So i need a solid answer here. On the old cobra 148gtl radios, 5 pin side mic made in Taiwan, if i remove r131 does it disable the modulation limiter completely, basically same as removing the transistor. Or does it keep the modulation limiter function working, with just a boost in am modulation?
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Cobra 148gtl r131 removal?
- Thread starter groundwire
- Start date
Removing R131 disables TR26, which is the AM mod limiter transistor. Changing the value of R131 will allow the AMC to function, but across a wider range.
~Cheers~
~Cheers~
@Handy Andy , save you the trouble...
@groundwire , it isn't that simple
"
Greetings!
No, TR34 ALC sense/amp connects to TR25 AMC/ALC amp.
R131 affects TR26 AMC sense/amp.
<Why? This is where it gets long winded. Readers are invited to
comment...>
The bad thing about TR26, is the inherent fault of placing the emitter
on the AM regulator output line to the finals, audio is always applied
to the emitter versus using the base and running it as a limiter
versus a regulator in itself when the radios' in AM mode.
It conducts when the base voltage reference done by R131 and R130
affects the emitter voltage off the sense line from AM regualtor. It
begins to begins to fall when audio is applied. Falls too far, the
emitter of TR26 is at a lower reference voltage than the base, and
begins to conduct, pulling TR25s' base low and this forces TR25 to
work. By sensing the dropping DC voltage, this circuit operates to
prevent negative peaks from forcing cuttoff at the Finals. The forward
swing is allowed, but C109 acts as a peak/hold filter that recovers
thru a series of set limiter resistors.
It's a cascade effect. Under SSB mode, this automatically biases off
TR26 [straight 12V reverse biases the emitter but the collector
acheives a high impedance 8 volts to provide a reference to TR25 due
to what R131 and R130, along with R129/R128 provide to the sense
line].
In SSB, TR34 runs TR25 instead. TR25 conducts when it's base voltage
is pulled below the reference voltage R129/R128 gives from the line
shared by the collectors of TR26 and TR34.
Due to the biasing of the base of TR26, the collector output is a
steady voltage, but at a high-impedance set by R130 and R131 and
TR25's R128/R129.
A small change in voltage on TR34's collector affects the collector of
TR26 and the base of TR25, and TR25 acts like a switch and changes
it's state [due to the bias reference of R129/R128] and a capacitor
10uF acts like a filter and also something to work against when the
charge removed from C109 is recovered due to biasing
R128/R129/R130/R131 provide. That in turn forces the AF limiter TR24
to conduct.
In AM mode, 8 volts constant is applied to the emitter of TR34, so any
sensing of envelope exceeding a refrence TR34 wants to conduct on, it
can't, no current flows because the emitter is reverse biased.
Whats a pain, is you'd think that simply removing TR26 would take care
of the problem right? Alas, it's not that way. A voltage needs to be
present to make TR25 remain off, and because of the 8 volt constant
used to regulate the base of TR26, this is where the ALC works against
a set value, and TR25 remains off until TR24 pulls this reference
voltage low enough to force TR24 to conduct and limit audio. R128
offers high-impedance to TR34, but will always have a voltage present
on it due to the forward voltage drop of TR26's collector to base and
R130. So, it will always provide a voltage sense and is why TR26 needs
to remain there. The collector to base drop is only .7 volts, but
R130, along with R128/R129, gives TR34's sense line some reference,
only at a high impedance, and a slight change of this line and TR25
acts like it did before. R128 drains off R129's reference from 8 volts
constant.
[condensed from my notes over a Cobra 148 - due to labeling and
additional changes, some parts noted above may vary from 148 to 148 ST
models.]
There's ways around this of course, but TR24 being removed or R131, is
the down and dirty way, except removing TR24 is inherently affecting
both modes and is a lot dirtier in results.
Removing R131 takes care of the 8 volt reference TR26 needs, it then
remains conducting due to R130 keeping the base reference to ground,
but keeping the emitter effectively "off" all the time - no matter
what voltage may be present at the emitter. The radio is not capable
of dropping that much in AM regulation voltage on the emitter to go
below base reference R130 has.
But, due to the bleedoff of R129 from the base of TR25 and R128 and
forward voltage drop and bias of collector to base of TR26 and R130,
this reference voltage is close to, but not quite at the same voltage
had R131 been in place.
Hopefully I have this right...;-)
~Handy Andy
@groundwire , it isn't that simple
"
Greetings!
No, TR34 ALC sense/amp connects to TR25 AMC/ALC amp.
R131 affects TR26 AMC sense/amp.
<Why? This is where it gets long winded. Readers are invited to
comment...>
The bad thing about TR26, is the inherent fault of placing the emitter
on the AM regulator output line to the finals, audio is always applied
to the emitter versus using the base and running it as a limiter
versus a regulator in itself when the radios' in AM mode.
It conducts when the base voltage reference done by R131 and R130
affects the emitter voltage off the sense line from AM regualtor. It
begins to begins to fall when audio is applied. Falls too far, the
emitter of TR26 is at a lower reference voltage than the base, and
begins to conduct, pulling TR25s' base low and this forces TR25 to
work. By sensing the dropping DC voltage, this circuit operates to
prevent negative peaks from forcing cuttoff at the Finals. The forward
swing is allowed, but C109 acts as a peak/hold filter that recovers
thru a series of set limiter resistors.
It's a cascade effect. Under SSB mode, this automatically biases off
TR26 [straight 12V reverse biases the emitter but the collector
acheives a high impedance 8 volts to provide a reference to TR25 due
to what R131 and R130, along with R129/R128 provide to the sense
line].
In SSB, TR34 runs TR25 instead. TR25 conducts when it's base voltage
is pulled below the reference voltage R129/R128 gives from the line
shared by the collectors of TR26 and TR34.
Due to the biasing of the base of TR26, the collector output is a
steady voltage, but at a high-impedance set by R130 and R131 and
TR25's R128/R129.
A small change in voltage on TR34's collector affects the collector of
TR26 and the base of TR25, and TR25 acts like a switch and changes
it's state [due to the bias reference of R129/R128] and a capacitor
10uF acts like a filter and also something to work against when the
charge removed from C109 is recovered due to biasing
R128/R129/R130/R131 provide. That in turn forces the AF limiter TR24
to conduct.
In AM mode, 8 volts constant is applied to the emitter of TR34, so any
sensing of envelope exceeding a refrence TR34 wants to conduct on, it
can't, no current flows because the emitter is reverse biased.
Whats a pain, is you'd think that simply removing TR26 would take care
of the problem right? Alas, it's not that way. A voltage needs to be
present to make TR25 remain off, and because of the 8 volt constant
used to regulate the base of TR26, this is where the ALC works against
a set value, and TR25 remains off until TR24 pulls this reference
voltage low enough to force TR24 to conduct and limit audio. R128
offers high-impedance to TR34, but will always have a voltage present
on it due to the forward voltage drop of TR26's collector to base and
R130. So, it will always provide a voltage sense and is why TR26 needs
to remain there. The collector to base drop is only .7 volts, but
R130, along with R128/R129, gives TR34's sense line some reference,
only at a high impedance, and a slight change of this line and TR25
acts like it did before. R128 drains off R129's reference from 8 volts
constant.
[condensed from my notes over a Cobra 148 - due to labeling and
additional changes, some parts noted above may vary from 148 to 148 ST
models.]
There's ways around this of course, but TR24 being removed or R131, is
the down and dirty way, except removing TR24 is inherently affecting
both modes and is a lot dirtier in results.
Removing R131 takes care of the 8 volt reference TR26 needs, it then
remains conducting due to R130 keeping the base reference to ground,
but keeping the emitter effectively "off" all the time - no matter
what voltage may be present at the emitter. The radio is not capable
of dropping that much in AM regulation voltage on the emitter to go
below base reference R130 has.
But, due to the bleedoff of R129 from the base of TR25 and R128 and
forward voltage drop and bias of collector to base of TR26 and R130,
this reference voltage is close to, but not quite at the same voltage
had R131 been in place.
Hopefully I have this right...;-)
~Handy Andy
Awright..
What you want is to get full audio drive to the AM modulator.
What you don't want is to disable the sideband limiter, the ALC. Bad juju if you want to use SSB.
I would suggest removing TR26, type 2SC945. This is the transistor you meant to shut down by pulling R131. The bonus is that you can insert the transistor you just removed into the empty spot where someone has already removed TR24. That transistor is needed for both AM and SSB limiting. SSB will sound a LOT better with VR11 set to hold the sideband level below the distortion point. VR11 will only make a difference when TR24 is properly in place.
TR24 is the frequent target of internet "free advice" and will open up the AM if pulled. Totally screws up sideband transmit audio quality.
The Cliff Notes version.
73
What you want is to get full audio drive to the AM modulator.
What you don't want is to disable the sideband limiter, the ALC. Bad juju if you want to use SSB.
I would suggest removing TR26, type 2SC945. This is the transistor you meant to shut down by pulling R131. The bonus is that you can insert the transistor you just removed into the empty spot where someone has already removed TR24. That transistor is needed for both AM and SSB limiting. SSB will sound a LOT better with VR11 set to hold the sideband level below the distortion point. VR11 will only make a difference when TR24 is properly in place.
TR24 is the frequent target of internet "free advice" and will open up the AM if pulled. Totally screws up sideband transmit audio quality.
The Cliff Notes version.
73
Hmmm, im gonna just leave it stock then, screw it. I will just cram audio into it with an amplified mic and it is what it is. I Scored a virgin completely stock untouched inside radio from a storage sale and it looks 9.5 out of 10. Amazing. Wish it just had the standard amc pot . Oh well.
Wow - talk about a blast from the past...
SIGH...Thanks guys - the Silver in my hair is showing...
Removing R131 - not unlike the "freeway" for AM side, but the BANE for those using SSB.
R131 - review...
You want to control MODULATION...
OR...
Do you want to control ENVELOPE?
Modulation - AMC = R131 and Associated from AM Regulator
Envelope - ALC - SSB = R161 and ASSOCIATED SSB stuff
Everything? R127 - ONLY to an extent...you LOWER it's value - changes all parameters...
Will discuss later - have to fix some XYL's issues....
SIGH...Thanks guys - the Silver in my hair is showing...
Removing R131 - not unlike the "freeway" for AM side, but the BANE for those using SSB.
R131 - review...
You want to control MODULATION...
OR...
Do you want to control ENVELOPE?
Modulation - AMC = R131 and Associated from AM Regulator
Envelope - ALC - SSB = R161 and ASSOCIATED SSB stuff
Everything? R127 - ONLY to an extent...you LOWER it's value - changes all parameters...
Will discuss later - have to fix some XYL's issues....
Wow - talk about a blast from the past...
SIGH...Thanks guys - the Silver in my hair is showing...
Removing R131 - not unlike the "freeway" for AM side, but the BANE for those using SSB.
R131 - review...
View attachment 37620
You want to control MODULATION...
OR...
Do you want to control ENVELOPE?
Modulation - AMC = R131 and Associated from AM Regulator
Envelope - ALC - SSB = R161 and ASSOCIATED SSB stuff
Everything? R127 - ONLY to an extent...you LOWER it's value - changes all parameters...
Will discuss later - have to fix some XYL's issues....
Don’t feel bad buddy..I’m 47 and got a head FULL of grey hair.
Ok, considering I was interrupted - Hi Hon... IF you're listening...
You just have to know how NPN and PNP's work but the main premise is
Sadly this confuses a lot of people - for there are really two "senses" the radio uses to control how much Modulation goes into the signal - going out...
One sense is used for each mode, but one of those senses can "leak" into the other when you least expect it.
It's why there arrows and hi-lites and coming soon, KC's...
Kidding aside...
Ok, so removing the R131, then "disables" the AMC - then why does the radio seem to want to still limit modulation...?
Good question, remember the References above to NPN and PNP?
You have to know how current can flow thru the transistors even when it should not be able to.
How?
Well, NPN needs a Positive presence on the Base of the part to even be able to allow current to flow.
But a PNP will always allow current to flow thru until the Base has a positive presence on it - to turn off the part.
Now - knowing that the PNP being placed in the circuit like it is, can also affect the Limiter...
How, by current flow...the Thing is set up to INVERT results too...
Remember that TR34 is set to be turned off because it's Emitter is biased to a higher voltage than usual, but not as high as a Collector can be - so TR34 is reverse Biased due to the Positive aspect of the Emitter leg.
ALC would work, if the Emitter was LESS positive than the Collector, or in the NPN terms, it was MORE NEGATIVE than the BASE lead - meaning it can turn on when Positive Presence at the Base is GREATER than the Positive Presence in the Emitter.
So, since the TR34 is a NPN
So what does this mean?
Although relatively few would care to even read this post this far (Thank you) it does serve to mention whether incidental or not, the action that TR34 and TR25 take in regards to SSB mode, can also protect the AM mode from CATASTROPHIC events like overdriven modulation - like; if you have a really bad day when it comes to tune ups.
You can observe this effect by turning the potentiometer used to offset the ALC sense, on a stock 148 GTL radio while in AM mode - and whistle into the mike and listen for the results in a Monitor radio (using a dummy load of course).as you adjust. You'll hear it "Clamp" more than limit - because of the conduction threshold breech.
This is also why I mentioned the R127 aspect, the 1 Meg resistor (Pun intended). Playing with this value it changes everything when it comes to activity and aggressive behavior of the Limiter - you lower the Resistor value of R127 into say 560 ohms - you have SOME control of Limiter but not a lot.
So to answer your question - no - Removing R131 disables AMC but not the Limiter - too many other things affect the Limiter - up to and including Noise Abatement - by forcing the Limiter to "on" thru the use of D59 to force it on while in Receive mode.
The other Answer to the question is Yes, it disables the AMC side for AM mode because it has nothing to "reference" as a mid-point for the limiter to even work so it doesn't do much then except sit there - until you are in either SSB mode or RX and listening in...
If you remove TR24 as many do, you will also hear of issues like noisy receive and poor performance and Garbled transmissions caused by overdriven mikes and noisy ignition systems and other nonsense.
So, you asked a two edged sword of a question - first to disable the limiter by removing R131 and then to ask if it keeps the limiter still working; the first one does, the latter? No - so the best advice is to leave TR24 in, AND remove R131 if you need that AM "boost". The radio will last longer and your ears will echo the sentiment by saying thank you - everything else is, in-between and you are left to discover those paths as you see fit.
So- sorry for this long road, but you have to know for the legacy of events leading up to the radios we have now that use this method of detection and amplification for Limiter reaction - sorry to use all those "-ions" - but as we have progressed, some simple sense circuits are still used today in many of the most popular radios - from Stryker, Any Tone, and Cobra for starters
You just have to know how NPN and PNP's work but the main premise is
- Removing R131 - you've disabled the AMC side of things...
- The "Mid point" TR26 would be set for - is now sent to Ground- it has nothing to "reference".
- Although a Good Argument would be that the Positive presence and the difference between the Positive Of the Collector and the negative of the Emitter - allow power that can influence limiter action flow thru self biasing...
- This possibility is from the amount of difference the Sense lead sinks current from the PNP - being biased slightly positive with 33K and sense lead impedance of 15K and a 1Meg resistor placed across this line to ground. But when it does so, the level of power to sink thru TR26 the AM Regulator has be greater than the Positive presenceTR25 has available to send to it thru TR26's Collector - (Not likely due to DC bias present back at the AM Regulator to restore and essentially rest the Limiter back to normal.) I'm not saying it isn't possible but certain conditions have to be met to make the process work
- To a point you'd be correct - also understand too, that the amps used in the 148GTL are active devices and are even kept on when in Receive mode to quench noise in the mic amp circuit
- Changing R131 and R130 "values" sets how the trigger that makes the Limiter act...
- Lowering R130 to R131 (changing the Ratio) - Desensitizes the AMC balance, less energy to sense.
- Removing R131 - takes away the ability to keep TR26 on, which it would be normally - as in - all the time - sending it's output thru to TR25 - the PNP.
- R131 in a way, let's TR26 "Valve" the amount of Modulation seen by the PNP - make R130 equal to it (R131's value) makes TR26 operate more in Class A - making it act more like a compressor.
- AMC only works on AM mode because - all the DC voltage sent to it from SSB modes - the Sense line consisting of R166 and R165 - reverses/inhibits any modulation effect - TR 26 is reverse biased - unable to provide any form of control.
- ALC on the other hand - uses the MODE switch voltage to bias off - or pinch off any level of control - but it still can affect AMC, by proximity to the Limiter, in the daisy chain of parts the PNP resides with - it's the last thing the AM - side of Modulation goes thru, but it's the ONLY thing the Limiter sees...
- Because of the ALC sense control is supposed to work in SSB modes - the means used to turn off this sense "switch" is by lowering the POTENTIAL difference between the Collector and Emitter voltage potential - the Emitter is powered thru a Diode and a current limiting resistor - into being unable to amplify simply by less energy potential between the Collector and Emitter legs when the AM mode is selected
Sadly this confuses a lot of people - for there are really two "senses" the radio uses to control how much Modulation goes into the signal - going out...
One sense is used for each mode, but one of those senses can "leak" into the other when you least expect it.
It's why there arrows and hi-lites and coming soon, KC's...
Kidding aside...
Ok, so removing the R131, then "disables" the AMC - then why does the radio seem to want to still limit modulation...?
Good question, remember the References above to NPN and PNP?
You have to know how current can flow thru the transistors even when it should not be able to.
How?
Well, NPN needs a Positive presence on the Base of the part to even be able to allow current to flow.
Now - knowing that the PNP being placed in the circuit like it is, can also affect the Limiter...
How, by current flow...the Thing is set up to INVERT results too...
ALC would work, if the Emitter was LESS positive than the Collector, or in the NPN terms, it was MORE NEGATIVE than the BASE lead - meaning it can turn on when Positive Presence at the Base is GREATER than the Positive Presence in the Emitter.
So, since the TR34 is a NPN
- this means that a Positive Presence on the Transistors' BASE
- therefore accepts current flow from the Positive Emitter of TR25 thru the Negative Junction of it's BASE on TR25 into TR34
When you turn down the ALC adjust, by lowering the potentiometers effective resistance- if it's Greater than the Emitter potential - current can flow
- this also means that the Collector can then RECEIVE power because it's junction to the BASE is now more positive than the Positive Presence that TR25 that PNP, has- therefore accepts current flow from the Positive Emitter of TR25 thru the Negative Junction of it's BASE on TR25 into TR34
- even though the Emitter of TR24 is (Supposed) biased off.
- TR34 sends power thru it's own Positive Junction of the Base (it's RF sense lead is being rectified) and the Coil used to ground the Base Lead can also put it into Class C and turn on TR34 sending power to and thru into the Emitter even from the Collector- pulling power from TR25 and putting it into conduction because of the Difference potentials between the 8 Volts and the RF voltage presence being sensed at the Base of TR34, a simple low-power NPN amp.
- you affect the Emitter power difference
- TR34 can turn on quickly and stay on as long as the differences in RF power and the DC bias voltage used to turn it off are great enough to keep the part in forward biased mode and still conduct even when biased
- TR34 can turn on quickly and stay on as long as the differences in RF power and the DC bias voltage used to turn it off are great enough to keep the part in forward biased mode and still conduct even when biased
- because you've defeated the Bias presence by trimming it out
So what does this mean?
Although relatively few would care to even read this post this far (Thank you) it does serve to mention whether incidental or not, the action that TR34 and TR25 take in regards to SSB mode, can also protect the AM mode from CATASTROPHIC events like overdriven modulation - like; if you have a really bad day when it comes to tune ups.
You can observe this effect by turning the potentiometer used to offset the ALC sense, on a stock 148 GTL radio while in AM mode - and whistle into the mike and listen for the results in a Monitor radio (using a dummy load of course).as you adjust. You'll hear it "Clamp" more than limit - because of the conduction threshold breech.
This is also why I mentioned the R127 aspect, the 1 Meg resistor (Pun intended). Playing with this value it changes everything when it comes to activity and aggressive behavior of the Limiter - you lower the Resistor value of R127 into say 560 ohms - you have SOME control of Limiter but not a lot.
- because the effect the resistor does have in the SENSE line output of the ALC circuit from TR34 and the Output level of TR26 being your AMC amp and your R131.
- it can affect the "attack timing" as well as the sensitivity and overall effect of the affect that the AMC or ALC sense will exhibit on the Limiter.
- it can affect the "attack timing" as well as the sensitivity and overall effect of the affect that the AMC or ALC sense will exhibit on the Limiter.
So to answer your question - no - Removing R131 disables AMC but not the Limiter - too many other things affect the Limiter - up to and including Noise Abatement - by forcing the Limiter to "on" thru the use of D59 to force it on while in Receive mode.
The other Answer to the question is Yes, it disables the AMC side for AM mode because it has nothing to "reference" as a mid-point for the limiter to even work so it doesn't do much then except sit there - until you are in either SSB mode or RX and listening in...
If you remove TR24 as many do, you will also hear of issues like noisy receive and poor performance and Garbled transmissions caused by overdriven mikes and noisy ignition systems and other nonsense.
So, you asked a two edged sword of a question - first to disable the limiter by removing R131 and then to ask if it keeps the limiter still working; the first one does, the latter? No - so the best advice is to leave TR24 in, AND remove R131 if you need that AM "boost". The radio will last longer and your ears will echo the sentiment by saying thank you - everything else is, in-between and you are left to discover those paths as you see fit.
So- sorry for this long road, but you have to know for the legacy of events leading up to the radios we have now that use this method of detection and amplification for Limiter reaction - sorry to use all those "-ions" - but as we have progressed, some simple sense circuits are still used today in many of the most popular radios - from Stryker, Any Tone, and Cobra for starters
Last edited:
I guess I didn't answer your question...
Don't take this as a flame, because it's not - this is also trying to address an issue that has come up before...
The only thing I left out of this paragraph was "But not the Limiter for SSB, that being ALC"
I thought I had answered that in the next paragraph afterwards but I left out something you didn't know because I didn't put it in there - I presumed you knew...
In the phrase "Yes, it disables the AMC side for AM mode" - it should have read "Yes, it disables the AMC side ONLY in AM mode".
Also in that same paragraph...
I see that I needed to add "Until you are transmitting in either SSB mode -s"
You asked an important question that needed a better answer - one that I gave years ago was from an era that is no longer viable nor is it considered an acceptable method - for people want proof. This forum provides me that tool to give you the necessary proof on top of the reasons that you, or anyone else after you - needs to know for the LEGACY of the basic answer that was considered acceptable back when - is no longer considered to be an answer today.
When you have walked the miles I have, you'll understand that giving you the best answer is far more important than a simple answer that's been used for years, because I (or anyone else) says "that is the way it is" is not acceptable - we are needing - keeping - catching up with the research and times that we are in today. - what I did, or did not do, I need be more careful in my own review for although the post could withstand scrutiny, it did not answer your question with finality - I left out, unintentionally - key words that you could have used to help you understand the complexity of this radios' quirks with this simple question about limiters...
I come from a long line of love, but then there is the opposite effect too, I've been on websites that took to - attacked after, users on simple missed items that were not covered. The missing element was forgivable enough, but the quality of the answers that site required from it's user base - if not supplied - it's own users governed themselves by the adage that if you cannot give a full correct answer - then don't answer it at all. This level of thinking can damage the reputation that site has to offer - and perhaps you're blessed with someone whom has been attacked, that has seen that side and survived and still offers to help others. I may not have all the right answers - but I'm giving you my best answer to your question.
I am a work in progress.
Don't take this as a flame, because it's not - this is also trying to address an issue that has come up before...
The only thing I left out of this paragraph was "But not the Limiter for SSB, that being ALC"
I thought I had answered that in the next paragraph afterwards but I left out something you didn't know because I didn't put it in there - I presumed you knew...
In the phrase "Yes, it disables the AMC side for AM mode" - it should have read "Yes, it disables the AMC side ONLY in AM mode".
Also in that same paragraph...
I see that I needed to add "Until you are transmitting in either SSB mode -s"
You asked an important question that needed a better answer - one that I gave years ago was from an era that is no longer viable nor is it considered an acceptable method - for people want proof. This forum provides me that tool to give you the necessary proof on top of the reasons that you, or anyone else after you - needs to know for the LEGACY of the basic answer that was considered acceptable back when - is no longer considered to be an answer today.
When you have walked the miles I have, you'll understand that giving you the best answer is far more important than a simple answer that's been used for years, because I (or anyone else) says "that is the way it is" is not acceptable - we are needing - keeping - catching up with the research and times that we are in today. - what I did, or did not do, I need be more careful in my own review for although the post could withstand scrutiny, it did not answer your question with finality - I left out, unintentionally - key words that you could have used to help you understand the complexity of this radios' quirks with this simple question about limiters...
- for the question was two fold being that - in one section
But here's that "2nd fold" of the question -- "does it Disable The Modulation Limiter completely" - Answer No,
- and "basically the same as removing the transistor - Answer No.
- "Does it keep the Modulation Limiter working with just a boost in AM Modulation?"
That answer is the complex one. Most of the fingers point to yes, except the last one...
You're removing R131 - you disabled AMC side Modulation Control of the Envelope, . You get your "boost"
But...
ALC for SSB DOES WORK for AM side as well - as you can experience that when you turn VR11 down too far, in AM mode while you transmit, it can and will clamp.
This is what makes my job to answer such a statement, difficult - I have to, carefully, because of that post above shows that I missed something - you deserve a better answer - one scenario is; as if you wanted to run this radio into a small AMP to drive a larger amp to swing it using the smaller amp instead of the radio - you wouldn't have a straight answer until you tried to turn down SSB drive to make the amp swing the other amp - and then you switch over to AM mode and the ALC clamps on you - that does NOT fit the answer.That answer is the complex one. Most of the fingers point to yes, except the last one...
You're removing R131 - you disabled AMC side Modulation Control of the Envelope, . You get your "boost"
But...
ALC for SSB DOES WORK for AM side as well - as you can experience that when you turn VR11 down too far, in AM mode while you transmit, it can and will clamp.
All because an 18K resistor and the Diode and 8.2K resistor DO NOT sum up ENOUGH power to offset the trim level VR11 can control - including removing the power those two lines are sending it.
Lock - from the PLL - as well as AM mode switch.
IF the PLL wasn't LOCK'ed or was "Weak" that line goes low - and allows more signal to pass VR11's setting and trigger the ALC to activate quicker and prevent unapproved emissions from Type certification (Warble- unstable) (that 22K Resistor in the PLL / BCD switch line is part of this)
Lock - from the PLL - as well as AM mode switch.
IF the PLL wasn't LOCK'ed or was "Weak" that line goes low - and allows more signal to pass VR11's setting and trigger the ALC to activate quicker and prevent unapproved emissions from Type certification (Warble- unstable) (that 22K Resistor in the PLL / BCD switch line is part of this)
I come from a long line of love, but then there is the opposite effect too, I've been on websites that took to - attacked after, users on simple missed items that were not covered. The missing element was forgivable enough, but the quality of the answers that site required from it's user base - if not supplied - it's own users governed themselves by the adage that if you cannot give a full correct answer - then don't answer it at all. This level of thinking can damage the reputation that site has to offer - and perhaps you're blessed with someone whom has been attacked, that has seen that side and survived and still offers to help others. I may not have all the right answers - but I'm giving you my best answer to your question.
I am a work in progress.
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Hi LC!
Ahemn... - yes, you DO know, you worked these threads before...
https://www.worldwidedx.com/posts/725680/
https://www.worldwidedx.com/threads/over-130-modulation.163831/page-4#post-458159
Don't be playing 'possum...
The puppy one was cuter...
Ahemn... - yes, you DO know, you worked these threads before...
https://www.worldwidedx.com/posts/725680/
https://www.worldwidedx.com/threads/over-130-modulation.163831/page-4#post-458159
Don't be playing 'possum...
The puppy one was cuter...