I use the Centurion amp, and noticed that the tune control has essentially no
effect on grid current, and the load control has no effect on almost anything,
except at very wide deviation from the recommended setting. I tune for maximum
out, and the grid current doesn't change enough to see any difference on the
internal meter. I can run the load control over most of its range without
changing the output power or the grid current. The SWR is generally very low -
less than 1.5 to 1 looking into the tuner. The load control does physically
move the load capacitor.
I guess I should be happy, since this simplifies tune up, but I'm concerned
that there may be something wrong. Does this indicate a problem?
73,
Frank
KF6E
-----Original Message-----
From: Dr. Gerald N. Johnson <geraldj@weather.net>
To: tentec@contesting.com
Sent: Wed, Nov 24, 2010 7:48 pm
Subject: Re: [TenTec] Titan 425 Initial Tune-Up settings - high VSWR
High swr seen by the exciter points to the cathode circuit tuning. It
may need to be adjusted if there are two input circuits for 80 and 75.
Typically the Q of that cathode tuned circuit is very low so it covers
the full band decently.
How are you tuning, for maximum out or by grid and plate currents?
Tuning by DC meters alone can get you a long ways from proper matching
and proper output. Tuning for maximum smoke out of the coax connector
gets the best results from a GG linear in my experience.
73, Jerry, K0CQ
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