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

[Elecraft mailing list]

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.
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