K3 strong signal handling

[Eric Scace K3NA]

Hi Wayne --

   I always get nervous when I see diodes proposed to clip strong RF.

   One of the biggest problems we have in a multi-transmitter site
(DXpedition or multi-TX contest station) is IMD generated by diodes
rectifying RF and re-radiating the result back into the local
environment.  Even a nearby AM BC station can induce enough voltage on
cause diodes to start rectifying.

    IMHO, if some guy wants to listen to a full-power signal from <100m
away, it is his responsibility to insert an appropriate external attenuator.

   I really don't want to see the performance of the K3 (AGC on or off)
compromised in any way whatsoever to handle such an atypical scenario.

73,
   -- Eric K3NA
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[WILLIS COOKE]

This whole big thread did not start with anyone demanding the K3 be modified so that we can talk to a guy in the driveway running full power.  We were discussing what we had observed and talking about remembering to turn off the pre-amp and turn on the attenuator when a person or two decided to call us stupid for discussing the issue.  Other people started talking about adding diodes and some ventured speculation that the pin diodes in the TR circuit might be contributing.  I am confident that Wayne and the others understand this and will not take any action that does not seem to improve the product.  

Wayne has recommended that I do the VCO mod on my K3 which I plan to do, but that is not a change to the product as that mod is in the current production units.  

It sure is easy to get a war started on this reflector by trying to have an ordinary dialog about how to use the product a little more intellegently.

Willis 'Cookie' Cooke
K5EWJ


--- On Tue, 5/5/09, Eric Scace K3NA <[hidden email]> wrote:

> From: Eric Scace K3NA <[hidden email]>
> Subject: [Elecraft] K3 strong signal handling
> To: "Wayne N6KR" <[hidden email]>
> Cc: "Elecraft mailing list" <[hidden email]>
> Date: Tuesday, May 5, 2009, 8:24 PM
> Hi Wayne --
>
>    I always get nervous when I see diodes proposed to clip
> strong RF.
>
>    One of the biggest problems we have in a
> multi-transmitter site
> (DXpedition or multi-TX contest station) is IMD generated
> by diodes
> rectifying RF and re-radiating the result back into the
> local
> environment.  Even a nearby AM BC station can induce enough
> voltage on
> cause diodes to start rectifying.
>
>     IMHO, if some guy wants to listen to a full-power
> signal from <100m
> away, it is his responsibility to insert an appropriate
> external attenuator.
>
>    I really don't want to see the performance of the K3
> (AGC on or off)
> compromised in any way whatsoever to handle such an
> atypical scenario.
>
> 73,
>    -- Eric K3NA
> ______________________________________________________________
> 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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[wayne burdick]

On May 5, 2009, at 8:40 PM, WILLIS COOKE wrote:

>
> This whole big thread did not start with anyone demanding the K3 be
> modified so that we can talk to a guy in the driveway running full
> power.  We were discussing what we had observed and talking about
> remembering to turn off the pre-amp and turn on the attenuator when a
> person or two decided to call us stupid for discussing the issue.  
> Other people started talking about adding diodes and some ventured
> speculation that the pin diodes in the TR circuit might be
> contributing.  I am confident that Wayne and the others understand
> this and will not take any action that does not seem to improve the
> product.

Absolutely!

>
> Wayne has recommended that I do the VCO mod on my K3 which I plan to
> do, but that is not a change to the product as that mod is in the
> current production units.

Wayne

---

http://www.elecraft.com

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