[mikethedruid]

Some of you may remember that several years ago I bought a Scott SLRM "morale" receiver. It has sat since then, and I have not gotten around to working on it. The fact is, I have not even opened it up to look at it, let alone testing it at all. I have decided that it is going to be my next radio to tackle. I have done a lot of reading of the articles on ARF about these receivers, and the fact that one should use an isolation transformer with them comes up consistently. I looked at the schematic, and was reminded of my old Navy days back during the Vietnam War, and the educational movie they showed us "115 Volts AC, Your Deadly Shipmate." 

[Video: https://www.youtube.com/watch?v=E-iN21u6nG8]

I remembered that for safety, neither side of a 115V supply on a ship is connected to ground, to the ship itself, which means that while one can get a severe capacitance shock if you come in contact with one side of 115VAC, it is not a direct completed circuit. In the U.S. power distribution system, one side of the 115VAC circuit IS connected to ground. With the circuit of this radio, that CAN cause problems.

[Image: https://64.media.tumblr.com/0a29c49e1b2c...c92499.jpg]

So, I have ordered a 100 watt, 120V - 120V isolation transformer to use with this receiver. I will see if I can find room for it inside the radio. If not, I will have to make a separate box for it. Stay tuned. Over the next weeks this thread may grow as I tackle this receiver.

[rfeenstra]

The SLRM I purchase from Ron and rebuilt has a 3 prong, polarized plug, so no problem. It has been a while, but I seem to remember testing this radio for high voltage on the chassis with various plug connections, and could find none. None the less, it pays to be cautious! Great radio!!!

[mikethedruid]

Well, here goes nothin' ! I lugged the Scott onto my work bench. I had forgotten how HEAVY it is ! Boat anchor ain't in it! This thing, in its case outweighs my Hammarlunds, let alone my National ! It came in a very nice, and heavy, steel case which holds the rack mount radio itself. Here are the first pictures of the set on my bench, first, as received, still in its case, then removed from the case....

[Image: https://64.media.tumblr.com/ffb53a0b1f8b...52327a.jpg]

[Image: https://64.media.tumblr.com/2dfaf825bb09...5c83bd.jpg]

[Image: https://64.media.tumblr.com/bafe77d24688...879354.jpg]

[Image: https://64.media.tumblr.com/3be95dc1611e...b38f94.jpg]

[Image: https://64.media.tumblr.com/c47b5b27317e...5a193e.jpg]

[rfeenstra]

Looks familiar! Well built, aren't they? When you get under the chassis, you'll find all of the part numbers silk screened on the chassis.

[rfeenstra]

It looks like the dial glass has been replaced.  Originally the band numbers were on there.

   


I may be able to help out with that.  A gentleman in England made one for me and he probably still has the files for making another.

[mikethedruid]

Actually, the dial glass in MISSING. I believe it was YOU who was kind enough to send me a replacement, already engraved, back when I first got the receiver and posted about it. I will definitely install it as the repairs go along. Since you have been there, done that, what do you advise I do before actually TESTING the receiver? The usual? Replace all the electrolytics, or the electrolytics AND the paper condensers, or just give her a try? As I read in your old thread, yours was OK from the get go., although you replaced the electrolytics.

[Paul Philco322]

That thing is awesome.

Paul

[mikethedruid]

Well, tonight I tackled the most obvious, I replaced the dial glass. To do this I had to remove the entire front plate. This sounds worse than it actually was. Of course there were all the knobs to remove. These are SERIOUS knobs, the kind with TWO set screws each ! Then there are eight screws with nuts and lock washers on their back, two of which have nuts and lock washers which are virtually impossible to reach, and one screw which goes into a standoff, easy peasey. One does not have to unfasten any of the switches or jacks on the front panel. There is enough loose wire going to them so this is not needed. The lens bezel is held in by four screws, two of which also hold guides for the tuning dial. These needed a little P B Blaster to loosen, but then came off readily. Replacing the dial glass itself was pretty straightforward. I did have to drill four holes in the plastic dial glass to go over little studs in the back of the bezel, and sand the edges of the plastic dial glass a little to fit everything. I also found a few remnants of the old dial glass inside the bezel, a couple of little pieces caught behind the studs, and a larger piece held in place by the dial pointer, which is held to the bezel back by a screw and lock washer. I removed the dial pointer, and sanded and re-painted it white. The piece of old plastic dial glass was very yellow and warped up. It is obvious that it would have needed to be replaced had it still existed. When the pointer had dried, I put the custom fitted dial glass back into the bezel, and clamped it in place using the pointer in the original manner. After that re-assembly of the front went pretty easily, except I left out the two screws and nuts and lock washers which are such a bear. I will have to make a custom tool to put them back. So, here's what the dial looks like now. I have my desk magnifier light shining through from the back to let you see what it will look like illuminated.

[Image: https://64.media.tumblr.com/5c7b6787228b...21d65a.jpg]

[rfeenstra]

I knew I sent one to someone! Happy it worked.

The only caps I replaced in mine were the lytics, as you read. Most of the others subject to high voltage are oil filled bathtubs. I tested those as best i could and couldn't find a problem so I decided to run with the old caps in it until a failure happened. So far, so good. Touched up the alignment and it works great. I don't remember how the resistors measured out, but they must have been ok as I don't think I replaced any. I don't play it much any more as I usually listen to my Scott Philly, Scott 16A, or if it's talk radio, my Philco 14. I'm thinking of putting my SLRM in my workshop where I do refinishing work. The problem with that is it would get covered with lacquer dust!

For the dial lighting, you'll find that the original light is totally inadequate. That lamp is in the negative voltage line, and is very dim. It must be in the circuit or the radio won't work. I added an LED backlight system. Works great and makes the dial look good.

[rfeenstra]

For grins and giggles, I fired it up again with a my long wire hooked up. I forgot how sensitive it can be! In the "CW" position you can control the gain of the RF section of the receiver. The sensitivity can be outstanding. But there is a lot of extra atmospheric noise when you get the gain too high. In the HF position, treble response is very good. These receivers were designed to tie into an audio distribution system in a ship. Someday I'll tie it into a HiFi system to see what it really can sound like. Fun radio!

[mikethedruid]

If you put it in your refinishing shop, just make it a little booth of its own to isolate it from the atmosphere. Use a matching transformer, and run a remote speaker in your main room. Problem solved.

[mikethedruid]

Tonight I took the bottom plate off the chassis. WOW ! I have never seen such a beautifully, and durably built radio since my Navy days. This radio was SERIOUSLY constructed to weather the elements at sea. I have decided to take rfeenstra's lead and start by just replacing the electrolytics. I will probably measure them and take good pictures of them, and see if Hayseed Hamfest can make me some replicas to use. All the paper condensers one would normally have to replace are hermetically sealed away from the elements in little metal cans, so they may well be fine for years and years. Here are pictures of the underside of the chassis before I start any work. First is an overall view, then a series of shots going from the electrolytics down that side of the chassis, then up the other side to the front, and finally the middle of the front.

[Image: https://64.media.tumblr.com/f7c92356b8fc...e56746.jpg]

[Image: https://64.media.tumblr.com/367abd0f43eb...c98405.jpg]

[Image: https://64.media.tumblr.com/af9a6c49298a...900023.jpg]

[Image: https://64.media.tumblr.com/efc925d590fe...b25b72.jpg]

[Image: https://64.media.tumblr.com/8d1d32a77b2d...ee46cd.jpg]

[Image: https://64.media.tumblr.com/a53cbade7d3f...ca0da9.jpg]

[Image: https://64.media.tumblr.com/a178b09573fe...04d123.jpg]

[mikethedruid]

OK, now I need HELP ! Rfeenstra, or anybody who knows, what is the proper connector to use for the antenna? Is there a part number? The one on my set appears original. It is a green, cad plated socket with a round prong in the middle.

[rfeenstra]

Originally. I think they used a heavy coax to to a wire antenna somewhere on the ship or out side the building. I just use a clip lead on the center prong of the connector connected to my long wire. I don't have the proper connector. I knew you would be impressed once you got to the inside!

[mikethedruid]

I didn't do much with the Scott today. I just tested the 1629 magic eye tube. Fortunately my Simpson lists it in the appendix part of the lists, and tests it completely. Nice bright eye! tests good, which is fortunate. I have bought another just to have on hand. All the other tubes I already have. Lately I have been testing tubes I collected over the years.... HUNDREDS of them. Most of them are good. Maybe 10% are bad, or have no legible type markings. I've had to buy a LOT of boxes for them. LOL! but they are all boxed and labelled. I just pray that when I'm gone my foster son finds them a good home, or sells them to someone who will want them. They are worth a LOT of money, even if you just figure the average value at $5 apiece.