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ALC and the K3

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NK7Z

ALC and the K3

I want to run ALC for my amp if for no other reason to protect the amp
from overpower events. I understand Elecraft does not recommend the use
of ALC...

Exactly why is that?

--
73s and thanks,
Dave
NK7Z
http://www.nk7z.net
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Josh Fiden

Re: ALC and the K3

It creates garbage in your transmitted signal when ALC wiggles. If you keep drive power set low enough that ALC doesn't activate, it's okay.

Better option is to use the K3's xmit inhibit line if your amp supports it.

73
Josh W6XU

Sent from my mobile device

> On Dec 21, 2017, at 9:45 AM, Dave Cole (NK7Z) <[hidden email]> wrote:
>
> I want to run ALC for my amp if for no other reason to protect the amp from overpower events. I understand Elecraft does not recommend the use of ALC...
>
> Exactly why is that?
>

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NK7Z

Re: ALC and the K3

Thank you for the information, however I just want to reduce the
possibility of excessive voice peaks via ALC, not to do compression via
ALC.

We all make errors, and I would like to reduce the possibility of
hitting the amp too hard on voice peaks in the event I miss adjust the
K3 output level.

73s and thanks,
Dave
NK7Z
http://www.nk7z.net

On 12/21/2017 09:56 AM, Josh wrote:

> It creates garbage in your transmitted signal when ALC wiggles. If you keep drive power set low enough that ALC doesn't activate, it's okay.
>
> Better option is to use the K3's xmit inhibit line if your amp supports it.
>
> 73
> Josh W6XU
>
> Sent from my mobile device
>
>> On Dec 21, 2017, at 9:45 AM, Dave Cole (NK7Z) <[hidden email]> wrote:
>>
>> I want to run ALC for my amp if for no other reason to protect the amp from overpower events. I understand Elecraft does not recommend the use of ALC...
>>
>> Exactly why is that?
>>
>

Don Wilhelm

Re: ALC and the K3

In reply to this post by NK7Z

Dave,

The K3 does not overshoot due to the way output power is controlled (it
is different than other amateur transceivers in that regard.
So unless the amplifier contains protective circuits which activate the
ALC for excessive SWR or other amplifier faults, there is no need to
connect the ALC line. Even if the amp contains such protective
circuits, adjust the ALC in the amp so it does not activate with normal
operation.
Set the power so the amplifier is not overdriven.

If the ALC is activated in normal operation you will be creating
excessive IMD in your transmit signal - you can hear a lot of that going
on during a contest weekend.

The K3 has a menu setting (PWR SET) that can allow you to set the
maximum power on a per-band basis. You can use that to avoid
overdriving the amplifier.

73,
Don W3FPR

On 12/21/2017 12:45 PM, Dave Cole (NK7Z) wrote:
> I want to run ALC for my amp if for no other reason to protect the amp
> from overpower events. I understand Elecraft does not recommend the use
> of ALC...
>
> Exactly why is that?
>
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Bob McGraw - K4TAX

Re: ALC and the K3

In reply to this post by NK7Z

As a rule ALC is not needed and is not recommended by Elecraft. The K3
power management system with the internal ALC is far superior to the
derived voltage from most all amps. And, unlike many radios which when
operated with reduced power, they do have a propensity to overshoot, the
K3 series has firm ALC control at all power levels.

Just tune and load the amp for maximum output and then reduce drive
power from the K3 to attain the level of power you desire to operate.
And as a note, after tuning and loading to maximum output, do not
re-tweak the controls for or at the lower power operation. This is a
common misunderstanding among hams. If it is linear at 1500 watts, then
reducing drive, it will be linear at 500 watts. If one re-tweaks at
lower power it most likely won't be linear at 1500 watts or any lesser
peak there of. It will more likely be a "splatter generator".

73

Bob, K4TAX

On 12/21/2017 11:45 AM, Dave Cole (NK7Z) wrote:
> I want to run ALC for my amp if for no other reason to protect the amp
> from overpower events. I understand Elecraft does not recommend the
> use of ALC...
>
> Exactly why is that?
>

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Josh Fiden

Re: ALC and the K3

In reply to this post by NK7Z

The problem I've had in the past using ALC in that manner is that it was transparent to me that ALC was limiting output power. So unless I happened to notice, or someone local pointed out my wicked key clicks, I was unaware. Using TX inhibit, I get the same result of protecting the amp, but it happens in a more spectacular way with red fault indicators so I know the operator messed up. Not sure if ALC will shut down the exciter as well as TX inh if there's a jumper, feedline, tuner or antenna problem.

73,
Josh W6XU

Sent from my mobile device

> On Dec 21, 2017, at 10:18 AM, Dave Cole (NK7Z) <[hidden email]> wrote:
>
> Thank you for the information, however I just want to reduce the possibility of excessive voice peaks via ALC, not to do compression via ALC.
>
> We all make errors, and I would like to reduce the possibility of hitting the amp too hard on voice peaks in the event I miss adjust the K3 output level.
>
> 73s and thanks,
> Dave
> NK7Z
> http://www.nk7z.net
>
>> On 12/21/2017 09:56 AM, Josh wrote:
>> It creates garbage in your transmitted signal when ALC wiggles. If you keep drive power set low enough that ALC doesn't activate, it's okay.
>> Better option is to use the K3's xmit inhibit line if your amp supports it.
>> 73
>> Josh W6XU
>>

Josh Fiden

Re: ALC and the K3

In reply to this post by Don Wilhelm

That's a great feature. The problem I have is going from running without amp at 100W to driving amp and forgetting to reset levels. So human error (at least in my case) is easy and requires some protection. I also run 2 different 6m amps, one for terrestrial and another for EME, with different drive requirements. As noted I use tx inh with good result.

73
Josh W6XU

Sent from my mobile device

>
> The K3 has a menu setting (PWR SET) that can allow you to set the maximum power on a per-band basis. You can use that to avoid overdriving the amplifier.
>

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Joe Subich, W4TV-4

Re: ALC and the K3

In reply to this post by Bob McGraw - K4TAX

On 12/21/2017 2:34 PM, Bob McGraw K4TAX wrote:
> Just tune and load the amp for maximum output and then reduce drive
> power from the K3 to attain the level of power you desire to operate.

This assumes one has a (tube) amplifier with Tune/Load controls.

> If it is linear at 1500 watts, then reducing drive, it will be linear
> at 500 watts.

But *much less efficient*. The output network will be adjusted for
peak current/minimum voltage conditions of maximum output while the
typical (average) voltage/current will be much different.

> If one re-tweaks at lower power it most likely won't be linear at
> 1500 watts or any lesser peak there of.

While it will not be "linear" at power levels above the level at which
the output network was tuned, it will certainly be "linear" up to that
point *and much more efficient* (less loss in the output network).

73,

... Joe, W4TV

On 12/21/2017 2:34 PM, Bob McGraw K4TAX wrote:

> As a rule ALC is not needed and is not recommended by Elecraft. The K3
> power management system with the internal ALC is far superior to the
> derived voltage from most all amps. And, unlike many radios which when
> operated with reduced power, they do have a propensity to overshoot, the
> K3 series has firm ALC control at all power levels.
>
> Just tune and load the amp for maximum output and then reduce drive
> power from the K3 to attain the level of power you desire to operate.
> And as a note, after tuning and loading to maximum output, do not
> re-tweak the controls for or at the lower power operation. This is a
> common misunderstanding among hams. If it is linear at 1500 watts, then
> reducing drive, it will be linear at 500 watts. If one re-tweaks at
> lower power it most likely won't be linear at 1500 watts or any lesser
> peak there of. It will more likely be a "splatter generator".
>
> 73
>
> Bob, K4TAX
>
>
> On 12/21/2017 11:45 AM, Dave Cole (NK7Z) wrote:
>> I want to run ALC for my amp if for no other reason to protect the amp
>> from overpower events. I understand Elecraft does not recommend the
>> use of ALC...
>>
>> Exactly why is that?
>>
>
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

NK7Z

Re: ALC and the K3

In reply to this post by Don Wilhelm

Don,

Thank you for the information here... My amp, (the ALS-1306, solid
state), I believe does use the ALC to shut things down in the event of a
failure of some sort...

Here is a cut from the ALS-1306 blurb page:

"Output power is automatically reduced to prevent amplifier damage by
controlling ALC to exciter."

That does not tell me exactly what triggers ALC action, but it does tell
me that they are using ALC as a form of protection... As such I want to
use ALC.

I think I like your idea of adjusting the Amp to not issue ALC during
normal operation, that way, if something goes way wrong, the ALC may
still be able to shut things down. Fortunately the Amp has both
metered, and front panel adjustable ALC.

I think I will also adjust the Max power for all bands as well... I
just finished the install of the SWR/signal monitor thing-a-mabob in my
P3. I also have an outboard demod I built, which I can feed into the
scope to do a bit of monitoring during setup...

Too all the rest of the folks that made suggestions thank you as well!!

73s and thanks,
Dave
NK7Z
http://www.nk7z.net

On 12/21/2017 11:01 AM, Don Wilhelm wrote:

> Dave,
>
> The K3 does not overshoot due to the way output power is controlled (it
> is different than other amateur transceivers in that regard.
> So unless the amplifier contains protective circuits which activate the
> ALC for excessive SWR or other amplifier faults, there is no need to
> connect the ALC line. Even if the amp contains such protective
> circuits, adjust the ALC in the amp so it does not activate with normal
> operation.
> Set the power so the amplifier is not overdriven.
>
> If the ALC is activated in normal operation you will be creating
> excessive IMD in your transmit signal - you can hear a lot of that going
> on during a contest weekend.
>
> The K3 has a menu setting (PWR SET) that can allow you to set the
> maximum power on a per-band basis. You can use that to avoid
> overdriving the amplifier.
>
> 73,
> Don W3FPR
>
>
>
> On 12/21/2017 12:45 PM, Dave Cole (NK7Z) wrote:
>> I want to run ALC for my amp if for no other reason to protect the amp
>> from overpower events. I understand Elecraft does not recommend the
>> use of ALC...
>>
>> Exactly why is that?
>>

NK7Z

Re: ALC and the K3

Don, et al.,

I did a bit more reading on the Ameritron site, and on other forms, it
seems the 1306 only uses ALC for overpower, which the K3 can contain
with the adjustments you mentioned, so no need for the ALC cable!!

Thanks for letting me know about the menu sets for this. I had not run
across them, and I thought I had looked at every menu setting there!

73s and thanks,
Dave
NK7Z
http://www.nk7z.net

On 12/21/2017 12:23 PM, Dave Cole (NK7Z) wrote:

> Don,
>
> Thank you for the information here... My amp, (the ALS-1306, solid
> state), I believe does use the ALC to shut things down in the event of a
> failure of some sort...
>
> Here is a cut from the ALS-1306 blurb page:
>
> "Output power is automatically reduced to prevent amplifier damage by
> controlling ALC to exciter."
>
> That does not tell me exactly what triggers ALC action, but it does tell
> me that they are using ALC as a form of protection... As such I want to
> use ALC.
>
> I think I like your idea of adjusting the Amp to not issue ALC during
> normal operation, that way, if something goes way wrong, the ALC may
> still be able to shut things down. Fortunately the Amp has both
> metered, and front panel adjustable ALC.
>
> I think I will also adjust the Max power for all bands as well... I
> just finished the install of the SWR/signal monitor thing-a-mabob in my
> P3. I also have an outboard demod I built, which I can feed into the
> scope to do a bit of monitoring during setup...
>
> Too all the rest of the folks that made suggestions thank you as well!!
>
> 73s and thanks,
> Dave
> NK7Z
> http://www.nk7z.net
>
> On 12/21/2017 11:01 AM, Don Wilhelm wrote:
>> Dave,
>>
>> The K3 does not overshoot due to the way output power is controlled
>> (it is different than other amateur transceivers in that regard.
>> So unless the amplifier contains protective circuits which activate
>> the ALC for excessive SWR or other amplifier faults, there is no need
>> to connect the ALC line. Even if the amp contains such protective
>> circuits, adjust the ALC in the amp so it does not activate with
>> normal operation.
>> Set the power so the amplifier is not overdriven.
>>
>> If the ALC is activated in normal operation you will be creating
>> excessive IMD in your transmit signal - you can hear a lot of that
>> going on during a contest weekend.
>>
>> The K3 has a menu setting (PWR SET) that can allow you to set the
>> maximum power on a per-band basis. You can use that to avoid
>> overdriving the amplifier.
>>
>> 73,
>> Don W3FPR
>>
>>
>>
>> On 12/21/2017 12:45 PM, Dave Cole (NK7Z) wrote:
>>> I want to run ALC for my amp if for no other reason to protect the
>>> amp from overpower events. I understand Elecraft does not recommend
>>> the use of ALC...
>>>
>>> Exactly why is that?
>>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

K9MA

Re: ALC and the K3

Sometime back around 1970, I built an amplifier for my college radio
club. I spent many, many hours trying to get ALC to work, and failed
completely. Fortunately, the exciter really couldn't overdrive a pair
of 3-500Z's, so we ended up running it just as Elecraft recommends,
using only the exciter's internal ALC. I'm sure amplifier designers no
know a lot more about it than I did back then, but apparently closing
the ALC feedback loop around an external amplifier is still difficult to do.

73,
Scott K9MA

--
Scott K9MA

[hidden email]

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Bob McGraw - K4TAX

Re: ALC and the K3

As I understand and was taught, the amplifier ALC came about as the
result of exciters having the ability to excessively overdrive the
linear amp. Case and point, the Collins 32S1 transmitter would produce
about 150 watts output when correctly tuned and loaded. That was about
twice the required power to drive the matching 30L1 amplifier. Many
ask, why not just turn the power down? Well the 32S1 is a tube
transmitter which has lowest IMD and best efficiency when tuned and
loaded to the correct value. In order to prevent overdrive of the 30L1
amp, the amp ALC signal was fed back to the 32S1 to reduce the power to
the correct level via the intermediate stages , while the tuning of the
exciter PA, 32S1, remained correct. And thus today we do have amps
which have the ability to provide ALC back to the exciter.

It is of note that many modern day transceivers have ALC circuits which
do prevent overshoot at rated output. Unfortunately some of these, when
operated at less than rated output, have a faulty ALC system which does
briefly allow ALC overshoot. Using ALC from the amp back to the
exciter has been found not to be successful in controlling this
overshoot issue as the control element is too far down stream in the
system. Just look at the spectrum of many signals using an SDR receiver
and spectrum display. You'll observe a bit of splatter on the first
word or syllable of many signals. This is attributed to ALC overshoot
in the respective transceiver causing brief over drive of the amplifier.

73

Bob, K4TAX

On 12/21/2017 3:13 PM, K9MA wrote:

> Sometime back around 1970, I built an amplifier for my college radio
> club. I spent many, many hours trying to get ALC to work, and failed
> completely. Fortunately, the exciter really couldn't overdrive a pair
> of 3-500Z's, so we ended up running it just as Elecraft recommends,
> using only the exciter's internal ALC. I'm sure amplifier designers
> no know a lot more about it than I did back then, but apparently
> closing the ALC feedback loop around an external amplifier is still
> difficult to do.
>
> 73,
> Scott K9MA
>

Bill K9YEQ

Re: ALC and the K3

In reply to this post by NK7Z

Dave, I had an ALS-600. I sold it as I was buying up to a THP-2.5 1.5KW amp. The 600 lasted in the hands of the next buyer for less than a year. The THP was fantastic and I sold it before the purchase of the KPA500. I was concerned about repairing it with the company out of business and it didn't always fault in the condx you mentioned. While it was built to be cast iron, I did not want to take a risk. The KXPA500 amp is what I am using now and would like to come up with $'s to buy the KPA1500 in a flash because the 500 so easily corrects my errors in a flash, and I do make errors... wrong antennas, etc. It continues to function better than my previous two amps and shuts down in a flash if any of the two conditions you mention exist... including overdrive, wrong antenna or I screwed something else up. My post is to advise, you get what you pay for and newer technology exists to protect an amp. Love the 500 and will buy the 1500 when funds are available. I think the 500 is one of the best amps out on the market. Again, you get what you pay for and I would rely on the Elecraft brand before all others, esp., MFJ. MFJ exists in my shack for many devices but not for a SS amp, IMHO.

73,
Bill
K9YEQ

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Dave Cole (NK7Z)
Sent: Thursday, December 21, 2017 2:43 PM
To: [hidden email]
Subject: Re: [Elecraft] ALC and the K3

Don, et al.,

I did a bit more reading on the Ameritron site, and on other forms, it seems the 1306 only uses ALC for overpower, which the K3 can contain with the adjustments you mentioned, so no need for the ALC cable!!

Thanks for letting me know about the menu sets for this. I had not run across them, and I thought I had looked at every menu setting there!

73s and thanks,
Dave
NK7Z
http://www.nk7z.net

On 12/21/2017 12:23 PM, Dave Cole (NK7Z) wrote:

> Don,
>
> Thank you for the information here... My amp, (the ALS-1306, solid
> state), I believe does use the ALC to shut things down in the event of
> a failure of some sort...
>
> Here is a cut from the ALS-1306 blurb page:
>
> "Output power is automatically reduced to prevent amplifier damage by
> controlling ALC to exciter."
>
> That does not tell me exactly what triggers ALC action, but it does
> tell me that they are using ALC as a form of protection... As such I
> want to use ALC.
>
> I think I like your idea of adjusting the Amp to not issue ALC during
> normal operation, that way, if something goes way wrong, the ALC may
> still be able to shut things down. Fortunately the Amp has both
> metered, and front panel adjustable ALC.
>
> I think I will also adjust the Max power for all bands as well... I
> just finished the install of the SWR/signal monitor thing-a-mabob in
> my P3. I also have an outboard demod I built, which I can feed into
> the scope to do a bit of monitoring during setup...
>
> Too all the rest of the folks that made suggestions thank you as well!!
>
> 73s and thanks,
> Dave
> NK7Z
> http://www.nk7z.net
>
> On 12/21/2017 11:01 AM, Don Wilhelm wrote:
>> Dave,
>>
>> The K3 does not overshoot due to the way output power is controlled
>> (it is different than other amateur transceivers in that regard.
>> So unless the amplifier contains protective circuits which activate
>> the ALC for excessive SWR or other amplifier faults, there is no need
>> to connect the ALC line. Even if the amp contains such protective
>> circuits, adjust the ALC in the amp so it does not activate with
>> normal operation.
>> Set the power so the amplifier is not overdriven.
>>
>> If the ALC is activated in normal operation you will be creating
>> excessive IMD in your transmit signal - you can hear a lot of that
>> going on during a contest weekend.
>>
>> The K3 has a menu setting (PWR SET) that can allow you to set the
>> maximum power on a per-band basis. You can use that to avoid
>> overdriving the amplifier.
>>
>> 73,
>> Don W3FPR
>>
>>
>>
>> On 12/21/2017 12:45 PM, Dave Cole (NK7Z) wrote:
>>> I want to run ALC for my amp if for no other reason to protect the
>>> amp from overpower events. I understand Elecraft does not recommend
>>> the use of ALC...
>>>
>>> Exactly why is that?
>>>
> ______________________________________________________________
> 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 Message delivered to
> [hidden email]

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