[AMPS] SB-220 input circuit

[Tom Rauch]

> €  In the SB-220, the input pi-network has a Q of somewhat less than two. 
>  For a solid-state radio, a Q of c. two is needed to obtain a good match.

It doesn't make any difference what the source is, transistor or 
tube, in setting SWR.

SWR is set only by the load impedance, and the impedance of the 
line to that load.

If I adjust an input network for a SWR of 1:1, I can replace the 
driver with any type of driver (as long as it doesn't have strong 
spurious emissions) and SWR will remain 1:1.

Minimum Q to match two systems, and still have the network 
behave as a pi is one plus the sqrt of Z1/Z2. Where Z1 is the higher 
impedance of the two. Less Q than that can be used, if the network 
phase shift is allowed to approach 90 degrees.




 
73, Tom W8JI
w8ji@contesting.com

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