KL203 Amp

[rabbiporkchop]

Receive sensitivity hasn't been an issue for years. I've tested countless CBs on Marconi test gear including models that have a reputation of being deaf and every single one of them has been able to reproduce a10dB SINAD at -120dBm. -120dBm is the level used for testing receivers on CB because it is the noise floor for 11m of anywhere on planet earth due to the fact that is what the galactic noise floor is for 11m.

This is why I always find it incredulous that people send off their rigs for tweaking. The rig isn't the problem, their crappy antenna installation is.

It's always been an issue on 10 meter export equipment. There are very few decent "truck accessible technicians". Another one just died recently. Very few drivers are using stock unmodified 11 meter radios, although those are often the ones that hear me the furthest.

 

[M0GVZ]

It's always been an issue on 10 meter export equipment.

Very few drivers are using stock unmodified 11 meter radios, although those are often the ones that hear me the furthest.[/QUOTE]

Really it hasn't been an issue on 10m "export radios" either. Difference between my point of view and most you've heard is mine is based on proper test methodology using proper test equipment and not just random anecdotal evidence usually involving someone saying they're deaf and not even considering its their shitty antenna installation.

Very few drivers are using stock unmodified 11 meter radios, although those are often the ones that hear me the furthest.

And that's the problem. More and more people whack up the power to be heard until everyone has to run 100W just to be heard at the end of the street.

 

[rabbiporkchop]

And that's the problem. More and more people whack up the power to be heard until everyone has to run 100W just to be heard at the end of the street.

Agreed. Unfortunately, 95% of "radio technicians" think it is possible to achieve the above with 150% negative modulation while still maintaining decent receive.

 

[LeapFrog]

Agreed. Unfortunately, 95% of "radio technicians" think it is possible to achieve the above with 150% negative modulation while still maintaining decent receive.

Care to expand your statement?
It almost reads as if you're saying that TX characteristics of a radio somehow affect the receive performance (in/of that same radio).

If you mean to say over-mod sounds nasty in a standard receiver (and anything over 100% Neg), then I agree with you.

If you are talking about receive sensitivity.. I can't comment

 

[rabbiporkchop]

Care to expand your statement?
It almost reads as if you're saying that TX characteristics of a radio somehow affect the receive performance (in/of that same radio).

If you mean to say over-mod sounds nasty in a standard receiver (and anything over 100% Neg), then I agree with you.

If you are talking about receive sensitivity.. I can't comment

Butchering transmit also butchers receive. The two go hand in hand.

 

[LeapFrog]

Butchering transmit also butchers receive. The two go hand in hand.

For the receiving radio?

I can destroy the TX quality of my radio and leave the RX alone, i'm not talking about being on-frequency.. So I guess you mean, the radio that has to hear the nasty transmit audio?

Take care, 73.

 

[rabbiporkchop]

For the receiving radio?

I can destroy the TX quality of my radio and leave the RX alone, i'm not talking about being on-frequency.. So I guess you mean, the radio that has to hear the nasty transmit audio?

Take care, 73.

It has nothing to do with being on frequency or not. All these circuits are interrelated and tampering with one has an effect on the other. Changing audio characteristics of your transmit changes the same characteristics of your receive.

 

[LeapFrog]

It has nothing to do with being on frequency or not. All these circuits are interrelated and tampering with one has an effect on the other. Changing audio characteristics of your transmit changes the same characteristics of your receive.

I'm talking about adjustment points, not audio circuit modifications.
Glad that's cleared up, I should have re-read the entire thread.

 

[543_Dallas]

There are cases where a modification to the transmitter can effect the receiver. To make a generalized statement about all transmit mods on all ratios effecting the receiver....well it's just not accurate.

I would like to know how one measures negative modulation percentage over 100%.

 

[rabbiporkchop]

There are cases where a modification to the transmitter can effect the receiver. To make a generalized statement about all transmit mods on all ratios effecting the receiver....well it's just not accurate.

I would like to know how one measures negative modulation percentage over 100%.

By using a meter and not having an oscilloscope. We're talking about typical truck stop hack jobs.

 

[543_Dallas]

By using a meter and not having an oscilloscope. We're talking about typical truck stop hack jobs.

Even with a scope how do you measure negative modulation percentage past 100%?

Agreed. Unfortunately, 95% of "radio technicians" think it is possible to achieve the above with 150% negative modulation while still maintaining decent receive.

This statement is what brought on the question. I'm starting to question the statistics and specs that you post in your ramblings.

 

[LeapFrog]

Gentleman,
I've read some replies incorrectly, so please excuse me for that.

543 Dallas, I agree with you about the statement, that is what brought on the question, RabbiPorkChop. It was a very generalized statement about percentages affecting other aspects of the radio (to a noticeable degree), It is not true (not specific enough).
I'm not yearning for a battle of wits... But the statement made me wonder, wtf!

Perhaps I am ignorant of some aspect of my tool's capability. If this statement is true, please inform or enlighten a brother with some details regarding the reading of (Negative) modulation peaks beyond 100%, without a "blind approximation" accounted for; using an analog oscilloscope?


P.S. I was wondering how touching a modulation adjustment point (variable resistor) was going to affect my receive audio.. Now I see, we can be talking about many things at once....

 

[rabbiporkchop]

Even with a scope how do you measure negative modulation percentage past 100%?



This statement is what brought on the question. I'm starting to question the statistics and specs that you post in your ramblings.

since 95% of "radio technicians"
( and I use that term loosely ) from coast to coast Produce results virtually identical to this

without having a clue of what they are doing, and the receive is terrible on those particular radios it would be logical to conclude that because they have no clue about a transmitter how could they possibly have a clue about a receiver?

 

[LeapFrog]

since 95% of "radio technicians"
( and I use that term loosely ) from coast to coast Produce results virtually identical to this

without having a clue of what they are doing, and the receive is terrible on those particular radios it would be logical to conclude that because they have no clue about a transmitter how could they possibly have a clue about a receiver?

No, I asked how you can claim to measure the neg's beyond 100% without making an extremely limited approximation ((guessing)).

But yeah, if they have results like that for TX, we could assume they would "fubar-whack" the RX end. That's true enough.

Guess I read your post wrong.
That said, if they left the receiver alone, factory it can't be too far off, use-able at least..
Maybe they are using uncalibrated equipment or don't understand the alignment process, one is left to wonder...

Those guys in the group you mention aren't changing the audio section caps; unless they read it online somewhere... Even that won't wreck RX in the AM only radios i'm thinking of.

More likely they snip the diode or pull the TR('s), not measuring anything, most of the guys doing work like that in the picture, they can solder and have seen some tricks and copy it.

They won't know how to align the radio to spec, they may not have the equipment to do it or they don't understand many technical details beyond that they can identify components and google the CBsecrets to find what to clip.

It's not a science you know, making a radio "swing". Not to those guys, they are delusional, completely and utterly obsessed with the watt meter. Now if they can tell you peak to peak voltages and measure everything, and they understand amplitude modulation to a degree. Then it can be scientific, but these swing thing tunes are RARELY in a "clean manner", when they are done correct; You've found a Technician with some understanding.

IMO "Tech Work" like in the picture above is done by guys that are not the type to be able to look at a schematic (and a few datasheets) and envision a modification purely from experience or understanding; simply put, they are not versed enough and lack understanding. (Unless they think a square wave is good, then they are still delusional imho, harmonics and distortion should not be the goal)

Surely I am no expert, far be it for me to critique others' work; but you really can see who has no clue what-so-ever, and someone who at least knows a little bit, and then you see some really impressive "technicians", often times they are older Amateur operators.

 

[rabbiporkchop]

No, I asked how you can claim to measure the neg's beyond 100% without making an extremely limited approximation ((guessing)).

But yeah, if they have results like that for TX, we could assume they would "fubar-whack" the RX end. That's true enough.

Guess I read your post wrong.
That said, if they left the receiver alone, factory it can't be too far off, use-able at least..
Maybe they are using uncalibrated equipment or don't understand the alignment process, one is left to wonder...

These "clip n run" guys aren't changing the audio section caps; unless they read it online somewhere... Even that won't wreck RX in the AM only radios i'm thinking of.

More likely they snip the diode or pull the TR('s), not measuring anything, most of the guys doing work like that in the picture

They won't know how to align the radio to spec, they may not have the equipment to do it or they don't understand many technical details beyond that they can identify components and google the CBsecrets to find what to clip.

It's not a science you know, making a radio "swing". Not to those guys, they are delusional, completely and utterly obsessed with the watt meter. Now if they can tell you peak to peak voltages and measure everything, and they understand amplitude modulation to a degree. Then it can be scientific, but these swing thing tunes are RARELY in a "clean manner", when they are done correct; You've found a Technician with some understanding.

IMO "Tech Work" like in the picture above is done by guys that are not the type to be able to look at a schematic (and a few datasheets) and envision a modification purely from experience or understanding; simply put, they are not versed enough and lack understanding. (Unless they think a square wave is good, then they are still delusional imho, harmonics and distortion should not be the goal)

Surely I am no expert, far be it for me to critique others' work; but you really can see who has no clue what-so-ever, and someone who at least knows a little bit, and then you see some really impressive "technicians", often times they are older Amateur operators.

I was speculating on the percentage of modulation and threw that number out there. not scientific by any means