>The plate tune capacitor should be the LAST thing that you tune.
>It should also be the first thing that you tune.
>
>When you start out apply a small amount of drive and dip the plate with
>the plate tune cap. Or peak it for maximum output of the amp.
** For grounded-grid operation, peaking for max-out is somewhat better
because a fully-driven, fully loaded-tube has a very slight dip with a
Pi-tank.
- Starting with a lesser amount of drive is not useful since the settings
will be different at full throttle due to a different RL.
>Then
>increase the drive slightly and increase the loading for maximum output.
>Retune the plate tune again. You can do this in 3 stages as you mention,
>each time doing it with more drive until you get to full drive.
>
> You want to end up with full drive applied, tune plate tune for
>maximum output, tune load control for maximum output and then tune plate
>tune for maximum output again. If you get much of a change on the last
>retune of the plate tune then readjust the load control again and the
>plate tune again.
>
>By the way, keep one hand on the carrier level on the exciter as you are
>tuning up. Only insert carrier for the short time that you are actually
>turning the knobs. Then reduce the carrier until you get your other hand
>on the next knob to adjust. This way you will not have excess current in
>the amp for very long while it is not in tune.
** Very few Ham amplifiers have a HV supply that will not sag under a AØ
/ dead-carrier - thereby producing a mistune. The Henry 3K-A is one of
the few that has such a supply, however, it's 3-500Z cooling system is
not adequate for doing so (solder in pins 1 and 5 melts). // note - One
way to reduce average current during tuneup is to use a tuning pulser.
>
>
>It sounds like you are not loading the amp heavy enough and the plate
>circuit is arcing when you apply drive again.
>
>Are you turning the exciter on the second time with full carrier applied
>at turn on? If so the relays on the amp may not have enough time to
>connect the antenna before power is being generated causing arcing.
>
** Good point, which is why the relay in the SB-220 needs to be upgraded.
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