Hi all,
Been a while since any updates on this project of mine.
I have gotten busy on so many different things and hopefully will get back
on track on this soon.
Going to share some occasional pictures I took a while back during initial
construction and some recent pictures of it as it is now. Some things could
possibly change when I do again move forward on this.
I have decided on several changes already as can be seen in pictures.
I will no longer be using a main variac on the plate supply transformer.
I will use a temporary external variac during first light though...then if
all well...and if initial tuning is good enough for now...it will be
removed.
This will save 11.34 lbs on 120V in/out variac originally planned.
I have found a near perfect for the 304 tube, a 5V CT (2.5V CT 2.5V)@ 30A
Stancor NOS filament transformer at a Hamfest unexpectedly earlier this
year. This is very hard to find. Previous one was a 12V@16A Triad control
transformer set with a small variac for 10V. For those wondering now...the
304 is a weird tube in many ways. This single tube is actually four 75T's
in one. Four filaments total wired in pairs internally. There is four
filament pins on the base. These four pins can be wired parallel (5V@25A)
or series (10V@12.5A). The Triad was the closest I could find back then
and is a little bit overkill. A 10V filament transformer near those amps is
hard to find also. Going to save some weight here now...the Stancor @ 5.71
lbs vs. the Triad @ 8.03 lbs.
I will still control filament voltage with a small variac to avoid current
inrush to be nice to my four filaments and to better set proper required
filament voltage accurately. And this variac is going to change also thanks
to another Hamfest find...found a smaller one @ 1.63 lbs vs. 2.98 lbs of
the previous.
I am also going to replace the "sort of big" older Advance MOT @12.47 lbs.
This one is still much better than the "newer" MOT's. At least has some
more "iron" and has real copper wire (not copper plated aluminum wire).
Though, it still is not that great (still better than "newer") at "idle"
current.
At no load idle current it is 5.18 A and it does get quite warm after
awhile.
My "new" plate duty transformer is an "even bigger looking MOT", but it is
not one actually. This is a Canatron @15.58 lbs, made in the UK, found on
eBay in the USA. Seller said it was removed from an older Varian ion pump
power supply. The build quality looks much better vs. older and newer
MOT's, which is expected. I would say also that a much higher quality grade
of lamination steel is being used here also. This fella is going to add a
little weight to my project...but is worth it. And I have already saved
weight in other areas. A no load idle current check shows 0.15A...ahh
:^)...so much better!!! And of course stays cool after awhile leaving on,
unlike the old MOT. (Just for a comparison...the NOS Stancor fil. trans. at
idle is 0.13A)
I am also going to get a voltage boost from this Canatron. Nameplate says
2600V and has multiple input taps. I will be using the 117V tap input.
Checking with no load, with my Sensitive Research electrostatic voltmeter
with 123V input (voltage at the time here), got an expected higher voltage
of just under 2800 V. For comparison, the old Advance MOT (nameplate does
not give output) I got 2125V no load.
I will also on this Canatron once again be utilizing a lever shifter and I
will take FULL advantage of the longer "ramp" this waveform offers in
addition to the even more voltage this offers of course, with my several
Interrupter/Staccato controllers I have.
I have decided on the replacement for the original secondary acrylic tube.
I am going to try a piece of G10 thin wall tube that found. Got the new
wire already, so hopefully will wind this soon.
Okay...I think I covered "most" things here on this update finally...I will
let pictures cover the rest...ask if curious on other things and I will try
to answer...I am still working out several other things on the top deck in
my head, got most of it so far...
Here is the pictures link:
https://photos.app.goo.gl/UCR5hZdTnVttPbVKA
Chris Reeland
Ladd Illinois USA
Sent from my Samsung Galaxy Tab® S