[R-390] R-390A balanced input question

[Tisha Hayes]

If you use the balanced input you can go through and trim up the 1st RF
stages. Make sure you use the same hook-up that you are going to run with.
In other words, if you are doing the "one pin shorted to ground, the other
attached to a 50 ohm coax" that you calibrate with that connection.

If you use a balun (2.25:1 or 2:5:1) then you need to do the alignment
through that connection. Make sure you set the ANT-TRIM knob to the center,
neutral position when doing the alignment on the RF stages. Otherwise you
will peak that stage with some skewed capacitance tossed on top of things.

You are peaking performance. Usually I shoot for the middle of the band
that is associated with that RF stage. Since I use one of the German-made
baluns I do the  alignment from a 50 ohm unbalanced connection from my
signal generator, through the balun, through the unbalanced connection and
the 1st RF..

The reason I suggest this is that the 1st RF stage was probably pretty
close to the 125-150 ohm balanced impedance. Unless someone screwed with it
when they were actually using the C connection and that 1st RF stage was
bypassed.

-- 
Ms. Tisha Hayes. AA4HA

*""It is not because things are difficult that we dare not venture. It is
because we dare not venture that they are difficult." -Seneca"*