RM Italy KL-503... So far so good!

[jwr1221]

Hey all,

I haven't been able to find much on-line about the "new" KL-503 from RM Italy so I thought I'd share my first impressions... Just finally got a chance to put it in my truck last night and played with it a bit today... I'm using a Galaxy 949 from Sparky's and a Wilson 2000 antenna.

I checked my "sparked" 949 and with the RF output at the minimum it's putting out 1W deadkey on AM and around 10W PEP on SSB... (Measured with a Radio Shack power meter, so take those readings for what they're worth ) If the AM deadkey is bumped up to 2W, then it is doing around 15W PEP on SSB. Since this amp is rated at 6W max DK and 12W max PEP, I decided to just run it at the minimum on both AM and SSB...

Using the same RS power meter, here's what I'm getting for output: (approximate readings of course! - The scale on the meter makes you guess a bit...)

Power Level 1: 10W DK on AM and 100W PEP on SSB
Power Level 2: 20W DK on AM and 200W PEP on SSB
Power Level 3: 25W DK on AM and 225W PEP on SSB
Power Level 4: 50W DK on AM and 250W PEP on SSB
Power Level 5: 60W DK on AM and 300W PEP on SSB
Power Level 6: 120W DK on AM and 350W PEP on SSB

The specs for the amp show up to 650W PEP, but I'm not so sure about that...

I don't have a frequency generator so to get the readings on SSB, I just gave it a whistle... On AM, I got numerous "loud and clear" reports, but couldn't find any SSB action to try to jump into to get some feedback...

It is small enough to have it mounted right on top of my radio, which itself is on a hump mount in my truck with an external speaker... I didn't use it that much yet, so I can't comment on heat levels

So far it seems like a pretty nice amp for less than $130... I'm really curious to see how clean it is on SSB though... I'm in NW PA (Erie)... Anyone else on this board around me to give me a radio check????

-JWR1221

[Nagant]

I'm glad to read a report on one of these. Thanks for sharing and keep us posted on SSB results. I run its little mosfet brother the KL203 of and on. It has worked well for me for around 8 months or so including on SSB.

[tonyvlx]

Im running a KL300P and i get great reports on SSB. Im actually on my 2nd amp. The first one blew a relay only after a few months of moderate use. It was replaced under warranty.So far so good.

[PA629]

Hey all,

I haven't been able to find much on-line about the "new" KL-503 from RM Italy so I thought I'd share my first impressions... Just finally got a chance to put it in my truck last night and played with it a bit today... I'm using a Galaxy 949 from Sparky's and a Wilson 2000 antenna.

I checked my "sparked" 949 and with the RF output at the minimum it's putting out 1W deadkey on AM and around 10W PEP on SSB... (Measured with a Radio Shack power meter, so take those readings for what they're worth ) If the AM deadkey is bumped up to 2W, then it is doing around 15W PEP on SSB. Since this amp is rated at 6W max DK and 12W max PEP, I decided to just run it at the minimum on both AM and SSB...

Using the same RS power meter, here's what I'm getting for output: (approximate readings of course! - The scale on the meter makes you guess a bit...)

Power Level 1: 10W DK on AM and 100W PEP on SSB
Power Level 2: 20W DK on AM and 200W PEP on SSB
Power Level 3: 25W DK on AM and 225W PEP on SSB
Power Level 4: 50W DK on AM and 250W PEP on SSB
Power Level 5: 60W DK on AM and 300W PEP on SSB
Power Level 6: 120W DK on AM and 350W PEP on SSB

The specs for the amp show up to 650W PEP, but I'm not so sure about that...

I don't have a frequency generator so to get the readings on SSB, I just gave it a whistle... On AM, I got numerous "loud and clear" reports, but couldn't find any SSB action to try to jump into to get some feedback...

It is small enough to have it mounted right on top of my radio, which itself is on a hump mount in my truck with an external speaker... I didn't use it that much yet, so I can't comment on heat levels

So far it seems like a pretty nice amp for less than $130... I'm really curious to see how clean it is on SSB though... I'm in NW PA (Erie)... Anyone else on this board around me to give me a radio check????

-JWR1221

Around this part of the state? Probably just me, but then you already knew that. Try to catch me or one of the local bases on ch.10 and ask for a SSB check. Later.....

[Wing Ding]

what transistors and how many are in this new kl-503? i, too, couldn't find much about the schematics of the amp. looks to be one helluva deal for less than $150, shipped. thanx in advance.

[silvereagle1]

I know this is an old thread but that's good in a way. I just ordered the kl503 and should get it by Wednesday. Since this topic is kind of old now maybe we can find out some updated info on sideband reports. Maybe from some kl503 users. Mark

[743]

Hello. My first linear was a KL 503. It was a perfect match for my Bearcat 980SSB. Just wondering what meter you were reading your output with. My output measured to specification using a DOSY Test Center. I always ran mine in position 3.

743

---

Wednesday, 25 December 2013, 14:45 PM

Hello. My first linear was a KL 503. It was a perfect match for my Bearcat 980SSB. Just wondering what meter you were reading your output with. My output measured to specification using a DOSY Test Center. I always ran mine in position 3.

743

[silvereagle1]

Hello. My first linear was a KL 503. It was a perfect match for my Bearcat 980SSB. Just wondering what meter you were reading your output with. My output measured to specification using a DOSY Test Center. I always ran mine in position 3.

743

---

Wednesday, 25 December 2013, 14:45 PM

Hello. My first linear was a KL 503. It was a perfect match for my Bearcat 980SSB. Just wondering what meter you were reading your output with. My output measured to specification using a DOSY Test Center. I always ran mine in position 3.

743

Greetings 743, I'm glad someone revived this topic. Just wondering what your max output was on setting 6 dead key only with a 1 watt input from the radio or whatever your radio dead key was set too. Just curious. I've had ten different theory's thrown at me to what the proper safe setting should be. You being an actual user of the 503 you could ease my mind a lot. Thanks mark.

[743]

The input power was 5 watts. I documented 100W in switch position 1 and 300 watts in position 6. Afterwards I left it in position 3 as this provided the best input impedance and didn't overdrive the linear. The difference in output power between position 3 and position 6 would not have made a difference on the listener's S meter. To gain 1 "S" unit requires 4 times the power. If someone runs 100watts on AM and is an S4 on the listeners radio it would require 400 watts to get a reading of S5.

If still confused let me know.

743

[silvereagle1]

The reason I ask was I was putting a 2 watt dead key into my 503 and dead keying over 100 watts out on setting six. I always thought this was ok. But a fellow member told me that it doesn't matter how low my dead key is that the amp should not put out more than 50 watts on any setting or the transistors will blow. I don't know how true it is but I've been running mine on 1 watt ever since. With a 1 watt dead key out of my radio I have around 75-80 coming out of the amp on setting six now.
I've always thought it was the dead key wattage going into the amp that would actually do damage to the transistors not the wattage coming out of the amp. It makes sense to me that setting six would put out about 100 watts or more. That's what I always believed.. What are your thoughts being a 503 user? If you get a chance read "dead key question" topic I believe by Cochise a few months back from top to bottom and give me your thoughts.

[743]

Ok, I think I understand what's going on. I don't think you are reading the amount of swing in output power from your radio. You are using your dead key measurement and adjusting the KL 503 for max output. Here is what needs to be done. Using only the AM mode and with your radio only, hook it to the watt meter connected to the antenna you are using. With modulation turned down to zero key the radio and note the output power. This will be your Dead Key measurement. Next, turn up the modulation for 100% modulation. Speak into the microphone or do a long Ahhhhhh or AAAuuudddiiiooo and note how high the output power goes to on your watt meter. This will be your "swing" and will determine the power level setting for your KL 503 on AM. Simply connect the amp with the switch in position 3. Do the aaauuudddiiiooo thing again and note the output from your amp. You want to see about 250 - 260 watts on AM and no more. Adjust the KL 503 switch setting to be as close to this as possible. If you go to position 6 and are getting 300W or more you are overdriving the amp which is a no no. Some people have bragged to me that "wow, I can switch it to the max and get another 50 - 60 watts!" Well, not for long. To the listener's radio "S" meter the extra 50 or 60 watts wouldn't even budge the "S" meter. This is the simple version I've mentioned without getting into hooking up a 1 KHZ tone generator and adjusting for 100% modulation using a 50 ohm dummy load and all that.

After you have found the 250W position leave it there. Switch to side band and talk. Note what the power swings up to. Do not readjust the switch setting as for SSB you get what you get. If you get a chance let me know how it works out and what your readings are.

Cheers and Happy New Year....well at least in a few days anyway. 743

[silvereagle1]

Ok, I think I understand what's going on. I don't think you are reading the amount of swing in output power from your radio. You are using your dead key measurement and adjusting the KL 503 for max output. Here is what needs to be done. Using only the AM mode and with your radio only, hook it to the watt meter connected to the antenna you are using. With modulation turned down to zero key the radio and note the output power. This will be your Dead Key measurement. Next, turn up the modulation for 100% modulation. Speak into the microphone or do a long Ahhhhhh or AAAuuudddiiiooo and note how high the output power goes to on your watt meter. This will be your "swing" and will determine the power level setting for your KL 503 on AM. Simply connect the amp with the switch in position 3. Do the aaauuudddiiiooo thing again and note the output from your amp. You want to see about 250 - 260 watts on AM and no more. Adjust the KL 503 switch setting to be as close to this as possible. If you go to position 6 and are getting 300W or more you are overdriving the amp which is a no no. Some people have bragged to me that "wow, I can switch it to the max and get another 50 - 60 watts!" Well, not for long. To the listener's radio "S" meter the extra 50 or 60 watts wouldn't even budge the "S" meter. This is the simple version I've mentioned without getting into hooking up a 1 KHZ tone generator and adjusting for 100% modulation using a 50 ohm dummy load and all that.

After you have found the 250W position leave it there. Switch to side band and talk. Note what the power swings up to. Do not readjust the switch setting as for SSB you get what you get. If you get a chance let me know how it works out and what your readings are.

Cheers and Happy New Year....well at least in a few days anyway. 743

It only swings to about 240 on am. I guess I should have said it this way:
With a 2 watt dead key Input from my radio I had well over a hundred watt dead key coming out of the amp then swinging around 240. This was on setting six. I have been told anything over a 50 watt dead key coming out of the AMP would blow the transistors. I now drive my kl503 with just under 1 watt dead key. On setting six I now have around 60 watt dead key coming out of the amp instead of over a hundred. It swings up from the sixty. I think I said about 85 in previous post I was wrong its about 60 give or take.

---

Friday, 27 December 2013, 21:30 PM

Hey all,

I haven't been able to find much on-line about the "new" KL-503 from RM Italy so I thought I'd share my first impressions... Just finally got a chance to put it in my truck last night and played with it a bit today... I'm using a Galaxy 949 from Sparky's and a Wilson 2000 antenna.

I checked my "sparked" 949 and with the RF output at the minimum it's putting out 1W deadkey on AM and around 10W PEP on SSB... (Measured with a Radio Shack power meter, so take those readings for what they're worth ) If the AM deadkey is bumped up to 2W, then it is doing around 15W PEP on SSB. Since this amp is rated at 6W max DK and 12W max PEP, I decided to just run it at the minimum on both AM and SSB...

Using the same RS power meter, here's what I'm getting for output: (approximate readings of course! - The scale on the meter makes you guess a bit...)

Power Level 1: 10W DK on AM and 100W PEP on SSB
Power Level 2: 20W DK on AM and 200W PEP on SSB
Power Level 3: 25W DK on AM and 225W PEP on SSB
Power Level 4: 50W DK on AM and 250W PEP on SSB
Power Level 5: 60W DK on AM and 300W PEP on SSB
Power Level 6: 120W DK on AM and 350W PEP on SSB

The specs for the amp show up to 650W PEP, but I'm not so sure about that...

I don't have a frequency generator so to get the readings on SSB, I just gave it a whistle... On AM, I got numerous "loud and clear" reports, but couldn't find any SSB action to try to jump into to get some feedback...

It is small enough to have it mounted right on top of my radio, which itself is on a hump mount in my truck with an external speaker... I didn't use it that much yet, so I can't comment on heat levels

So far it seems like a pretty nice amp for less than $130... I'm really curious to see how clean it is on SSB though... I'm in NW PA (Erie)... Anyone else on this board around me to give me a radio check????

-JWR1221

My readings were very similar to his
If you notice on power level six he is putting out 120 dk. I was told that this would burn up the transistors. Even on the high setting of power level six it should not DK more than 50 or 60 out of the amp. More than one person has told me this but im stubborn lol. I want to get more than one or two opinions. With that said you as 503 user I just wanted your thoughts.
And by the way i talk to 590 in Phoenix all the time maybe we could all get together sometime. Mark

[Whiskey Man]

This is interesting and somewhat confusing to me. I have a kl203p which is rated at 10w in get 100w out on am and 20w in get 200w out on ssb. I use it with a radio that dk 1.5w and swings 12 on my everyday meter. On my bird it's more like 8 or 9 swing so let's say avg. of 10w. Hooked to this 203 it dk around 40 to 45 on am and swings to 180. Now I know the swing on this radio is 12 or less but I'm getting ssb power on am. I feel like I'm giving it what the specs call for but I'm seeing more than should. I figure what the heck, it's got a fuse inside it and I've got one inline so let's hope they blow first. LOL

---

Tuesday, 29 April 2014, 8:37 AM

This is interesting and somewhat confusing to me. I have a kl203p which is rated at 10w in get 100w out on am and 20w in get 200w out on ssb. I use it with a radio that dk 1.5w and swings 12 on my everyday meter. On my bird it's more like 8 or 9 swing so let's say avg. of 10w. Hooked to this 203 it dk around 40 to 45 on am and swings to 180. Now I know the swing on this radio is 12 or less but I'm getting ssb power on am. I feel like I'm giving it what the specs call for but I'm seeing more than should. I figure what the heck, it's got a fuse inside it and I've got one inline so let's hope they blows first. LOL

I wish I knew how to edit, I would take the s off that blow. My bad!!!

(edited by MDY)

[silvereagle1]

I used to get confused at first because everyone's an expert. 10 people with 10 different answers and they are all right and won't back down from what they say and believe. One guy wrote a book explaining to me how I was going to blow up my amp with a 2 watt DK. I thought he was a 30 year veteran ham but turns out he's been in the hobby for a couple of years and gets all his info from reading. well, it's been almost a year now and my amp is still going strong and rarely gets warm. no muffled up sound or distortion. And most of this time I was driving it with a 99v2 dual final radio at 1.5 to 2 watts. I don't get confused anymore! I just run with what i have. GI joes done the mod on my 99v2 and he said that radio is amp ready no problem. he was right but then he's a legit tech not just someone with an opinion. I have yet to find anyone that has blown up a kl503 with a 2 watt key swinging less the 20 watts. Could be wrong. But I stopped worrying about rather I was going to blow my amp or not. I'm having fun with what I have. It suits me and that's all that matters. Good luck with your amp and enjoy.

[MDYoungblood]

This is interesting and somewhat confusing to me. I have a kl203p which is rated at 10w in get 100w out on am and 20w in get 200w out on ssb. I use it with a radio that dk 1.5w and swings 12 on my everyday meter. On my bird it's more like 8 or 9 swing so let's say avg. of 10w. Hooked to this 203 it dk around 40 to 45 on am and swings to 180. Now I know the swing on this radio is 12 or less but I'm getting ssb power on am. I feel like I'm giving it what the specs call for but I'm seeing more than should. I figure what the heck, it's got a fuse inside it and I've got one inline so let's hope they blow first. LOL

---

Tuesday, 29 April 2014, 8:37 AM

This is interesting and somewhat confusing to me. I have a kl203p which is rated at 10w in get 100w out on am and 20w in get 200w out on ssb. I use it with a radio that dk 1.5w and swings 12 on my everyday meter. On my bird it's more like 8 or 9 swing so let's say avg. of 10w. Hooked to this 203 it dk around 40 to 45 on am and swings to 180. Now I know the swing on this radio is 12 or less but I'm getting ssb power on am. I feel like I'm giving it what the specs call for but I'm seeing more than should. I figure what the heck, it's got a fuse inside it and I've got one inline so let's hope they blows first. LOL

I wish I knew how to edit, I would take the s off that blow. My bad!!!



(edited by MDY)

I took care of that for you Whiskey Man, edit comes into play after you get to 100+ posts, you are on the downhill side of that so you don't have long to wait.

3's

Greg

[Whiskey Man]

This is interesting and somewhat confusing to me. I have a kl203p which is rated at 10w in get 100w out on am and 20w in get 200w out on ssb. I use it with a radio that dk 1.5w and swings 12 on my everyday meter. On my bird it's more like 8 or 9 swing so let's say avg. of 10w. Hooked to this 203 it dk around 40 to 45 on am and swings to 180. Now I know the swing on this radio is 12 or less but I'm getting ssb power on am. I feel like I'm giving it what the specs call for but I'm seeing more than should. I figure what the heck, it's got a fuse inside it and I've got one inline so let's hope they blow first. LOL

---

Tuesday, 29 April 2014, 8:37 AM

This is interesting and somewhat confusing to me. I have a kl203p which is rated at 10w in get 100w out on am and 20w in get 200w out on ssb. I use it with a radio that dk 1.5w and swings 12 on my everyday meter. On my bird it's more like 8 or 9 swing so let's say avg. of 10w. Hooked to this 203 it dk around 40 to 45 on am and swings to 180. Now I know the swing on this radio is 12 or less but I'm getting ssb power on am. I feel like I'm giving it what the specs call for but I'm seeing more than should. I figure what the heck, it's got a fuse inside it and I've got one inline so let's hope they blows first. LOL

I wish I knew how to edit, I would take the s off that blow. My bad!!!



(edited by MDY)

I took care of that for you Whiskey Man, edit comes into play after you get to 100+ posts, you are on the downhill side of that so you don't have long to wait.

3's

Greg

So then this makes me one closer. Thanks Greg!!!

[743]

Whoa folks,

I just saw this and had to jump in. Maybe this is old, maybe not. I have owned 3 KL500s over the past. For some reason I buy one then sell it on E you know who for a loss. Last one I had was blue in color and didn't require moving a jumper. Yeah I sold that one too. But all of them met their published specs in switch position 3. I found position 3 to be the sweet spot impedance wise. They do meet and exceed their published specs. The problem is when you go past position 3. Yeah go to position 6 for 50 more watts on AM. The increase wouldn't even be noticed on someone's "S" meter. But your driver radio will feel it, no doubt about it. So will the KL 500. RM of Italy makes some pretty good amps. I read one comment that said "they are no good, have you seen their output on a spectrum analyzer? It looks like hair! Well, most linears in this cost range do. And even some very expensive amplifiers look like hair. That's what low pass filters are for in CB land. Anyway back to RMs KL 500, KL 200, KL whatever. Solid state linears require some special care. Thou shalt not over drive ye solid state linear lest ye over heat them and degrade the input driver section where tiny cracks begin to form that are so small they can only be seen by an electron microscope. The aluminum or whatever conductor type used begins to physically move and form hills and valleys (an effect due to the amount of current flowing Vs. the conductor size and it's metallic ability to cope with the current flow IE: The current density factor. A driver transistor or a power transistor often contains thousands of smaller transistors all interconnected by a conductor one millionth the size of a human hair. The end effect can result in a density factor of more than 1000 ampere inches. Enough to cause the interconnecting metal traces to actually move or migrate to the point where the conductor size can no longer be sustained and one transistor fails out of 1000. Now the rest must share the load and as more and more fail the shared load must dissipate an increasing amount of heat. Eventually it reaches a sudden thermal runaway which can't be stopped and the device completely fails. A cascade effect wherein the transistor completely fails, usually resulting in a momentary short circuit that is blown open by the current being handled. Now we have an open circuit and nothing works anymore, our amplifier is dead. Why? Just because someone wanted more amplification than that stated by the specification. Having been a Electronic Component Failure Analysis Engineer for Military devices I've seen just about everything from the early dreaded Purple Plague to the later ESD failures and now the simple and preventable EOS or Electrical Over Stress failure which is the most common failure "mode" seen today by us CBrs and some Hams too. I'll shut up now. Sometimes I can get carried away by what to me is the obvious.

743 in Phoenix

[Whiskey Man]

Whoa folks,

I just saw this and had to jump in. Maybe this is old, maybe not. I have owned 3 KL500s over the past. For some reason I buy one then sell it on E you know who for a loss. Last one I had was blue in color and didn't require moving a jumper. Yeah I sold that one too. But all of them met their published specs in switch position 3. I found position 3 to be the sweet spot impedance wise. They do meet and exceed their published specs. The problem is when you go past position 3. Yeah go to position 6 for 50 more watts on AM. The increase wouldn't even be noticed on someone's "S" meter. But your driver radio will feel it, no doubt about it. So will the KL 500. RM of Italy makes some pretty good amps. I read one comment that said "they are no good, have you seen their output on a spectrum analyzer? It looks like hair! Well, most linears in this cost range do. And even some very expensive amplifiers look like hair. That's what low pass filters are for in CB land. Anyway back to RMs KL 500, KL 200, KL whatever. Solid state linears require some special care. Thou shalt not over drive ye solid state linear lest ye over heat them and degrade the input driver section where tiny cracks begin to form that are so small they can only be seen by an electron microscope. The aluminum or whatever conductor type used begins to physically move and form hills and valleys (an effect due to the amount of current flowing Vs. the conductor size and it's metallic ability to cope with the current flow IE: The current density factor. A driver transistor or a power transistor often contains thousands of smaller transistors all interconnected by a conductor one millionth the size of a human hair. The end effect can result in a density factor of more than 1000 ampere inches. Enough to cause the interconnecting metal traces to actually move or migrate to the point where the conductor size can no longer be sustained and one transistor fails out of 1000. Now the rest must share the load and as more and more fail the shared load must dissipate an increasing amount of heat. Eventually it reaches a sudden thermal runaway which can't be stopped and the device completely fails. A cascade effect wherein the transistor completely fails, usually resulting in a momentary short circuit that is blown open by the current being handled. Now we have an open circuit and nothing works anymore, our amplifier is dead. Why? Just because someone wanted more amplification than that stated by the specification. Having been a Electronic Component Failure Analysis Engineer for Military devices I've seen just about everything from the early dreaded Purple Plague to the later ESD failures and now the simple and preventable EOS or Electrical Over Stress failure which is the most common failure "mode" seen today by us CBrs and some Hams too. I'll shut up now. Sometimes I can get carried away by what to me is the obvious.

743 in Phoenix

You lost me at hello

[743]

Hello Ya'll,

I received an email to the effect if I didn't post I was going to be in DEEP DO DO or something like that. Sometimes I get carried away with yakking a lot over what ever. I can see from my previous post and the reply there to, caused some confusion. I think this was about how over driving an amplifier and the results of being mismatched impedance wise causing the crest of the MTBF graph (Mean Time Between Failures) to move to move in the wrong direction. IE: life cycle is shortened by those two factors which are an amplifier that is over driven or the impedance mismatch that happen between the exciter and the amplifier. Sometimes we don't pay attention to these areas and we find that something doesn't work any more. Amplifiers are an interesting subject for me and a hobby at the same time. Simple as that. 73s, 88s (where they apply) and may God Bless.

743

[Whiskey Man]

Hello Ya'll,

I received an email to the effect if I didn't post I was going to be in DEEP DO DO or something like that. Sometimes I get carried away with yakking a lot over what ever. I can see from my previous post and the reply there to, caused some confusion. I think this was about how over driving an amplifier and the results of being mismatched impedance wise causing the crest of the MTBF graph (Mean Time Between Failures) to move to move in the wrong direction. IE: life cycle is shortened by those two factors which are an amplifier that is over driven or the impedance mismatch that happen between the exciter and the amplifier. Sometimes we don't pay attention to these areas and we find that something doesn't work any more. Amplifiers are an interesting subject for me and a hobby at the same time. Simple as that. 73s, 88s (where they apply) and may God Bless.

743

Actually you make good sense but no one has answered my question as to why I'm seeing ssb numbers out of this amp on am with only 12 watts drive. They are supposed to be only 100 w with 10 w drive on am and with 12 w I'm seeing 180 w. They are known to be fragile and I run a fan on mine and constantly check the heat but just wondering you know.

[743]

Hello Ya'll,

I'm not sure if we're talking about a KL 503 or KL 200. Correct me if I'm wrong (which happens a lot) but I think the subject is that one is not seeing the output power on SSB that the user thinks he should be seeing. The answer is both easy, and complicated. I'll go for the easy part first to know if I'm on the right track here. There is only one way to measure output power on both AM and SSB. Forget for the moment what you see on your meter. Peak envelope power (PEP) is the highest envelope power supplied to the antenna transmission line by our CB transmitters during any full undistorted RF cycle or series of complete radio frequency cycles.

AM PEP; on your SSB radio, with a truly perfectly symmetrical signal and with exactly 100% modulation of the carrier, PEP output of your AM/SSB radio is roughly four times its carrier PEP; IE: a typical modern 100-watt CB export transceiver is usually rated for no more than, and often less than, 25 watts carrier output when operating in the AM mode. PEP vs. Average Power: PEP is roughly equal to steady carrier power, or CW dot and dash average power, in a properly-formed CW transmission which we don't or at least I don't use but bet I could still read at least 10 - 15 WPM. This is just for an example only and may or may not help. PEP bears no particular ratio or mathematical relationship to longer-term average power in distorted envelopes, such as a transmitted waveform with power overshoot, or with complex amplitude modulated waveforms, such as SSB or AM voice transmissions. Typical average power of a SSB voice transmission, for example, is 10-20% of PEP. The percentage of longer term average power to PEP increases with processing, and commonly reaches ~50% with extreme speech processing.

PEP Level Control for some of the more expensive export radios use PEP to adjust output power when using a linear which of course none of us use. Using an ALC (automatic level control) system. Time delay in the ALC system and finite time of RF signals passing through multiple stages, narrow filters for example often provides unusual envelope distortion. This distortion commonly appears as envelope power overshoot on leading edges, and sometimes causes negative carrier shift on AM. Some poorer designed transceivers have a short term envelope power overshoot several times the steady-state PEP setting. This envelope overshoot further complicates definitions of PEP and average power.

Well if you haven't figured it all out yet you can see that just about everything affects PEP. The only way I know of to measure actual PEP is by the use of a scope with a calibrated sampler accessory and look at the wave form. For AM Dead Key the signal is easy to read. So why do we get weird readings on our watt meters when we use SSB? Many of the expensive peak reading meters are pretty good at getting the display to read the actual true peak signal. On SSB can't do this as there's no carrier. What I do is transmit in SSB and multiply by two what I see on my MFJ-828 or DOSY to get a peak to peak number. The number is not Peak Envelope Power by any means but it does bring my SSB output power to be more in line with what I think it should be.
I'm working with a fellow who is marketing a circuit he claims will provide an accurate PEP number. I'm a bit skeptical at this time. But if it works or gets close you all will know just after I do.

Well, I hope I have helped at least a little bit anyway. Let me know and I can get more detailed. But as you have seen, my "more detailed" can run-amuck.

73s, 88s (where they apply) and may God Bless.

743 in Phoenix

[Foliant]

Some time ago i grabbed a defective KL-503 (the new Silver with bigger heatsink) on ebay.
After some research, a package arriving from Italy (some original Mosfets) and soldering its doing a great job now.

Have never expected to reach 280W in FM but got it. Saw 320 PEP on SSB.
Max. 250 sems right for good sound and a long life...

So all is like i expected and extrapolated from 140-160W out of my KL-203.

Maybe i use it in the mobile...