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Jim HaRRIS

(no subject)

Hi,

Recently I was able to do a QSO on AM for the first time using my K3.
Yes, I have the 6 Khz filter installed. As I was setting power I found I
could dial in about 100 watts the same as SSB. Realizing that would
over work the PA I brought it back to 25 watts and had a very nice QSO
with a good audio report. Afterward, I checked the specs and
instructions in the Owner's Manual and could find nothing about AM power
rating.

What should be the power rating for the K3 when transmitting AM? Please
put that information in the manual. Would it be possible to limit the
AM power with a software update to eliminate the chance of
transmitting a signal that might be illegal and/or to prevent possible damage
to the KPA3?

Thanks and have a great day.

CU in the Colorado QSO Party Sept 4th, 2010.

73, Jim, W0EM

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W8JI

Re: (no subject)

Hi Jim

If you are interested in the details of AM you can read it here:

http://www.w8ji.com/amplitude_modulation.htm

Since the ratio of peak power to carrier is 4:1 in a symmetrically modulated
AM signal, the carrier power must be 25 watts or less with a 100-watt PEP
radio. I'm sure the K3 would be fine at 25 watts carrier, but without a
suitable scope and to be safe and allow for any asymmetry in modulation it
is a good idea to run less.

73 Tom

----- Original Message -----
From: "Jim Harris" <[hidden email]>
To: "Elecraft Email" <[hidden email]>
Sent: Saturday, June 19, 2010 12:37 PM
Subject: [Elecraft] (no subject)

>
> Hi,
>
>
>
> Recently I was able to do a QSO on AM for the first time using my K3.
> Yes, I have the 6 Khz filter installed. As I was setting power I found I
> could dial in about 100 watts the same as SSB. Realizing that would
> over work the PA I brought it back to 25 watts and had a very nice QSO
> with a good audio report. Afterward, I checked the specs and
> instructions in the Owner's Manual and could find nothing about AM power
> rating.
>
>
>
> What should be the power rating for the K3 when transmitting AM? Please
> put that information in the manual. Would it be possible to limit the
> AM power with a software update to eliminate the chance of
> transmitting a signal that might be illegal and/or to prevent possible
> damage
> to the KPA3?
>
>
>
> Thanks and have a great day.
>
> CU in the Colorado QSO Party Sept 4th, 2010.
>
> 73, Jim, W0EM
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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N5GE

Re: (no subject)

In reply to this post by Jim HaRRIS

On Sat, 19 Jun 2010 16:37:32 +0000, Jim Harris <[hidden email]> wrote:

Interesting, Jim. I did a search of the PDF Owner's Manual and came up with
zilch regarding AM transmit power suggestions or adjustments. That must be an
oversight.

Tom, N5GE
Licensed since 1976
QCWA Life Member 35102

[hidden email]
http://www.n5ge.com
http://www.swotrc.net

>Recently I was able to do a QSO on AM for the first time using my K3.
>Yes, I have the 6 Khz filter installed. As I was setting power I found I
> could dial in about 100 watts the same as SSB. Realizing that would
>over work the PA I brought it back to 25 watts and had a very nice QSO
>with a good audio report. Afterward, I checked the specs and
>instructions in the Owner's Manual and could find nothing about AM power
> rating.
[snip]

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Amateur Radio Operator N5GE

Grant Youngman

Re: (no subject)

The K3 automatically sets the correct carrier output level for AM -- approx. 1/4 the set carrier power. Fiddling is really not required.

The proper way to use the radio into an amp, for example, is put the radio in "tune", adjust the K3 output tand tune the amp to the desired PEP output level. (And heavily load the amp, the the way). When you key up in AM, the K3 drops the carrier to 1/4 the set power, which is the correct level.

The power rating on AM is by definition 100W PEP -- the same as SSB.

Grant/NQ5T

On Jun 19, 2010, at 4:37 PM, Radio Amateur N5GE wrote:

> On Sat, 19 Jun 2010 16:37:32 +0000, Jim Harris <[hidden email]> wrote:
>
> Interesting, Jim. I did a search of the PDF Owner's Manual and came up with
> zilch regarding AM transmit power suggestions or adjustments. That must be an
> oversight.
>
> Tom, N5GE
> Licensed since 1976
> QCWA Life Member 35102
>
> [hidden email]
> http://www.n5ge.com
> http://www.swotrc.net
>
>
>
>> Recently I was able to do a QSO on AM for the first time using my K3.
>> Yes, I have the 6 Khz filter installed. As I was setting power I found I
>> could dial in about 100 watts the same as SSB. Realizing that would
>> over work the PA I brought it back to 25 watts and had a very nice QSO
>> with a good audio report. Afterward, I checked the specs and
>> instructions in the Owner's Manual and could find nothing about AM power
>> rating.
> [snip]
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

N5GE

Re: (no subject)

On Sat, 19 Jun 2010 17:06:57 -0500, Grant Youngman <[hidden email]> wrote:

Thanks Grant! I wonder why they don't say something about that in the
manual?...

Tom, N5GE
Licensed since 1976
QCWA Life Member 35102

[hidden email]
http://www.n5ge.com
http://www.swotrc.net

>The K3 automatically sets the correct carrier output level for AM -- approx. 1/4 the set carrier power. Fiddling is really not required.
>
>The proper way to use the radio into an amp, for example, is put the radio in "tune", adjust the K3 output tand tune the amp to the desired PEP output level. (And heavily load the amp, the the way). When you key up in AM, the K3 drops the carrier to 1/4 the set power, which is the correct level.
>
>The power rating on AM is by definition 100W PEP -- the same as SSB.
>
>Grant/NQ5T
>
>
>On Jun 19, 2010, at 4:37 PM, Radio Amateur N5GE wrote:
>
>> On Sat, 19 Jun 2010 16:37:32 +0000, Jim Harris <[hidden email]> wrote:
>>
>> Interesting, Jim. I did a search of the PDF Owner's Manual and came up with
>> zilch regarding AM transmit power suggestions or adjustments. That must be an
>> oversight.

[snip]

______________________________________________________________
Elecraft mailing list
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Amateur Radio Operator N5GE

Mike Harris

Re: (no subject)

In reply to this post by N5GE

G'day,

It seems the fundamentals are no longer part of the examinations.

Regards,

Mike VP8NO

----- Original Message -----
From: "Radio Amateur N5GE" <[hidden email]>
To: "Elecraft Email" <[hidden email]>
Sent: Saturday, June 19, 2010 5:37 PM
Subject: Re: [Elecraft] (no subject)

> On Sat, 19 Jun 2010 16:37:32 +0000, Jim Harris <[hidden email]> wrote:
>
> Interesting, Jim. I did a search of the PDF Owner's Manual and
> came up with
> zilch regarding AM transmit power suggestions or adjustments.
> That must be an
> oversight.
>
> Tom, N5GE
> Licensed since 1976
> QCWA Life Member 35102
>
> [hidden email]
> http://www.n5ge.com
> http://www.swotrc.net
>
>
>
>>Recently I was able to do a QSO on AM for the first time using my
>>K3.
>>Yes, I have the 6 Khz filter installed. As I was setting power I
>>found I
>> could dial in about 100 watts the same as SSB. Realizing that
>> would
>>over work the PA I brought it back to 25 watts and had a very nice
>>QSO
>>with a good audio report. Afterward, I checked the specs and
>>instructions in the Owner's Manual and could find nothing about AM
>>power
>> rating.
> [snip]

Guy, K2AV

Re: (no subject)

In reply to this post by N5GE

Supposedly this would be license exam reference material, that AM
signals can vary instantaneously from nothing at full negative
modulation, to four times the carrier power at full positive
modulation. Therefore AM PEP is four times carrier power at full
modulation.

QRO limit today would be 1500/4 or 375 watts carrier output.

My 3-1000Z needs 55 watts input PEP for 1500 PEP out. 55/4 is 13.75
watts carrier to drive my Z box to today's legal limit AM signal.

The AM PEP value will always be the limiting factor in a string of
linear amplifiers, just as in SSB.

This stuff in the USA question pools?

If it isn't required for a license, maybe it ought to be in the manual.

In pre-1.5kw days the carrier INPUT power allowed was 1000 watts,
usually class C with plate modulation therefore putting out 750 watts
of carrier PLUS full modulation which meant those old Johnson desk
kilowatt rigs were putting out 750 watts carrier and 3KW PEP at high
modulation.

On Sat, Jun 19, 2010 at 6:15 PM, Radio Amateur N5GE <[hidden email]> wrote:

> On Sat, 19 Jun 2010 17:06:57 -0500, Grant Youngman <[hidden email]> wrote:
>
> Thanks Grant! I wonder why they don't say something about that in the
> manual?...
>
> Tom, N5GE
> Licensed since 1976
> QCWA Life Member 35102
>
> [hidden email]
> http://www.n5ge.com
> http://www.swotrc.net
>
>>The K3 automatically sets the correct carrier output level for AM -- approx. 1/4 the set carrier power. Fiddling is really not required.
>>
>>The proper way to use the radio into an amp, for example, is put the radio in "tune", adjust the K3 output tand tune the amp to the desired PEP output level. (And heavily load the amp, the the way). When you key up in AM, the K3 drops the carrier to 1/4 the set power, which is the correct level.
>>
>>The power rating on AM is by definition 100W PEP -- the same as SSB.
>>
>>Grant/NQ5T
>>
>>
>>On Jun 19, 2010, at 4:37 PM, Radio Amateur N5GE wrote:
>>
>>> On Sat, 19 Jun 2010 16:37:32 +0000, Jim Harris <[hidden email]> wrote:
>>>
>>> Interesting, Jim. I did a search of the PDF Owner's Manual and came up with
>>> zilch regarding AM transmit power suggestions or adjustments. That must be an
>>> oversight.
> [snip]
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

N5GE

Re: (no subject)

On Sat, 19 Jun 2010 21:57:28 -0400, Guy Olinger K2AV <[hidden email]>
wrote:

Gee Guy, I've never worked AM on any band and took my Novice test 1n 1976, the
General and Advanced on the same trip to Dallas from Oklahoma City in 1977. Took
the Extra in 1978.

Since I never use AM I don't feel I need to know anything except that the PEP
max is 1500W and that would certainly cover AM which if I were to use it would
show on the scope and the watt meters here.

The manual I spoke of was the Elecraft K3 Manual.

BT 73 ES GUD LUK
DE N5GE,
QCWA LIFE MEMBER 35102 AR SK

[hidden email]
http://www.n5ge.com

>Supposedly this would be license exam reference material, that AM
>signals can vary instantaneously from nothing at full negative
>modulation, to four times the carrier power at full positive
>modulation. Therefore AM PEP is four times carrier power at full
>modulation.
>
>QRO limit today would be 1500/4 or 375 watts carrier output.
>
>My 3-1000Z needs 55 watts input PEP for 1500 PEP out. 55/4 is 13.75
>watts carrier to drive my Z box to today's legal limit AM signal.
>
>The AM PEP value will always be the limiting factor in a string of
>linear amplifiers, just as in SSB.
>
>This stuff in the USA question pools?
>
>If it isn't required for a license, maybe it ought to be in the manual.
>
>In pre-1.5kw days the carrier INPUT power allowed was 1000 watts,
>usually class C with plate modulation therefore putting out 750 watts
>of carrier PLUS full modulation which meant those old Johnson desk
>kilowatt rigs were putting out 750 watts carrier and 3KW PEP at high
>modulation.
>
>On Sat, Jun 19, 2010 at 6:15 PM, Radio Amateur N5GE <[hidden email]> wrote:
>> On Sat, 19 Jun 2010 17:06:57 -0500, Grant Youngman <[hidden email]> wrote:
>>
>> Thanks Grant! I wonder why they don't say something about that in the
>> manual?...
>>
>> Tom, N5GE
>> Licensed since 1976
>> QCWA Life Member 35102
>>
>> [hidden email]
>> http://www.n5ge.com
>> http://www.swotrc.net
>>
>>>The K3 automatically sets the correct carrier output level for AM -- approx. 1/4 the set carrier power. Fiddling is really not required.
>>>
>>>The proper way to use the radio into an amp, for example, is put the radio in "tune", adjust the K3 output tand tune the amp to the desired PEP output level. (And heavily load the amp, the the way). When you key up in AM, the K3 drops the carrier to 1/4 the set power, which is the correct level.
>>>
>>>The power rating on AM is by definition 100W PEP -- the same as SSB.
>>>
>>>Grant/NQ5T
>>>
>>>
>>>On Jun 19, 2010, at 4:37 PM, Radio Amateur N5GE wrote:
>>>
>>>> On Sat, 19 Jun 2010 16:37:32 +0000, Jim Harris <[hidden email]> wrote:
>>>>
>>>> Interesting, Jim. I did a search of the PDF Owner's Manual and came up with
>>>> zilch regarding AM transmit power suggestions or adjustments. That must be an
>>>> oversight.
>> [snip]
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>

Amateur Radio Operator N5GE

Jim HaRRIS

Re: K3 AM Power Setting: Was (no subject)

In reply to this post by Grant Youngman

First let me apologize for sending out the first message without a subject. My mistake.

I appreciate all the responses to my questions. While Grants information below sounds reasonable and may well be correct I would like to see something in the manual about how the AM power setting functions. It does seem unusual that I set 25 watts with AM mode selected and received a 56 report from 1200 miles away. That would mean that slightly over six watts was actually transmitted.

Specifications of many other radio's speak of 25-40 watts for AM. The specifications and owners manual for the K3 does not address the details of AM power. And, I might add the same for FM. I would like to see Elecraft staff address this so there is no misunderstanding.

CU in the Colorado QSO Party on September 4th, 2010.

Jim, W0EM

Andy Wood

Re: K3 AM Power Setting: Was (no subject)

Hi Jim,

I have used my K3 on AM quite a bit recently and can share a few ideas and experiences with you.

First of all, the information you have received so far about the indicated power level on the K3 is correct - the K3 power display shows PEP reading. So, 100w on the display is equivalent to 25w of carrier in AM TX.

Do not use the compressor at all on AM TX - set it to zero. I looked at the TX output of my K3 with a 'scope, and, with the compressor on, there appears to be an extra "bubble" in the waveform at the zero crossing point. I know, not the most technical description. Maybe someone can enlighten us on what this is called and what the cause is? This is noticeable as increased distortion when monitoring the TX on a second receiver too.

It seems impossible to drive the K3 in excess of 100% modulation without the compressor, even with the mic gain at maximum. I think there are some pretty good "smarts" in there to keep the waveform clean. As a rule, I always set the audio drive by the ALC meter, trying to keep the peaks around the fifth ALC "bar", with only very brief excursions to bar 6 and 7. This works for me and I receive good signal reports.

Hope this info is of some help.

Andy VK4KY

Grant Youngman

Re: K3 AM Power Setting: Was (no subject)

In reply to this post by Jim HaRRIS

It wouldn't hurt to have something in the manual, but what I described is the correct way to adjust the K3 for AM operation.

In AM mode, use TUNE to adjust your external amp, NOT Transmit. TUNE will let you get to a full 100W carrier out of the K3, or whatever level your amp needs to get to the desired PEP level. XMT (or PTT, whatever) will change K3 power out to the correct carrier level, which is 1/4 the indicated PEP. Load the amp to the desired PEP (not carrier) level.

You can adjust the PWR setting in AM mode when transmitting, but the K3 indicated power will be PEP -- not actual carrier power -- which again, will be 1/4 of the indicated power level. This is set for you automatically in the K3, so you don't have to worry about it. Trying to use 40 watts carrier out for example on a typical modern 100W PEP radio will either reduce your modulation percentage or distort and sound pretty rotten, or both.

Barefoot, you'll have (within someone's ability to distinguish) about the same power out as a Ranger. If you're going to drive an amp to increase power, then make sure the amp can safely go key down for many minutes at the (carrier) power level you want to run -- which would be 375W (roughly) for a (roughly) legal limit AM signal. I can push my AL-1200 that way all day, but usually don't run it at more than around 250W carrier (tuned up to 1KW to get the PEP level correct).

Grant/NQ5T

On Jun 20, 2010, at 9:21 PM, Jim HaRRIS wrote:

>
> First let me apologize for sending out the first message without a subject.
> My mistake.
>
> I appreciate all the responses to my questions. While Grants information
> below sounds reasonable and may well be correct I would like to see
> something in the manual about how the AM power setting functions. It does
> seem unusual that I set 25 watts with AM mode selected and received a 56
> report from 1200 miles away. That would mean that slightly over six watts
> was actually transmitted.
>
> Specifications of many other radio's speak of 25-40 watts for AM. The
> specifications and owners manual for the K3 does not address the details of
> AM power. And, I might add the same for FM. I would like to see Elecraft
> staff address this so there is no misunderstanding.
>
> CU in the Colorado QSO Party on September 4th, 2010.
>
> Jim, W0EM
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/no-subject-tp5199002p5202723.html
> Sent from the [K3] mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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