straight 14 volts which did help ssb by about 5-6 watts.this radio on its best day sqeezed out about 30 watts after a match set of 2312s and a 2312 as the driver from rf parts but those went a few years back and now the radio has mis matched 2312s the crappy ones that you get when you order like 10 at a time.back in the day i would order lots of stuff from them and would request high power lots of these matched transistors and they performed superb.i love this radio but it at least needs more audio!

 

[Cityboy]

1342 if you have a question about whether you can install on your Magnum radio call up Al at Sparky's and he should be able to answer your question. If not go to his web site and join up on the section of ask the tech and post the question. He will or someone will harp in and give you an answer; I have heard several wanting to install these on similiar radios and it seems no one seems to have a clear answer. But these replacement finals were actually made to replace a Magnum final section, so that being said it possible to make it work. The problem is not many of us really have the experience on a SMT board and the expensive equipment( a proper desoldering station and soldering station $600-$1300) that radio shop has. There is a guy that could definitely answer your question which is Rick Jackson from England. He has a web site I think under Euroradio or something like that. You can join his forum and ask the question; he knows alot about almost any radio and actually designs and redesigns board configuration like yours. He has posted several things for cbtricks.com for all of us to use. Those unreal numbers you are hearing about are just that about the RFX, so realistically someone using that set-up in most radios is going to see a dk=12-15w, and around 72-80w pep at an average 13.80v. If you ramp it up you could definitely see more, because I have turned my Astron to just a hair above 15v and it really did swing, but I did not take a reading because I was afraid of damage. I figured that for something that was say $43 and I got 80w pep and 2-3 hours of my time, then I was happy enough. Good luck on your Magnum.

 

[pumphouse]

Not to hijack but have my opinion on the whole pep vs rms.

So If I have a amp that dk 100w swinging 200w rms or 400pep. It would be better to dk 150w swinging (neg)100w rms but fwd 500pep???

I always thought of PEP as the happy watts. But to get the rms going fwd you were doing something. Such as making your whole signal more powerful including the carrier somewhat? So many theories...

Well I did test a mag 257 against a 2510 once using the fs meter a few feet away.
The 257 (erf2030) was set at 3w swinging 6rms/55 pep.
2510 was set at 3w swinging 15w/45 pep.

The 2510 was noticeably louder and stronger on the meter.


1) I used the term rms as the same as avg however if you get more technical yes there is two different meanings to them.
2) To get the rms/avg forward swing there has to be mods done. Yes you can cut limiters, stretch/open coils(filters) and make a splatter machine. But that's not what is going on in my example. Well not to much.. but thats a whole nother story....

Great post x2.

Exactly what I was trying to get at. If given a choice between the two radios, The peak meter worshipers would take the 257 as described above because "it does more peak watts" LOL! They would think...hmmmmmmmmm the 257 has 10 more peak watts therefore its "stronger". They are mistaken. In the serenio described above, the 2510 is the stronger radio NOT because it has 10 less peak watts, because it has MORE RMS watts. (9) more RMS watts to be exact.

DONT BE FOOLED BY PEAK WATTS. RMS FORWARD SWINGING WATTS IS WHERE ITS AT.


How many people do you know that has RMS watts backswing on their setups when they audio? Not the way to go.

How many people do you know that are swingin FORWARD on RMS when they audio?
They did it right.

Okay wont bring this up again. But the rfx 75 in the cobra does have some nice forward swingin RMS watts.

They should put that question on the next ham radio exam. It would go something like this:

1. Which is the "stronger radio"?
Radio 1 has a dead key of 3 watts RMS swing 6 watts RMS with a 55 watt peak.
Radio 2 has a dead key of 3 watts RMS swing 15 watts RMS with a 45 watt peak.

Wonder how many "HAMS" would answer that question correctly?

Like prime minister said in one of his videogates..... hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.

Anyone wanna take a stab at that question and explain your answer? Hmmmmmmmmmmmm

 

[1342]

Great post x2.

Exactly what I was trying to get at. If given a choice between the two radios, The peak meter worshipers would take the 257 as described above because "it does more peak watts" LOL! They would think...hmmmmmmmmm the 257 has 10 more peak watts therefore its "stronger". They are mistaken. In the serenio described above, the 2510 is the stronger radio NOT because it has 10 less peak watts, because it has MORE RMS watts. (9) more RMS watts to be exact.

DONT BE FOOLED BY PEAK WATTS. RMS FORWARD SWINGING WATTS IS WHERE ITS AT.


How many people do you know that has RMS watts backswing on their setups when they audio? Not the way to go.

How many people do you know that are swingin FORWARD on RMS when they audio?
They did it right.

Okay wont bring this up again. But the rfx 75 in the cobra does have some nice forward swingin RMS watts.

They should put that question on the next ham radio exam. It would go something like this:

1. Which is the "stronger radio"?
Radio 1 has a dead key of 3 watts RMS swing 6 watts RMS with a 55 watt peak.
Radio 2 has a dead key of 3 watts RMS swing 15 watts RMS with a 45 watt peak.

Wonder how many "HAMS" would answer that question correctly?

Like prime minister said in one of his videogates..... hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.

Anyone wanna take a stab at that question and explain your answer? Hmmmmmmmmmmmm

thats it pumphouse no pep on my bench and if anyone would like to do a shootout with me -there pep watts verse my average watts they will be disapointed but i am willing!