John,
I have one of those Henry Ultra Amplifiers and I didn't think it was that
difficult to tune up. I do have the pre-sets and that does make it pretty
easy to tune as long as you are tuning to the band the pre-set is set up
for.
I think that using the guide that Henry sent with the manual for each band
really give you a good base line to start from and I have always found it
easy to tune from there.
The last 3K Ultras that rolled off the line did have the up graded 26 volt
relay supply and the different input circuit and I have not found a manual
that reflected those changes.
Bob, if John doesn't get you a copy of the manual, I could make a copy of my
manual and mail it to you. I think I have one of the latest copies from Ted
and Paul at Henry but it really doesn't show everything that is in the last
version.
73,
Pat W1KA
----- Original Message -----
From: <JMLTINC@aol.com>
To: <amps@contesting.com>
Sent: Thursday, November 22, 2007 7:44 AM
Subject: Re: [Amps] Amplifier with Remote Capability
> Hi Bob,
>
> IMO, The Henry 3K Ultra is a poor example for remote control to follow. I
> own one of these amplifiers, and it is a pain to tune - unless you use
> the
> presets.
>
> The problem is the archaic circuitry to achieve remote control.
> Ultimately,
> it come down to lack of proportional control. Picture this:
>
> Both Load and Tune controls (knobs) on the Control Deck are shafted to a
> 10-turn potentiometer. At the RF deck, the tune coils and the load cap
> are
> turned via chain by DC gear motors. Each gear motor also turns a 10-turn
> pot (also
> via chain). The wipers of the two 10-turn pots are sent to a split
> voltage
> comparator (741). When the two pots are the same value, the comparator
> has 0 V
> output. When you turn a potentiometer on the Control Deck, the 741
> becomes
> unbalanced and either outputs a positive or negative (with respect to
> chassis
> ground) depending upon which way you rotate the pot. A classic H-Bridge
> relay
> circuit provides power and direction to the motor(s). The 741 remains
> unbalanced until the pot shafted to the motor catches up.
>
> A very simple plan to implement, but hard to use in practice. Suppose you
> are tuning up with no idea of where the controls should be - you aren't
> even in
> the ball park. You turn a Load or Tune control and watch the meters.
> Nothing
> seems to happen, or it does not happen fast enough because the gear
> motors
> turn at one, slow speed - like a slug. If you have turned the control too
> far,
> the gear motor will continue on, to catch up with your setting. So, to
> compensate, you turn the control the opposite way, ultimately
> overshooting where
> the motor currently is, and so the motor now reverses again. Trying to
> get the
> motor to stop on a dime is an impossible process.
>
> The only way to load and tune with any control over the motor is to bump
> the
> Tune or Load control a bit at a time and wait for the motors to catch up.
> The whole time the tube is groaning.
>
> The Henry 3K Ultra has an option for Presets. This is basically more
> 10-turn
> pots (one for each Load and Tune preset) that is switched in place of the
> manual, front panel Load and Tune controls. This is very effective once
> set.
>
> So, if you are looking for predetermined (preset) settings, the Henry
> approach is an easy alternative (although the cost of 10-turn pots may
> become
> excessive). If you are looking for a remoted manual-tuned amplifier a
> PIC/stepper
> motor-controlled solution ala the EZ-Tuner by W8ZR may be the answer.
>
> In any event, I have schematics for the 3K Ultra I can scan and email to
> you
> if you so desire. Contact me of list.
>
> -John, N9RF
>
>
>
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