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1957 Stromberg Carlson Hands Free Phone

Started by ....., July 24, 2017, 08:25:44 PM

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Alex G. Bell

Quote from: unbeldi on July 29, 2017, 12:33:40 PM
The circuit diagram indicates that the 1583 uses a piezoelectric microphone, so its resistance should indeed be essentially infinite.
Yes, it should be.  Curious that it deflected a compass.

Alex G. Bell

Quote from: unbeldi on July 29, 2017, 12:53:53 PM
The set contains several date markings in forms 7 10, 71x.

I believe at least until the mid-1960s (~1964 last observance), SC used the code format  ww-yy, were ww is the week number of year, and yy is the year.

This clearly deviates from that, I think the year is now simply a single digit, perhaps omitting the decade digit, and the format appears as y-ww.
So perhaps:
710 = March 1967
715 = April 1967
                                 PERHAPS.


The 210558 transmission unit, or network, is the standard type that was used in the 1543.
1967 seems too late for S-C to have been producing a vacuum tube unit.

Alex G. Bell

#32
Quote from: Duffy on July 29, 2017, 11:20:58 AM
Sure, go ahead Paul. If you want larger resolution pictures I have 4000 X 6000 copies of each one.

Doug
I can get rid of the uneven gray background for a library version but might as well do that with the higher resolution version.

Here is what a quick cleaned up version of the current one looks like without getting rid of some residual shading.

unbeldi

Quote from: Alex G. Bell on July 29, 2017, 01:53:20 PM
1967 seems too late for S-C to have been producing a vacuum tube unit.
Well, the components of the 1543 used in this set also indicate a 1950s vintage, the dial is the type of the transition period from the 1400-series to the 1500s.  So perhaps it was a decade earlier, 1957.  We have to review date stamps from the early to mid-1950s.
But, the volume of sales of these sets probably was not high enough to warrant the expense of a complete redesign for semiconductor technology, so I would not be surprised that tube sets would still be sold in the late 60s.

The owner of the set might be able to get other explicit dates from some of the electronic components.

Alex G. Bell

#34
Quote from: unbeldi on July 29, 2017, 02:30:42 PM
Well, the components of the 1543 used in this set also indicate a 1950s vintage, the dial is the type of the transition period from the 1400-series to the 1500s.  So perhaps it was a decade earlier, 1957.  We have to review date stamps from the early to mid-1950s.
But, the volume of sales of these sets probably was not high enough to warrant the expense of a complete redesign for semiconductor technology, so I would not be surprised that tube sets would still be sold in the late 60s.

The owner of the set might be able to get other explicit dates from some of the electronic components.
1957 makes much more sense to me.  1967-68 was around the time S-C began producing 500 sets.  Even though the volume of sales was probably low, I'd think it would be especially low for a vacuum tube product at that point because it would be widely perceived as obsolete.

The 1960 catalog cut is more consistent with it dating back to 1957.  Would be interesting to find earlier and later catalogs to see where it shows up.  Maybe there's something in the Mike Neale part of the TCI library.

Also the dates of the BSTJ articles describing the #3 Speakerphone are relevant since the introduction of voice switching is a much more significant advance over whether tubes or transistors were used as the gain devices.  Two articles are:

v.39 no. 2    Mar '60   265-294    Fundamental Considerations in the Design of a Voice-Switched Speakerphone    Busala, A.

v.40 no. 3    May '61   649-668    Functional Design of a Voice-Switched Speakerphone    Clemency, W.F.; Goodale, W.D. Jr.

ISTR there being a 3rd article.  So by 1960-61 BTL had changed the state of the art and any competing mfr would know this long before 1967 and have had time to respond.

unbeldi

#35
Ok, I should have suggested 1957 right away, had I only cross-checked with my other SC sets of the 1940s and 1950s.

Indeed the format y-ww was used before not after the yy-ww format.

Here is an example of a ringer in a  1443K telephone of 1953:  337
The bottom plate of the telephone set is stamped 338, ditto for the dial.

.....

Quote from: unbeldi on July 29, 2017, 02:30:42 PM
The owner of the set might be able to get other explicit dates from some of the electronic components.

Do these pictures help?

AL_as_needed

Glad I found this thread, very very neat phone. Not normally a huge fan of SC phones, but this is an exception for sure. Thanks for sharing!
TWinbrook7

unbeldi

Quote from: Duffy on July 30, 2017, 08:11:43 AM
Do these pictures help?

Indeed, your pictures confirm the 1957 vintage of your set.  The tubes are clearly marked, e.g., 57-10, and one of those capacitors is marked 620,  probably 20th week of 1956.

.....

Quote from: unbeldi on July 30, 2017, 09:32:56 AM
Indeed, your pictures confirm the 1957 vintage of your set.  The tubes are clearly marked, e.g., 57-10, and one of those capacitors is marked 620,  probably 20th week of 1956.

That phone is the same vintage as myself. 1957 was a good year I guess. :)

unbeldi

#40
Quote from: Duffy on July 30, 2017, 09:44:26 AM
That phone is the same vintage as myself. 1957 was a good year I guess. :)

An interesting question remaining is whether this set still works as well as you do.


Have you plugged it in yet?   Without the microphone, the speaker should work just fine for receiving. The lack of microphone should have no ill effect on the electronics.
I would keep the chassis open while powering up, to observe that the tubes all light up properly.
I would first perform some simple tests on the AC input though.  With an ohmmeter verify that no short exists between the AC line terminals, and from each to the metal chassis.

compubit

Doug -

Quick question about the case restoration: what method did. You use? I have an AE in dove gray and it needs some work on the yellowing, and I'm a little nervous about using peroxide, as I want to keep a uniform color...

Thanks,
Jim
A phone phanatic since I was less than 2 (thanks to Fisher Price); collector since a teenager; now able to afford to play!
Favorite Phone: Western Electric Trimline - it just feels right holding it up to my face!

unbeldi

#42
Quote from: compubit on July 30, 2017, 10:08:07 AM
Doug -

Quick question about the case restoration: what method did. You use? I have an AE in dove gray and it needs some work on the yellowing, and I'm a little nervous about using peroxide, as I want to keep a uniform color...

Thanks,
Jim
Simply use Clorox bleach, diluted 1:3 to 1:2, depending on desired strength. Much cheaper and easier to use.  Safer, because it works a lot more gently and slower.
The color of this 1583 is the same as this Type 1553 wall set, which I bleached just slightly with Clorox.

BTW, I am wondering why the "after" pictures show the set so bright.  I hope it is simply a photographic artifact of intense lighting, not bleaching of the plastic.  It should look a lot darker in reality.  The "before" pictures appear a lot more true to the correct color.

.....

Quote from: unbeldi on July 30, 2017, 09:59:45 AM
An interesting question remaining is whether this set still works as well as you do.


Have you plugged it in yet?   Without the microphone, the speaker should work just fine for receiving. The lack of microphone should have no ill effect on the electronics.
I would keep the chassis open while powering up, to observe that the tubes all light up properly.
I would first perform some simple tests on the AC input though.  With an ohmmeter verify that no short exists between the AC line terminals, and from each to the metal chassis.

I haven't tested it yet. I still need to get another line cord for it, the one that was on it was detoriated beyond use. When I do plug it in, I'll have it plugged into a switched power bar. Just in case of smoke. LOL


Quote from: compubit on July 30, 2017, 10:08:07 AM
Doug -

Quick question about the case restoration: what method did. You use? I have an AE in dove gray and it needs some work on the yellowing, and I'm a little nervous about using peroxide, as I want to keep a uniform color...

Thanks,
Jim

Jim,

All I did was soak it in the garage sink with cheap dish soap and used magic eraser to wipe it down.

Doug

.....

Quote from: unbeldi on July 30, 2017, 10:13:28 AM

BTW, I am wondering why the "after" pictures show the set so bright.  I hope it is simply a photographic artifact of intense lighting, not bleaching of the plastic.  It should look a lot darker in reality.  The "before" pictures appear a lot more true to the correct color.

Before pictures were taken inside the garage under fluorescent lights. After pictures were outside in bright sun light.

The phone had a build up of something on it, it was very dirty. Nicotine build up?????