Scott SLR Navy model number question

[Dennis Kunkle]

I have an SLR-12-B that I'd like to restore. (I've already restored an Export) What does the letter B signify? The schematic at NA is for an A.

[Mal Fuller]

Hi Dennis,
We have an SLR-12B (nice set). We have a comprehensive 54 page manual with photos (+schematics) for our set that we got from W7FG Vintage Manuals. I just checked his website and it is still up & running. It is:
http://www.w7fg.com

[Dennis Kunkle]

Thanks Mal.......I will.....DENNIS

[Mal Fuller]

Hi Dennis,

I first left this last night, and I guess it wound up in cyberspace. Here is an Antique Electronic Supply description of a Hammond transformer that will match your SLR-12B to an 8 ohm speaker. It works very well for us.
P-T119DA

Catalog Page 37

Transformer - Audio Interstage, Hammond, 12 Watt
Developed in response to requests from the "Collins Collectors Association" , this is a matching audio transformer for older equipment with 600 ohm audio output, driving modern speakers.

Or for "classic" high impedance speakers used with newer equipment, simply swap primary for secondary (ie...4 or 8 ohm input and 600 ohms out).

Key Features Isolation unit: (i.e. seperate primary and secondary)
Primary: 600 Ohm (with 6" wire leads)
Secondary: 8 Ohm with 4 Ohm center tap (with solder lugs)
Power: Rated at 12 watts
Frequency Response: 30 Hz - 20 kHz
Weight: 1.3 lbs.
Mounting: 2 hole u-bracket mount - on 2-3/16" mounting centers.

RoHS Compliant

[Dennis Kunkle]

Thanks for the info....I don't think running a 500 ohm speaker off of the 600 ohm terminals is a major problem for the time being, but correct me if I'm wrong. I received the manual and I'd be lost w/o it! At any rate, I've replaced the major electrolytics and I've now moved on to other replacements.  The resistors ALL need replaced; they're not just a little high, but wildly high! This is a new one for me. I measure each one in the circuit, then I find it on the schematic to verify.  Then I check it after I've removed it and everytime there is no mistake!  They're incredibly high in value: 100 to 200%. Seems odd to me. But I'm pushing on LOL. For those bathtub caps, I have no way to test them so they're getting replaced. However, I am not doing restuffs; I'd be at it until next year at this time! Plus, many of them would require ridiculous dismantling of the chassis to get at them! If I can remove them, I just stick in a terminal strip.  If removal is out of the question, I just get creative!  The audio has come a long way at this point. All of the controls work but there is a distortion that I hope to get at. I suspect that it a cap somewhere as opposed to a resistor, but since all of the resistors are bad, who knows? The fact that it is working is encouraging, but I've got a long way to go. Are there caps that would be suspect? (for distortion)

[Mal Fuller]

Good to hear your update, Dennis.  I would change C-146, C-147 & C-148 which are all audio coupling capacitors rated at .05mfd @ 600wv.  One or more of these three is the likely source of your audio distortion.

On average, those oil filled "bathtub" capacitors are pretty immune to moisture and other wax capacitor perils, hence I'm not sure I'd ever shotgun the whole set.  Our SLR-12B has 100% original capacitors and has performed many years reliably with the originals and still does so.

I'm glad glad you have received your manual.  They do a nice job putting it together, don't they?

I posted regarding the Hammond audio output/matching transformer simply because I thought you'd appreciate knowing one simple way to connect a variety of more commonplace speakers to your set.  If you're happy with the audio capabilities of your 500 ohm speaker, that's certainly okay by me!  

Using the transformer I mentioned, we have our SLR-12 connected to a Hammond organ remote speaker that we acquired separately.  It's cabinet is handsome looking and it provides us with a very pleasing sound befitting a Scott radio receiver.

[Dennis Kunkle]

Thanks for your interest! As it turns out, 2 of the 3 caps that I replaced are among the three that you suggested. C-147 is an oil filled type and I didn't do it. While there are still many resistors left to replace (these are only 50 to 100% high LOL), I believe that I corrected the distortion. The grid filter resistors on the IF amps were the culprit. One was open and one was super high. Right now, the set seems good! The speaker needs only 10% volume to sound normal.  It gets too loud at only 30%. Is that due to the incorrect ohms?

[Mal Fuller]

I doubt the excessive volume is related to your speaker choice, but I've zero experience with speakers in the area of 600 ohms.

Dennis Kunkle said:

Thanks for your interest! As it turns out, 2 of the 3 caps that I replaced are among the three that you suggested. C-147 is an oil filled type and I didn't do it. While there are still many resistors left to replace (these are only 50 to 100% high LOL), I believe that I corrected the distortion. The grid filter resistors on the IF amps were the culprit. One was open and one was super high. Right now, the set seems good! The speaker needs only 10% volume to sound normal.  It gets too loud at only 30%. Is that due to the incorrect ohms?

[Norman S Braithwaite]

I wouldn't worry about too much gain.  It may be helpful for weak stations.  Remember, at the time these receivers were in daily use nearly all stations of interest were feeble when on a ship in the mid to north Pacific and farther west.

 

Norman

Dennis Kunkle said:

Thanks for your interest! As it turns out, 2 of the 3 caps that I replaced are among the three that you suggested. C-147 is an oil filled type and I didn't do it. While there are still many resistors left to replace (these are only 50 to 100% high LOL), I believe that I corrected the distortion. The grid filter resistors on the IF amps were the culprit. One was open and one was super high. Right now, the set seems good! The speaker needs only 10% volume to sound normal.  It gets too loud at only 30%. Is that due to the incorrect ohms?

[Dennis Kunkle]

New questions! The radio is working great! I replaced every resistor, with the exception of several that poke out of the chassis from the IF cans. Now with this set working great, I should let a sleeping dog lie, but with a typical resistor in this set being 200%+ high in value, I'd like to check them. (1) Studying the can, I see two nuts underneath that I assume hold the transformer's can. Does the can/shell then simply lift safely off?  (2) The "first" 2 tubes are listed as metal tubes and the rest as glass. Some of the glass ones are presently metal, which I understand is not a problem. The oscillator (6J5, I believe) is one of the 2 metals and it is currently a glass type. Since the radio works fine, is this also not a problem?

[Mal Fuller]

The lack of a shield on the glass 6J5GT ruins the Super Low Radiation characteristics of your Scott SLR-12B.  You are in imminent danger of a Nazi submarine zeroing in on your receiver!

Dennis Kunkle said:

New questions! The radio is working great! I replaced every resistor, with the exception of several that poke out of the chassis from the IF cans. Now with this set working great, I should let a sleeping dog lie, but with a typical resistor in this set being 200%+ high in value, I'd like to check them. (1) Studying the can, I see two nuts underneath that I assume hold the transformer's can. Does the can/shell then simply lift safely off?  (2) The "first" 2 tubes are listed as metal tubes and the rest as glass. Some of the glass ones are presently metal, which I understand is not a problem. The oscillator (6J5, I believe) is one of the 2 metals and it is currently a glass type. Since the radio works fine, is this also not a problem?

[Dennis Kunkle]

Just how exactly is this transformer hooked up/installed?

Mal Fuller said:

Hi Dennis,

I first left this last night, and I guess it wound up in cyberspace. Here is an Antique Electronic Supply description of a Hammond transformer that will match your SLR-12B to an 8 ohm speaker. It works very well for us.
P-T119DA

Catalog Page 37

Transformer - Audio Interstage, Hammond, 12 Watt
Developed in response to requests from the "Collins Collectors Association" , this is a matching audio transformer for older equipment with 600 ohm audio output, driving modern speakers.

Or for "classic" high impedance speakers used with newer equipment, simply swap primary for secondary (ie...4 or 8 ohm input and 600 ohms out).

Key Features Isolation unit: (i.e. seperate primary and secondary)
Primary: 600 Ohm (with 6" wire leads)
Secondary: 8 Ohm with 4 Ohm center tap (with solder lugs)
Power: Rated at 12 watts
Frequency Response: 30 Hz - 20 kHz
Weight: 1.3 lbs.
Mounting: 2 hole u-bracket mount - on 2-3/16" mounting centers.

RoHS Compliant

[Mal Fuller]

The Hammond transformer's primary is attached to the 600 ohm output.  The transformer's secondary hooks to your 4 or 8 ohm speaker and has taps available for either impedance.  You may mount the transformer where it best suits you.  Mine is in the Hammond Organ remote speaker cabinet, but it may instead be located on the radio's chassis or on the speaker.  

Keep an eye out for enemy subs.