812 Rig - Progress (cont)

[KA8WTK]

  Just a couple more pictures at this time......
  The first is the antenna change over relay. What a beast!
  Second is the deck that holds the Navy transmitter before some cleaning and painting.
  Last is the cleaned and painted deck with the CBY unit plugged in. The deck still looks a bit rough due to the pitting from rust. But, I'll take it as the loose rust was sanded off and the paint will stop any further rust.
  Now, on to the modulator deck..............

[KL7OF]

Is that antenna relay the rack and pinion type?.......A motor driven pinion moves the rack back and forth to make and break the connection.  I saw one that came out of a WW2 vintage vhf military rig .   It made a lot of noise when it operated.   very cool...
Nice job on the rig cleanup!..    Steve

[KA8WTK]

Hi Steve,
  The relay is just a big DPDT type with a set of contacts on each end.
  Thanks for for the comments. Most of what I am doing as I go through the decks is cleaning and trying to understand why some things were done the way they were during construction. This also involves changing those things I don't like from a safety or other perspective. For instance, all the HV wiring is typical 600 volt insulated solid house wire. I am changing any wiring that carries over 400 volts to ignition wire. Another thing I don't like is solid wire used when wiring plate caps. I like something flexible.
  I am just getting into the modulator deck and it appears that I will need to "clean-up" some wiring under this deck.

[KL7OF]

Wow!... What is that Mod transformer?  Very capable for an 812 rig..
EDIT.... I see from your other post that it is a 300 watt Stancor...

[KA8WTK]

The mod iron is a Stancor A-3898. The data on the AM Window says it is a 300 watt piece of iron.

[The Slab Bacon]

Bill,
    that is a schweet lookin mod tranny, but it is not a potted unit and it is sitting on a rather rusty chassis. Have you done a hi-pot test on it yet?? If it is not potted, they are somewhat succeptable to absorbing moisture.

You may want to "bake" it before applying any hv to it, just to be on the safe side.
Transfomas like that, I like to remove the end bells and bake them at 190-200 degrees for 8 or 10 hours to expell any trapped moisture that may be in the insulation. then while they are still not, drop them into a bucket of good oil based varnish to cool off. After they have cooled off hang them over the bucket to "drip dry". As they cool and contract they will pull the varnish into the windings and seal them. Allow it to dry for a day or so and them dunk it again and let it dry and redunk. (do not rebake afterwards)

Several dippings and dryings will form a nice varnish "glaze" on it and seal it from future moisture problems. this will do wonders to extend the usable life expectancy of an old transfoma. Give it a few weeks in a warm dry place to dry thoroughly before reinstalling the end bells.

                                                    The Slab Bacon

After several du

[KA8WTK]

Hi Frank,
  Bake it eh? I could probably take it to work and bake it in our convection oven for the day and then put it in a dessicator chamber for a while. The dessicant will remove any residual moisture.
  I may not be "wet" at all. The transmitter has been sitting in the shack for over two years high and dry. The transformer itself is not rusty. And, the shack is dry and dehumidified on a year round basis. (I do it for the cat. He has asthma.) So it is intentionally very dry in here.
  That said, a little heat will probably do it good and be on the safe side.

Bill

[The Slab Bacon]

Bill,
    I have baked and varnished many transfomas so far, and none of them has given me a problem. I have done that with plate, mod, interstage, and small power transfomas. I bake the smaller stuff in a large toaster oven on the back porch so the yl doesnt piss and moan about the smell. the varnish "glaze" really does wonders for small paper covered transfomas that have the paper covers crumbling with age. It hardens the coverings back up and they look like new!!

                                                         the Slab Bacon

[KA8WTK]

Hi Frank,
  I pulled the transformer off the chassis to clean it up and to see about pulling off the end bells when I noticed a little removeable cover on the underneath of each bell. Having looked in there, I don't think I am going to place the xformer in an oven. The transformer is already full of tar! See the photo for the black goo inside the bell end.

Bill

[The Slab Bacon]

Kool Beanz!! Some of those style transfomas were actually potted. the small inspection cover is where they poured the potting material (tar) in. I bet finding that out made you feel much more confident in it, I know that I would be.

                                                         The Slab Bacon