Finally had a chance to spend some time in the shop this afternoon after a too brief stretch of spring weather, which I spent outside cleaning the yard of winter debris, and playing with the dogs.

As I said earlier, my oscilloscope was not working, so I took it apart (breaking the Tectronics seal) which voids the calibration. I didn’t find anything electrical wrong, but cleaned all the contacts, switches, and rheostats with “Deoxit”. Anyone reading this who is not familiar with Deoxit should become aquainted and purchase a can (aerosol).

Re-assembled everything after a good dusting and air spray, and, IT WORKS.
My friend Pete, KB7OVJ, in Oregon sent me some extra fiberglass alignment tools which arrived in the mail today. So now, I have no excuse for dragging my feet on the alignment process.

(so now back to work)

Today, I found something unexpected, and I was unable to resist. This past week,an early SX28 s/n 177313 (which dates it 1943) was found (covered) in an attic in Steilacoom, Wa. We had to drive to Tacoma (30 miles) to pick it up, but that time spent is well worth it.
It appears complete (all the parts are there), and, is very clean. Removing the rf deck cover, I found the tuning caps shiny bright, looking almost new. As (pic)1 shows the inspection document is still attached, but not dated. The cabinet paint is of a slightly different color than the sx28a but the cabinet has no big chips, rust, dings or dents. Hopefully it will just be cleaning on this one.
With another to look at maybe this will help trace the 2 cut wires?

So, another project is in store after completing the reason for this blog.
Another question has now come up. If this model receiver is becoming so rare, why have 2 of them surfaced for me in the last month? hmmm. something to ponder about!!

Approaching the half way mark of the capacitor replacement. Unfortunately, the 2nd half is going to be the harder. 5 more to replace, then, the “rf” deck has to be removed for access to the remainder. Hoping I am up to the challenge. Patience is a virtue on this project. I could not have done it a few years ago. But, since there is no hurry, and each replacement is progress, we are moving along slowly. When I get frustrated I have learned to lay down the soldering iron and walk away for awhile. A bit of rest and fresh eyes seem to make a big difference.
Today, I discovered 2 wires that have been cut, folded back, and taped with friction tape. (an indication of how long ago this took place). So, there is some circuit testing & wire pulling going to take place. At this time I see no indication where they came from. One is light brown & the other green, so I doubt they have any relationship. We’ll see.
More to come…………

Well, I am a bit less intimidated by this project as each step proceeds. “Stuffing” new caps into old “cans” sounds like hard work, but really it is just time consuming. For aesthetic value, it is worth it.

Most important is to get the wires back correctly onto the terminals. A dab of nail polish works great for color coding. The open end of the cans is just slightly folded over, so carefully straighten it out. Then into a 300 degree oven to soften the glue holding the bakelite & terminals. A tiny screwdriver prys this loose of the can. Then a woodscrew partially driven into the old contents lets you remove its innards with just a tug.
In (pic) 1 you can see the old parts alongside the new much smaller capacitor. (pic) 2 explains all by itself why replacing caps is necessary. Over a period of time caps (especially) electrolytics will dry out. When they are new they are soaked in a boric acid solution. When power is applied if dry, (pic) 2 is the result, OR much worse damage to other components.

Being careful of polarity, install the new caps, seal (glue) the bakelite back onto the can & re-fold the aluminum that was pried open. A small ball-pien hammer works great.The finished product is shown in (pic) 3. As you can see, I had to install a new connector. Then back into the radio—this is where the color coding is appreciated!!

It was suggested to me that I keep a diary with pictures of a project that I began in Mid January 2011. Mostly for my own satisfaction and documentation of the proceedings. If anyone can use the info here, PLEASE DO, just acknowledge the source please.

To those who may be interested. Recently, at a “garage sale”, I found and purchased a 1944/5 Hallicrafters SX28A.  At the time, I did not know that it might be a valuable receiver from the past, just that it was something that I needed to bring home. It was in pretty sad shape (pic) having sat under a bench in a garage for approx. 50yrs. I purchased it at a VERY reasonable price and had help loading it into my vehicle. It weighs approx 78 lbs.

Arriving home and putting it onto my workbench, I looked inside and found the original manual, not in very good shape, but still readable. Copies were made of it and the orig. is now in acid-proof folders. Research  on the  inet  has told me that it is a very rare receiver from WW2 and there is only a very few hundred left (that are known). The serial number (HA9446) dates it late 1944 to Sept. 1945. Many hours have been spent sanding out scratches, dents & dings of the cabinet (pic)  and repainting as close to the orig color as I could. Also lots of time was spent (both mine and Patrice) cleaning the front panel. (pic)

The main tuning dial (gearbox) had previously been removed and was very much out of adjustment. One whole day was spent cleaning the gearbox and lubing the moving parts. It is a mechanical wonder. (Beautiful). (pic) Another day was spent restring the “bandspread” and band indicator mechanism. (pic) It had been tried at some time in the past and was strung very much wrong. The knots on the ends of the band indicator (a “rube Goldberg”) device (pic) have to be in exactly the right place or  it will not work. Thanks to Patrice for her help and patience doing this. New capacitors (58 of them)  were ordered and have now arrived & and  a very tedious process has begun. 

Today I replaced 2  easy ones, and ran into a problem of which I had no knowledge.  Electrolytic caps are polarized and the schematic does not indicate this.  It is now figured out thanks to Phil. I would like to acknowledge Phil at Phil’s old Radios for  his very helpful info on the work accomplished so far. Much info is available on his website. Especially the article describing how to install new electrolytic caps in old “cans”. I will soon try this????? More to come……