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Using A 6 Meter LNA & Amplifier with the K3S

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stengrevics

Using A 6 Meter LNA & Amplifier with the K3S

I am installing an LNA at the feed point of my 6 meter antenna. I also drive a W6PQL amplifier.

My reading of the manual, and Fred Cady’s book, suggests that no external ALC is necessary to protect the LNA. Can someone using a similar set-up confirm this? Or, suggest a procedure to follow if my interpretation is incorrect?

Thanks,

John
WA1EAZ
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stengrevics

Re: Using A 6 Meter LNA & Amplifier with the K3S

My apologies - I should have added that I am using a Downeast Microwave DTR relay to take the LNA out of the line when voltage applied to the relay drops as a result of transmission.

73,

John
WA1EAZ
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Don Wilhelm

Re: Using A 6 Meter LNA & Amplifier with the K3S

John,

I do not understand how the amplifier or the ALC could protect the LNA.
I assume the LNA is only used on receive, so if you have good sequencing
between receive and transmit, no damage could occur.
ALC is only applicable to transmit, and Elecraft does not recommend
using ALC to limit the drive to the amplifier. Set the power to the amp
properly and all will be well.
Using ALC to control the exciter power is a bad way to do things, it
will only lead to distortion and spurious emissions from the amplifier.

73,
Don W3FPR

On 9/23/2018 10:58 AM, John Stengrevics wrote:
> My apologies - I should have added that I am using a Downeast Microwave DTR relay to take the LNA out of the line when voltage applied to the relay drops as a result of transmission.
>
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stengrevics

Re: Using A 6 Meter LNA & Amplifier with the K3S

Hi Don,

That was timely as I just got off Skype with Jim, W6PQL. He mentioned that the ALC should be held high for some milliseconds to allow for the amp’s relays to switch over thereby protecting the LNA.

Since the K3S works differently than most, he suggested that I look for an RF Hold-Off setting on the K3S and set it for around 50 milliseconds. That being said, I don’t see that in the manual or in Fred’s book. Any suggestions?

73,

John
WA1EAZ

> On Sep 23, 2018, at 11:12 AM, Don Wilhelm <[hidden email]> wrote:
>
> John,
>
> I do not understand how the amplifier or the ALC could protect the LNA.
> I assume the LNA is only used on receive, so if you have good sequencing between receive and transmit, no damage could occur.
> ALC is only applicable to transmit, and Elecraft does not recommend using ALC to limit the drive to the amplifier. Set the power to the amp properly and all will be well.
> Using ALC to control the exciter power is a bad way to do things, it will only lead to distortion and spurious emissions from the amplifier.
>
> 73,
> Don W3FPR
>
> On 9/23/2018 10:58 AM, John Stengrevics wrote:
>> My apologies - I should have added that I am using a Downeast Microwave DTR relay to take the LNA out of the line when voltage applied to the relay drops as a result of transmission.

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John Simmons

Re: Using A 6 Meter LNA & Amplifier with the K3S

I think it is called TX DELAY. I know the setting is in there.

-John NI0K

John Stengrevics wrote on 9/23/2018 10:29 AM:

> Hi Don,
>
> That was timely as I just got off Skype with Jim, W6PQL. He mentioned that the ALC should be held high for some milliseconds to allow for the amp’s relays to switch over thereby protecting the LNA.
>
> Since the K3S works differently than most, he suggested that I look for an RF Hold-Off setting on the K3S and set it for around 50 milliseconds. That being said, I don’t see that in the manual or in Fred’s book. Any suggestions?
>
> 73,
>
> John
> WA1EAZ
>
>> On Sep 23, 2018, at 11:12 AM, Don Wilhelm <[hidden email]> wrote:
>>
>> John,
>>
>> I do not understand how the amplifier or the ALC could protect the LNA.
>> I assume the LNA is only used on receive, so if you have good sequencing between receive and transmit, no damage could occur.
>> ALC is only applicable to transmit, and Elecraft does not recommend using ALC to limit the drive to the amplifier. Set the power to the amp properly and all will be well.
>> Using ALC to control the exciter power is a bad way to do things, it will only lead to distortion and spurious emissions from the amplifier.
>>
>> 73,
>> Don W3FPR
>>
>> On 9/23/2018 10:58 AM, John Stengrevics wrote:
>>> My apologies - I should have added that I am using a Downeast Microwave DTR relay to take the LNA out of the line when voltage applied to the relay drops as a result of transmission.
> ______________________________________________________________
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stengrevics

Re: Using A 6 Meter LNA & Amplifier with the K3S

Hi John,

Aha! I see that now. OK, I will follow the instruction in Fred’s book to set this.

Thanks & 73,

John
WA1EAZ

> On Sep 23, 2018, at 11:53 AM, John Simmons <[hidden email]> wrote:
>
> I think it is called TX DELAY. I know the setting is in there.
>
> -John NI0K
>
> John Stengrevics wrote on 9/23/2018 10:29 AM:
>> Hi Don,
>>
>> That was timely as I just got off Skype with Jim, W6PQL. He mentioned that the ALC should be held high for some milliseconds to allow for the amp’s relays to switch over thereby protecting the LNA.
>>
>> Since the K3S works differently than most, he suggested that I look for an RF Hold-Off setting on the K3S and set it for around 50 milliseconds. That being said, I don’t see that in the manual or in Fred’s book. Any suggestions?
>>
>> 73,
>>
>> John
>> WA1EAZ
>>
>>> On Sep 23, 2018, at 11:12 AM, Don Wilhelm <[hidden email]> wrote:
>>>
>>> John,
>>>
>>> I do not understand how the amplifier or the ALC could protect the LNA.
>>> I assume the LNA is only used on receive, so if you have good sequencing between receive and transmit, no damage could occur.
>>> ALC is only applicable to transmit, and Elecraft does not recommend using ALC to limit the drive to the amplifier. Set the power to the amp properly and all will be well.
>>> Using ALC to control the exciter power is a bad way to do things, it will only lead to distortion and spurious emissions from the amplifier.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 9/23/2018 10:58 AM, John Stengrevics wrote:
>>>> My apologies - I should have added that I am using a Downeast Microwave DTR relay to take the LNA out of the line when voltage applied to the relay drops as a result of transmission.
>> ______________________________________________________________
>> 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
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Don Wilhelm

Re: Using A 6 Meter LNA & Amplifier with the K3S

In reply to this post by stengrevics

John,

There is TX Inhibit that will prevent RF from the K3 until that signal
is dropped.
Of course, it requires a signal from the amplifier or sequencer to
indicate that it is ready for RF.

Trying to use ALC for that purpose is not a good idea.
Does the amplifier control the high on ALC, or is that left to the
exciter to implement?

73,
Don W3FPR

On 9/23/2018 11:29 AM, John Stengrevics wrote:

stengrevics

Re: Using A 6 Meter LNA & Amplifier with the K3S

Hi Don,

Ordinarily, the W6PQL amp’s control board does this via ALC on the exciter. But, since that is not an option with the K3S, setting TX DELAY on the K3S to 20 milliseconds should do the trick. That is what Jim, W6PQL, suggested I do.

I have been using the W6PQL amp with the K3S without any problems heretofore.

73,

John
WA1EAZ

> On Sep 23, 2018, at 12:17 PM, Don Wilhelm <[hidden email]> wrote:
>
> John,
>
> There is TX Inhibit that will prevent RF from the K3 until that signal is dropped.
> Of course, it requires a signal from the amplifier or sequencer to indicate that it is ready for RF.
>
> Trying to use ALC for that purpose is not a good idea.
> Does the amplifier control the high on ALC, or is that left to the exciter to implement?
>
> 73,
> Don W3FPR
>
> On 9/23/2018 11:29 AM, John Stengrevics wrote:
>> Hi Don,
>>
>> That was timely as I just got off Skype with Jim, W6PQL. He mentioned that the ALC should be held high for some milliseconds to allow for the amp’s relays to switch over thereby protecting the LNA.
>>
>> Since the K3S works differently than most, he suggested that I look for an RF Hold-Off setting on the K3S and set it for around 50 milliseconds. That being said, I don’t see that in the manual or in Fred’s book. Any suggestions?
>>
>> 73,
>>
>> John
>> WA1EAZ
>>
>>> On Sep 23, 2018, at 11:12 AM, Don Wilhelm <[hidden email]> wrote:
>>>
>>> John,
>>>
>>> I do not understand how the amplifier or the ALC could protect the LNA.
>>> I assume the LNA is only used on receive, so if you have good sequencing between receive and transmit, no damage could occur.
>>> ALC is only applicable to transmit, and Elecraft does not recommend using ALC to limit the drive to the amplifier. Set the power to the amp properly and all will be well.
>>> Using ALC to control the exciter power is a bad way to do things, it will only lead to distortion and spurious emissions from the amplifier.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 9/23/2018 10:58 AM, John Stengrevics wrote:
>>>> My apologies - I should have added that I am using a Downeast Microwave DTR relay to take the LNA out of the line when voltage applied to the relay drops as a result of transmission.
>>
>

Jim Brown-10

Re: Using A 6 Meter LNA & Amplifier with the K3S

In reply to this post by Don Wilhelm

On 9/23/2018 8:12 AM, Don Wilhelm wrote:
> Using ALC to control the exciter power is a bad way to do things, it
> will only lead to distortion and spurious emissions from the amplifier.

RIGHT! The ONLY good use of ALC between rig and amp is to protect the
amp from a failure in the antenna system. To do that, set output power
from the rig to get the desired output level.

73, Jim K9YC

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ANDY DURBIN

Using A 6 Meter LNA & Amplifier with the K3S

In reply to this post by stengrevics

"The ONLY good use of ALC between rig and amp is to protect the amp from a failure in the antenna system. "

The KPA500 doesn't work that way so I'd be surprised if the KPA1500 did. For the KPA500 a badly mismatched load will trip the reflected power fault without making any change to the ALC voltage. I know this because ALC voltage is included in my logger data set and I have several logger records for Fault 09. (It's not that I'm really careless about antenna switching. FL09 was a deliberate test case for evaluating a KPA500 firmware defect.)

73,

Andy k3wyc
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Jim Brown-10

Re: Using A 6 Meter LNA & Amplifier with the K3S

On 9/23/2018 1:35 PM, ANDY DURBIN wrote:
> The KPA500 doesn't work that way so I'd be surprised if the KPA1500 did.

Some amps have more protection than others. Some have none. :)

73, Jim K9YC

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Elecraft mailing list

Re: Using A 6 Meter LNA & Amplifier with the K3S

In reply to this post by stengrevics

Hi John,

The acc cable is used to convey the control signal from the sequencer to
the K3 so that the TX INH will inhibit the K3 when configured correctly
and can be used whether or not the band is built in or not. It may be
possible to use the ALC output from the sequencer dependent upon its
level and polarity but I do not know how that is configured. If you
read the section in the manual that describes the inhibit and compare it
with the sequencer output you should be able to arrange it correctly.

73

Peter

G3SMT

On 23/09/2018 22:03, John Stengrevics wrote:

> Hi Peter,
>
> I appreciate what you are saying, but I have no use for an ACC cable. The K3S has 6 meters built in.
>
> I am using the W6PQL amp with the control board. But, the control board has to connect to ALC on the transceiver. The K3S has no ALC jack.
>
> I have asked Jim, W6PQL, if setting the TX DELAY to 20 milliseconds will provide enough time for relays to switch.
>
> 73,
>
> John
> WA1EAZ
>
>> On Sep 23, 2018, at 5:58 PM, Peter Torry <[hidden email]> wrote:
>>
>> Hi John,
>>
>> Pin 7 of the Acc connector is the transmit inhibit input that is enabled in the config menu. That is the only way to ensure that the K3 remains in Rx until the sequencer has completed its cycle. I use this with all my transverters and LNAs to ensure their correct sequencing.
>>
>> It is described in both the manual and the F Caddy book.
>>
>> As you are using the PQL amplifier I assume that you are also using the PQL control board V6 that has an output that may be used for this purpose, just check the polarity of the output as it may need inverting.
>>
>> Good luck with your project
>>
>> 73
>>
>> Peter
>>
>> G3SMT
>>
>>
>>
>> On 23/09/2018 19:54, John Stengrevics wrote:
>>> Hi Peter,
>>>
>>> Thanks for the reply. But, what would I be using an ACC cable for?
>>>
>>> 73,
>>>
>>> John
>>> WA1EAZ
>>>
>>>> On Sep 23, 2018, at 3:41 PM, Peter Torry <[hidden email]> wrote:
>>>>
>>>> Hi John,
>>>>
>>>> I agree with Don's comments as I use a K3 with an amplifier and an LNA in a similar configuration to yourself. I would never use ALC under any circumstances to avoid radiating a poor signal. To protect the LNA I use a signal from the sequencer in the amplifier to inhibit the K3 from transmitting until the sequencer has done its stuff. Setting the delay on the K3 still leaves you at risk as 20ms is too short a time for all the relays to operate satisfactorily. Use pin7 on the acc connector as detailed in the manual on transverter control - TX INH.
>>>>
>>>> 73
>>>>
>>>> Peter
>>>>
>>>> G3SMT
>>>>
>>>>
>>>> On 23/09/2018 15:29, John Stengrevics wrote:
>>>>> Hi Don,
>>>>>
>>>>> That was timely as I just got off Skype with Jim, W6PQL. He mentioned that the ALC should be held high for some milliseconds to allow for the amp’s relays to switch over thereby protecting the LNA.
>>>>>
>>>>> Since the K3S works differently than most, he suggested that I look for an RF Hold-Off setting on the K3S and set it for around 50 milliseconds. That being said, I don’t see that in the manual or in Fred’s book. Any suggestions?
>>>>>
>>>>> 73,
>>>>>
>>>>> John
>>>>> WA1EAZ
>>>>>
>>>>>> On Sep 23, 2018, at 11:12 AM, Don Wilhelm <[hidden email]> wrote:
>>>>>>
>>>>>> John,
>>>>>>
>>>>>> I do not understand how the amplifier or the ALC could protect the LNA.
>>>>>> I assume the LNA is only used on receive, so if you have good sequencing between receive and transmit, no damage could occur.
>>>>>> ALC is only applicable to transmit, and Elecraft does not recommend using ALC to limit the drive to the amplifier. Set the power to the amp properly and all will be well.
>>>>>> Using ALC to control the exciter power is a bad way to do things, it will only lead to distortion and spurious emissions from the amplifier.
>>>>>>
>>>>>> 73,
>>>>>> Don W3FPR
>>>>>>
>>>>>> On 9/23/2018 10:58 AM, John Stengrevics wrote:
>>>>>>> My apologies - I should have added that I am using a Downeast Microwave DTR relay to take the LNA out of the line when voltage applied to the relay drops as a result of transmission.
>>>>> ______________________________________________________________
>>>>> 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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Edward R Cole

Re: Using A 6 Meter LNA & Amplifier with the K3S

In reply to this post by stengrevics

Since this is for 6m which kind of considered VHF, then use of a
sequencer should be considered. With either K3 or K3S the last stage
of the sequencer can control TX INHIBIT control line of the K3/K3S
which will delay RF output into the PA until after LNA and TR relay
switching has occurred. W6PQL sells both an amplifier control board
with sequencing or separate sequencer:
http://www.w6pql.com/v63control.htm
http://www.w6pql.com/relay_sequencer.htm
or from DEMI:
http://01895fa.netsolhost.com/PDF/LTRS_PD.pdf

See: http://www.kl7uw.com/TX-INHIBIT.htm

73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[hidden email]

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stengrevics

Re: Using A 6 Meter LNA & Amplifier with the K3S

Thanks Ed, I have Jim’s control board in the amp. Just trying to figure out the connections.

John
WA1EAZ

> On Sep 24, 2018, at 2:46 AM, Edward R Cole <[hidden email]> wrote:
>
> Since this is for 6m which kind of considered VHF, then use of a sequencer should be considered. With either K3 or K3S the last stage of the sequencer can control TX INHIBIT control line of the K3/K3S which will delay RF output into the PA until after LNA and TR relay switching has occurred. W6PQL sells both an amplifier control board with sequencing or separate sequencer:
> http://www.w6pql.com/v63control.htm
> http://www.w6pql.com/relay_sequencer.htm
> or from DEMI:
> http://01895fa.netsolhost.com/PDF/LTRS_PD.pdf
>
> See: http://www.kl7uw.com/TX-INHIBIT.htm
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> Dubus-NA Business mail:
> [hidden email]
> ______________________________________________________________
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Jim Brown-10

Re: Using A 6 Meter LNA & Amplifier with the K3S

In reply to this post by Edward R Cole

On 9/23/2018 11:46 PM, Edward R Cole wrote:
> Since this is for 6m which kind of considered VHF, then use of a
> sequencer should be considered.

By definition, 6M is VHF, which is defined as 30-300 MHz.

The need TX delay/sequencing is related to relay switching times, NOT
operating frequency. The relationship to VHF/UHF has to do with slow
relays in equipment like power amps and mast-mounted preamps.

73, Jim K9YC

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