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Re: [TCML] Some VTTC tube rolling results...got surprised twice!

Hi Andrew,

I have several methods that I use.

We are all different, but on VTTC's I don't like to mess with the primary
and feedback windings with taps. It changes the coupling to each other and
changes primary coupling to the secondary. This will also mess with the
grid leak circuit in my opinion affecting control.

I have a lot of control in my grid circuit.

Currently on this coil, I mentioned above in this thread that I currently
have a vacuum variable cap (second one now, switced to a wider range one)
used in conjunction with a fixed mica cap (that was picked with some rough
calculations as a starting point). And I have a "round" adjustable style
rheostat in the grid leak. I use these together for current tuning which is
very convenient for adjusting while running.

In the past I would just add or remove capacitance in the tank. I have a
large amount of micas caps to choose from (but still at times don't have
exactly what I need, that is also convenient to hook up). Can never have
enough micas :-)

Also have a good selection of toriod sizes to tune with and see what my
coil likes best. I consider this important. Related to this, I also
consider breakout point proper length according to the size of the toroid
currently used.

I will also not hesitate to strip off the wire on the secondary and rewind
it to get it to run in the area that I want to "tune in".  This current
secondary now has it's 3rd winding. This happens at times after trying
different toroids and from the streamer loading, that I notice that I am
out the "area".

Related, this current coil has now it's primary and feedback changed 3
times I think now. Turns are the same, but reconfigured to work better for

I have used fixed resistors in the grid in the past and I have have changed
values to tune.

Related, I will also change the grid leak capacitor to find what works best
for me.

Before I simplified the grid leak on this coil I had a selector switch
between 3 different grid leak caps. I would switch while running. I would
also change these 3 at times and again switch while running. Finally found
what I thought was best, then decided to simplify this circuit, not
necessary any more.

As you may see, I do not hesitate to make major changes if I feel it is
I am also willing to try completely different tubes experimenting again to
find what works best for me.

I will hook up alot of extra meters to monitor several things also.
Currently I have this simplified to just one critical meter in my opinion
and one other meter which is probably temporary.
I am confident now in how all is running.

At times, I will also scope things, to see were it is or if I am curious
about something that puzzles me.

I will make true measurements of inductances, capacitance, and resistance
of all components. This includes the secondary and primary.
I will also check the frequency of the secondary and the primary.

A lot of what I design for a coil is done in my head, just some basic
initial notes and I just start building slowly gathering up parts, using
existing parts I have,  start putting it together, change my mind during
this, make changes, continue building...

I think this covers the majority of what I do... currently tired after
work... sleep is calling soon... hope some of this makes sense, again very

Chris Reeland
Ladd Illinois USA

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