[Elecraft] amp and coupler questions

[Pete Goudreau]

Lyle Johnson wrote:

> Hello Peter!

> I wouldn't depend on the AT-11, or any antenna matching system, to
> provide harmonic suppression for your system. The output from the
> transmitter should be clean, properly filtered, etc. The matching
> system should do just that -- match the transmitter to the load -- 
and
> nothing else.

Yep, I've come to the same conclusion, amazing what difference a day 
can make.

After thinking about the idea of using diode switching as well, it 
occurs to me that maybe adding BPFs between the K2 and the PA might 
not be a bad idea either in order to avoid distortion products from 
high power signals getting to the rx input through the switch diodes. 
 Wouldn't be cheap to do though but might be worth it.  Then again, a 
vacuum relay would be easier to use and less hassle since I wouldn't 
use full break-in QSK anyway.

> So figure several filters and some switching arrangement on the 
output
> of your AN-762 amplifier. AT least you can rest assured that the
> filters will be properly terminated into 50 ohms!

True enough.  Trick is figuring out a simple design for the 
bandswitching and perhaps an automatic switching method to avoid 
xmiting into the wrong filter.  Getting the band information out of 
the K2 doesn't seem possible as far as I can tell from studying the 
schematic.

Thanks and 73,
Pete, AD5HD