[Elecraft] 2 radios, 1 antenna... finally a prototype!

JEAN-FRANCOIS MENARD jfmenard at mac.com
Sat Nov 19 21:52:35 EST 2005


I know Vic. Another way to do it, will be to supply both relays to  
receive. So if no Amp key present or no 12V, or... By default, it  
could be connected to a dummy load....

There are many ways to do this, with different danger level....

Le 05-11-19 à 21:40, Vic K2VCO a écrit :

> JEAN-FRANCOIS MENARD wrote:
>
>> I finally did a first prototype of an interface to link two K2/ 
>> KPA100  on one multi-band HF antenna using Don W3FPR schematic.  
>> For my first  "from scratch" project, it is not too bad.
> <snip>
>> Take a look... http://homepage.mac.com/jfmenard/PhotoAlbum55.html
>
> The only thing that bothers me about this circuit is that if the  
> Amp Key output from either K2 is disconnected for any reason,  
> transmitting on the other one will put RF into the front end of the  
> first one.
>
> I thought of several ways to make the circuit fail-safe with a few  
> logic gates, but I'll leave it to the real circuit designers to  
> suggest the best way.  I would suggest using the 8r signals from  
> the K2s in addition to the amp-key output.  The 8r is on in receive  
> mode, and you could arrange things so that unless either an 8r  
> signal or amp-key ground is present, that K2 will always be  
> connected to the dummy load.
>
> -- 
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco



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