[Elecraft] Balanced AT

[David Cutter]

Whatever happened to "silent tuning?"  I know it's not entirely silent, but 
monitoring across a dummy load with a bridge circuit means the auto 
tuner/matcher can sniff the incoming rf and adjust for best match/tune and 
then switch to full connection.  On most HF bands, say >20m, there might be 
only one optimum point in the middle of each sub-band, so re-tuning/matching 
would not delay things by much.

David
G3UNA


----- Original Message ----- 
From: "Jack Brindle" <jackbrindle at earthlink.net>
To: "Elecraft Discussion List" <elecraft at mailman.qth.net>
Sent: Sunday, September 09, 2007 4:15 AM
Subject: Re: [Elecraft] Balanced AT


> 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
> ------------------------------------------------------------------------ 
> ---------------------
>
>
> _______________________________________________
> 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