The AM Forum

I needed a variac to turn down the plate voltage on the Gates BC-1J and this one became available at a good price. I just didn't realize how heavy it was; 54 lb shipping weight!

Now I just need a really cool large spoked knob to turn it!

240 vac in/0-280 vac out @ 28 amps; more than twice what I need, but it'll keep the plate supply stiff!

(http://img35.imageshack.us/img35/369/dscn3299m.th.jpg) (http://imageshack.us/photo/my-images/35/dscn3299m.jpg/)

When you post a picture with that high of resolution and size (over 4 megs), it will take forever for a slow DSL or dial-up to load if clicked on.

Cool Greg. I used resistors and never thought of this. Good luck and have fun.

Mike
www.w8bac.com (http://www.w8bac.com)

Mike,

I looked over your website and realized that I'd seen it before. I stole the idea of a 2x2 dummy to plan the move of the Gates into the basement; it cleared the side door by about 1/4 inch on either side and the top. I had to cut out the bottom step on the flight going to the second floor so I could turn the transmitter after I got it in the door. Same problem with finding a space between the joists to stand it up. I did add 4 heavy duty casters to the bottom plate such that the wheels only raise the cabinet off the floor about an inch. Mine was only about 300 lbs since I pulled all the units but the meter and relay panels and the wiring harness.

Hopefully I'll get the Gates on the air by next spring.

Greg

Fixed that!

Love the expression on the shat's face!

:-)

We're bigger Down Under.
Its the KW that counts.
That's a three phase device check the connector on top =440V X 15A X 3phase,
AND its still physically bigger than the three stacker.

Now this is big; a three stacker variac:

(http://home.comcast.net/~rburney6/controller.jpg)

I have a pair I ganged together for the ultimate amp project. I KNOW they weighed a lot more than 54# since I carried them to the car at Nearfest, Id say closer to 80# and they were just bare variacs with the wheels and voltage plates.

Another that Ive had for decades is just as heavy and is in use on the 6C21/304TL setup.

Carl

I think on the site that I pointed to, the writer said each one of the variacs weighed 74 pounds.

Nice looking cat.

I have three of the dual 28A units, all different.

One has two 240v sections and a fitting for a motor.

Another has both sections rated 120 or 240V but they are connected in parallel with an equalizing 'choke'. I am not sure why it would carry both voltage ratings. I use it in the workbench with a 7" handwheel.

One is labeled for 240/120 per section and has taps for same which I think is unusual. It also has a rheostat on the main shaft. It was used as an output control in a shaker table driver. The voice coil section is still in Chicago if anyone needs to make a giant subwoofer. It has a huge chrome hub with three radial hand bars and a hollow hub & shaft for a 1/4" concentric accessory, a 4" rheostat.

The major obstacle to using them horizontally is being able to support the rear of the unit. Most panels will bend.

They each weigh about 100 lbs +/-. None of them are as king size as those 3-phase ones.

That looks big enough for a 4CX5000A shaker or at least a pair of 4x1's

I like the "Automatic Electric" Bombay

Oil filled, too. ;)

73DG

I wound up mounting the pair individually bracketed on the rack cabinet base which is a pair of 3/4" hunks of plywood. There was still room for the 125# HV transformer, a 52.5uF 10KV,  125# oil filled, a couple of contactors and the diode/metering board along with various bleeders, overload relays, HV fuse, etc.

At least the rack wont be top heavy :o

That's inspiring.

How did you attach the wood or was it laid across? Do you have pictures?

A rack here has a metal floor but it is a little weak. I'm looking at 400# because the plate iron is old and I am using chokes.  2x6 planks are one thing I thought of, also bolting maybe a couple pieces of 1/8" thick 1x1" L angle across it next to where the weight is.

"Will it bend?"

The 1 1/2" thick plywood base is just laying on the rack floor which has HD sides but open in the middle for a large fan and that thinner sheet metal was bolted to the edge supports on each side and I added others front and rear. It was used for a 60's Sanders Data Systems 7' tall word processor. Ive tried to distribute the weight and there is no bowing yet. If I have to I'll fit center casters.

No pictures and Ive rolled it against a wall and have other junk up against it. I'll take photos as I do want to document this when I get at it again.

Does the little knob run a servo to turn the shaft and point to the voltage?

Ok that's what's basically here. tough rack rails and framing, thin gauge floor sheet supported at the edges by the lower frame. Thanks for the tip! Pics would be great when you get to it. Mine had a bunch of Compaq servers when I hauled it off but its not a Q rack. Then it had the Harris RF-301 but that station has gone to a friend who has time to work on it.

The plate and filter iron has to go in the bottom then one of those variacs above it. The only reason for the variac is to adjust plate voltage. I have a 60A motor driven stabiline unit that could be used for mains regulation in that rack but it is 120V, not 240. Well I have two, so I could use two, but that would be very odd to regulate each side of the 240V separately wouldn't it?

At work I sometimes use a Peschel 150 KVA "variac", 0 - 480 VAC out @ 180 Amps.  It is housed in a large cabinet with 3 large rectangular cores with chain drive.

There is something like that but not so powerful as yours, at 'The Black Hole" surplus. Its a big floor mounted thing and the pieces move vertically via sprockets and 'bike chains'. It was offered at a good price but I'm not sure I needed a whole house variac.