News:

"The phone is a remarkably complex, simple device,
and very rarely ever needs repairs, once you fix them." - Dan/Panther

Main Menu

Now the Story Can be Told - 1949 WECo 500 Set

Started by Dan/Panther, March 20, 2010, 11:08:11 PM

Previous topic - Next topic

Dan/Panther

I have a sneaky suspicion that people are misinterpreting what the intended meaning was of  the press release dated April 1951....

Several sources confirm the report
in the April 1951 Bell System Technical
Journal, that the 1948 field trial with
50 pre-production sets used by 300 persons
was followed by a larger trial using
"the first four thousand production
sets in November 1949.

It doesn't say that the first 4000 were dated 1949, it says they would be distributed in November of 1949 as a Larger TRIAL....after the initial trial of 50 Pre-production sets (Like mine)
I think it is possible that the first 4000 sets manufactured, and INTENDED for release in 1950, along with the additional 82,000 sets dated 1950. Just because they were made in 1949, does not mean they were dated 1949, just like car manufacturers, they release the new model in September, but are dated the next calender year.
I think the 4000 sets referred to were the first 4000, of the 86,000, to be distributed in late 1950 as 1950 sets. They started production in the latter part of 1949, with 1950 dates, the first 4000 were distributed as a trial.

JMHO;
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Jim Stettler

I think that the production dates you find on phones are when the were produced.
My  1965 mustang was a birthday car from September 13 1964. It was a '65 vs 64-1/2. This was because model years in 1965 started in Septyember.


I concour that the November '49 sets may of been part of the 1950 run.  This is because there are earlier dated 1949 components that have been shown. These earlier dated components are probably from early-production sets.
JMO,
Jim
You live, You learn,
You die, you forget it all.

bwanna

ok, jim.....you have dashed my hopes, but i get it now.

it did not occur to me that the 50 pre production sets would be brought back to the lab, modified, then sent out again.

of course, the term "early production" itself indicates these models would be all the same. production....production line.....duh.

i must have missed this somewhere, but who has the phone pictured on paul f's site with the "birthday dated" dial. ???
donna

Dan/Panther

Jim;
The only 49 dated component I'm aware of is Paul's Dial, what else exists ?
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Jim Stettler

Quote from: bwanna on May 09, 2010, 07:15:59 PM
ok, jim.....you have dashed my hopes, but i get it now.

it did not occur to me that the 50 pre production sets would be brought back to the lab, modified, then sent out again.

of course, the term "early production" itself indicates these models would be all the same. production....production line.....duh.

i must have missed this somewhere, but who has the phone pictured on paul f's site with the "birthday dated" dial. ???

Donna,
My theory is based on 50 sets being used among 300 users.  If aiming dots were absent on the first trials and added later. This is my best guess.
I still lean toward the dial trials being seperate than the field trials.
I think the TT document I refered to is in the TCI library.
Jim
You live, You learn,
You die, you forget it all.

Jim Stettler

Quote from: Dan/Panther on May 09, 2010, 07:21:11 PM
Jim;
The only 49 dated component I'm aware of is Paul's Dial, what else exists ?
D/P
I was thinking there were other components on the list that Paul posted regarding early 500 sets. It was around the posting of "Paul's Points to Ponder". If I wasn't so busy i would spend to much time opiniating on the points that have been coming up. As it is I am checking the forum and making slight comments.

Typicalliy I am mostly offline this time of year. If it wasn't for the "charm" of the forum, I would be.
JMO,
Jim
You live, You learn,
You die, you forget it all.

zuperdee

Wow, this thread is still going!!!! I am taking notes here--some of what has been revealed in this thread is making it into my history of the 500, too! Please folks, let me know if I have gotten anything wrong. I am trying very hard to fill in some of the blanks in my history now.

See here:

http://members.dslextreme.com/users/zuperdee/telephones/500_history/we_500_history.html

-Daniel

Dan/Panther

#907
The only chink in my armor about the first 4000 being dated 1950, was the fact that Paul has a dial dated 1949. I could not explain that until it dawned on me....
They had separate dial trials, it is possible that these dials were dated 10-49, as that would fit with a 11-49 test run, and Paul has been fortunate enough, to have found one of them. The scarcity of my chassis, and Paul's dial, would fit well into then fact, that no others are still around because, as in my case, the chassis were most likely torn down, and in the case of the dials, they were never used after the tests, because they were no longer new, and torn down for examination.
I think this scenarios goes along ways to explain why I feel, no 1949-500's were ever produced. I think the harder one examines the writings of those that were there, and press releases etc. you can see,  wording was subtle, and is very critical in determining what message was intended in the writings. Back then no interpretation was necessary, as everyone fully understood what was meant by each statement. When someone talked about dial testing, everyone knew where they came from, when someone said initial sets, everyone knew what sets were being spoken of. This 61 years later we are trying to put together a picture puzzle with 1/2 the piece missing.
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Dan/Panther

We've had quite a few discussions lately about the need or not of the Equalizer. I started to do some reading and read that the varistor does in the handset, exactly what the Equalizer did. Is this why the Eq was eliminated ? It appears that the description of the function of a varistor as in the U1 receiver is almost exactly what the Equalizers definition is.
Here is what a varistor is said to accomplish......

When a small or moderate voltage is applied across the electrodes, only a tiny current flows, caused by reverse leakage through the diode junctions. When a large voltage is applied, the diode junction breaks down due to a combination of thermionic emission and electron tunneling, and a large current flows.

So the varistor in the Handset appears to do exactly what the varistor in the EQ did.

Did the G1 Handset always have the Varistor in it, or was it added at about the same time the EQ was eliminated ?

D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Phonesrfun

The varistor in the handset was there from the git-go, and it did not replace the equalizer.

The puropose for the varistor in the handset across the receiver was to shunt loud clicks from hurting the ear.  It was described in the 1949 Bell system announcement, and was in the circuit design as I understand it from the very beginning.

The varistor in the equalizer was only there to protect the filament in the thermistor tube from high voltages.  When a phone is ringing and has 70 volts AC on the line, when you answer the phone, it takes a split second for the relays in the central office to detect the phone being answered.  Therefore, when answering the phone while ringing current is being applied, there would be a split second of high enough voltage to burn out the equalizer filament in the thermistor tube if there was no varistor across it.

So, the purpose of the varistor across the receiver was for a totally different purpose than the varistor in the equalizer.
-Bill G

Dan/Panther

#910
Quote from: Phonesrfun on May 10, 2010, 02:45:29 PM

The purpose for the varistor in the handset across the receiver was to shunt loud clicks from hurting the ear.  It was described in the 1949 Bell system announcement, and was in the circuit design as I understand it from the very beginning.

Bill;
Bear with me on this. The highlighted text above was exactly what I read was the reason for the Equalizer.
"If it wasn't there the sound at the receiver would be so loud as to be uncomfortable for the listener."
Not an exact quote but the jest of the comment is the same.

So if the clicks were so loud to bother the listener, is it too much of a leap, to imagine that the loud short loop reception, could be dampened for the same reason at the varistor in the handset, not by design, but by accident ? It has been said that; "the equalizer was incorporated for the dampening of the loudness of the short loop, ( I may have that part reversed ?) but what would happen if that same phone, without the equalizer, was utilized in a short loop area  ( OR  Whichever it was that was the problem )  then what, the end user would just have to put up with ?   What magic all of a sudden made that problem go away, or was it theory that never even existed ? Something is just not making logical sense here.
Putting aside the Varistors INTENDED use, couldn't it also of had a beneficial side effect, not by design, by accident ?

Scroll up to 500 C-D....
http://www.paul-f.com/we500typ.htm#Key

Where these varistors located inside the network ?

D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Phonesrfun

Clicks in the receiver are caused by transient voltage spikes that are in the order of a volt or two at their peak.  The actual A.C. voice voltages in a receiver are measured in milivolts, so a transient that is in the magnitude of entire volts is pretty loud and needs clamping.  that is the purpose of the varistor that is across the receiver.  The varistor in the receiver does not have the sensitivity, nor is it in the proper place in the circuit to accomplish a variable volume control.

Remember that the telephone circuit has a primary side that in essence is the switch, the dial pulse contacts, the transmitter, and the primary side of the induction coil.  That is the DC path.  The equalizer filament was placed in series with this DC path so that it could sense the loop current that flows through the primary side of the induction coil.  This is the only place that the loop current can be sensed.

The secondary side of the induction coil is in its simplest form, the secondary and tertiary windings of the induction coil and the receiver element.  No direct current flows through the receiver.  Only voice frequency AC and the transient voltage spikes that do make it through the receiver circuit.  Since there is no DC in the receiver side, there is no capability for any component on that side of the induction coil to sense loop current.  All that varistor can do is clamp transient voltage spikes.

When the 425B network came out, they replaced the thermistor tube with another varistor that IS in the primary side of the circuit that had better current sensing and limiting characteristics than the thermistor tube.  The varistor on the receiver was still needed to supress clicks.

When you say "what magic all of a sudden made that problem go away?"  I don't understand what you mean, so bear with me too.

Do you mean when they built the 425B network, the equalizer was not used any more?  that is because a new generation of a varistor was created in the 1952-1953 area that made it so that a varistor could be used in the primary circuit and be done much cheaper than the equalizer.  The Bell system Technical Journal of 1953 announcing the 425B network specifically says that the 425B network was a breakthrough in designing new varistors that could now be used in the primary side of the circuit and replace the costly equalizer.  The way they described it was that there was a breakthrough in technology that had not existed in the 1948-1949 era when the 500 was first designed.  Jim Stettler had a link to that article a while back.  It is kind of technical, and I admit there is a lot of the math and so forth that I don't comprehend either, but if you read just the words you will see how excited they were over the new technology.
-Bill G

Dan/Panther

#912
Bill;
Thanks for explaining all of this. Most of us have never heard this explained before.
The question about the magic, was I haven't heard an explanation of the equalizer was incorporated into the new network. We will never know if we don't ask.
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Phonesrfun

Quote from: Dan/Panther on May 10, 2010, 05:37:21 PM
Bill;
Thanks for explaining all of this. Most of us have never heard this explained before.
The question about the magic, was I haven't heard an explanation of the equalizer was incorporated into the new network. We will never know if we don't ask.
D/P

I think it is good that questions get asked, because unless we do, then we don't learn, and nobody else does either.  Sometimes I am challenged at giving understandable answers, and then I am also learning a great deal too.

-Bill G

rp2813

I think the statements about the first production 500's (for the subscribership at large) having dates no earlier than 1950 is likely correct.

Now that Paul F. has posted pictures on his site of other 1949 components besides the dial, I suspect that there were never any 500 bases dated 1949, but rather there were probably 500's with bases dated 1950 that contained one or more 1949 components.

It was mentioned somewhere in the previous couple of pages that announcements were made that alluded to a late 1949 launch.  My experience in project management with Pacific Bell/SBC/AT&T included a number of efforts that were met with significant delays.  I see no reason to think that this would not have happened with the 500, considering the huge magnitude of the project and all of the tweaks that were found necessary as the result of trialing and testing.  We used the term "Red Jeopardy" to describe the status of a project that was going to miss its target launch date due to unforeseen and/or unpreventable circumstances.  I'm guessing the 500 project was loaded with "Red Jeopardy" situations that pushed things into 1950.
Ralph