[Amps] Amplifier with Remote Capability

[Pat Poirier]

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 at aol.com>
To: <amps at 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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