Acceptable break make ratio?

[dsk]

I have just done some measuring, among those 2 but-sets used by the Norwegian Televerket (monopoly)
One has break/make ratio of 60/40
The other 63/37. They are both made by ITT, probably based on a Trimline style handset.

dsk

[Ktownphoneco]

Dag   .....    I hope all is well with you.    The benchmark break / make ratio here in North America is 60/40, with a pulse count of 10.0 pps for private line residential and commercial telephones.    Pulse counts of 8 pps to 11 pps are considered acceptable in a field test with no adjustment required.       Dials used in other applications such as a telephone company test desk, or dials installed in switchboard / private branch exchange (PBX) systems were calibrated to a different standard.     Some applications called for a pulse rates of 11.9 to 12.1 pps, and 17 to 19 pps.   ...  Jeff Lamb 

[dsk]

Thank you. The only reason for complaint here are dialing trouble on my 1946 PAX at on circuit.
We have more or less used the same standards as North America here, at least up to 1970.
Then international standards became more important, but those seems mainly to be based on Bell's experience :-)

dsk

[TelePlay]

Dag   .....    I hope all is well with you.    The benchmark break / make ratio here in North America is 60/40, with a pulse count of 10.0 pps for private line residential and commercial telephones.    Pulse counts of 8 pps to 11 pps are considered acceptable in a field test with no adjustment required.       Dials used in other applications such as a telephone company test desk, or dials installed in switchboard / private branch exchange (PBX) systems were calibrated to a different standard.     Some applications called for a pulse rates of 11.9 to 12.1 pps, and 17 to 19 pps.

Jeff or anyone else,

A lot has been said and known about pulse rate but what is acceptable for the make/break ratio. While 60/40 is the quoted standard, how much variation can there be in that ratio before the dial is said to be out of spec or will not work?

I have a dial that is running at 9/75 pps but the make break ratio is about 68/32 without much difference for each over 9 pulses with about a 1.5% change in ratio from the first to the 9th digit.

1 )  68.32% - 31.68%
2 )  68.63% - 31.37%
3 )  68.32% - 31.68%
4 )  68.63% - 31.37%
5 )  67.65% - 32.35%
6 )  68.63% - 31.37%
7 )  67.96% - 32.04%
8 )  67.62% - 32.38%
9 )  66.98% - 33.02%

Is there an adjustment for this ratio, which for this dial is off by about 8%?

[unbeldi]

Jeff or anyone else,

A lot has been said and known about pulse rate but what is acceptable for the make/break ratio. While 60/40 is the quoted standard, how much variation can there be in that ratio before the dial is said to be out of spec or will not work?

I have a dial that is running at 9/75 pps

What does this designation mean?

but the make break ratio is about 68/32 without much difference for each over 9 pulses with about a 1.5% change in ratio from the first to the 9th digit.

68% is called the break ratio.   68 ms break vs 100 ms cycle.
The make ratio is 32%.

1 )  68.32% - 31.68%
2 )  68.63% - 31.37%
3 )  68.32% - 31.68%
4 )  68.63% - 31.37%
5 )  67.65% - 32.35%
6 )  68.63% - 31.37%
7 )  67.96% - 32.04%
8 )  67.62% - 32.38%
9 )  66.98% - 33.02%

This should be fine, depending on the dial type,  I would not attempt to change it.  What works depends a great deal on the condition and length of the line.

The exact specifications varied from WECo dial generation to generation, it was not always 60%.  What kind of dial is this?

The nominal value by modern FCC specs is 60%,  with a permitted variation between 58% and 65%, according to Reeve, Subscriber Loop Signaling and Transmission Handbook (1992, IEEE).  The central office should accept 55% to 65%.  The difference in specs, I suppose is because of the signal distortion on the line.

Is there an adjustment for this ratio, which for this dial is off by about 8%?

There is no direct tuning as you know, the ratio is given by the physical dimensions of the pulsing pawl vs. location and travel of the springs, but bending the springs certainly effects the ratio, so in that sense one could say they can be tuned.

[Ktownphoneco]

John  .....  This is the Bell System Practices document I follow when repairing and calibrating "Western Electric & Northern Electric" type telephone dials.   There's a lot of useful information included with this BSP, including how Bell technicians field tested the dials from the customer's premises.    Page 5 sets out the acceptable dial speeds for each type of dial in use at the time that this BSP was printed.     

Jeff Lamb

N.B. *  This BSP is provided, with thanks, by the technical library of Telephone Collectors International.   BSP_028-300-701

[TelePlay]

I have a dial that is running at 9/75 pps

What does this designation mean?

Hah, means the "/" key is right next to the "." key and spell check doesn't pick up the intention. My fault for not proof reading.

Meant to type 9.75 PPS.

The dial is a WE 6A dated mid 1956.

And thanks for the replies. Answers the question.