----- Original Message -----
From: "Jim Brown" <jim@audiosystemsgroup.com>
>
> So you say, go with the bridges. BUT: Grid current in the Titan
> tends to be much lower when the Titan bridge indicates zero
> reflected power, and rises rapidly when I don't. And grid current
> is the big NO-NO in 3CX800A7's, the output tubes in the Titan. I am
> careful to keep grid current down to an indicated 30 mA for the
> pair (120 mA is absolute max). I can't get close rated power
> without excessive grid current unless I tune the antenna for zero
> reflected indicated on the Titan.
>
Hi Jim,
Are you sure that you have done due diligence twiddling the
amplifier load and tune controls with a zero reflected power
reading on the external Bird meter (higher VSWR reading on
Titan meter). Even if the amplifier output tank is really seeing
a 1.5:1 or 2.0:1 VSWR when the Bird meter reads zero
reflected power, you should be able to compensate for that
with careful adjustment of the load and tune controls. At
least that's been my experience with other amplifiers I've used
(no experience with the Titan). Also, don't forgot that the
FWD power reading on the Bird will be about 10% higher
for the same output power when it sees a 2.0:1 VSWR as
compared to 1:1 VSWR (e.g. don't be fooled into thinking
you are getting more Pout when the tuner is set for a 2.0:1
reading on the Bird and a 1:1 reading on the Titan as compared
to the inverse case). IOW, it would make more sense if this
was just a meter problem rather than a actual impedance
transformation between the amplifier output and the tank
output (e.g. amp output see 2.0:1 but tank output sees 1:1).
73, Mike W4EF................
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