[BC] AM Loads

[Alan Alsobrook]

Ronald J. Dot'o Sr. wrote:
>In the past I've adjusted the ATU with a bridge to a 50 ohm, 0J 
>match but the TX didn't like it when I applied power, as I guess 
>things change under full power, so I adopted this method which 
>doesn't require the test equipment and works for me.

On a single tower (Non-D) station, you should NOT be seeing such a 
difference from the bridge. One (or more) things must be happening.

A. Transmitter output is not 50j0. Some of the boxes seem to like a 
slightly capacitive load. Component failure can cause output network 
mismatch. (have an Omni that only likes 41 -j14 due to bad chip caps)

C. Bridge leads are introducing too much inductance, (this shouldn't 
be a problem at a 50j0 point)

D. Bridge is not calibrated, this is easily verified by measuring a 
known 50j0 ohm resistor, other values can be checked as well.

E. Someone overlooked a range shifting switch in the wrong position. 
(Of course I've never done that myself..)

F. Something is just really screwed up!

-- 
Alan Alsobrook CSRE AMD CBNT
St. Augustine Fl. 32086 904-829-8885
aalso at Bellsouth.net