[Elecraft] Balanced AT

[Jack Brindle]

While such a tuner might be fun to work with, it would unfortunately  
have a very short life due to burnout of the relay contacts when  
tuning at full power. There are also very high voltages created for  
various combinations of L and C while tuning is going on, which would  
undoubtedly shorten the life of the other components.

For such a tuner to work, it would need the ability to have the  
exciter drop to low power while tuning, then return to full power  
when the tuning task is done. This is far worse than telling the  
tuner before transmission occurs the frequency for operation.

Note that this same situation exists whether the tuner needs to tune  
for each transmission or it has frequency memories. Quite simply, the  
problem is switching the relays at full power.

My belief is that the best way to handle the situation is to  
communicate the operating frequency to the tuner so it can use its  
memories, or to send the actual relay settings whenever they need to  
change. Of course, this should be done during receive, when no power  
is applied. This is the method used in the K2 tuners, and I am sure  
Wayne is also doing it in the K3 ATU.

It's awfully hard to do in a remote tuner, although perhaps the best  
example is the method used in tuning the Steppir (which uses  
frequency data from the radio).


On Sep 7, 2007, at 9:08 AM, Edward Dickinson, III wrote:

> ...remote tuners is for a tuner that tunes itself for a match and  
> which does
> not require to be given band data from the rig. ...
>
> 73,
> Geoff
> GM4ESD
> -----------------------
> Hi Greg.
>
> I support your notion.
>
>
> Regards,
> Dick - KA5KKT/4
>
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

- Jack Brindle, W6FB
------------------------------------------------------------------------ 
---------------------