Author Topic: 311A Equalizer Applications?  (Read 857 times)

Offline WEBellSystemChristian

  • **
  • Posts: 3463
  • Grandpa's 1955 Western Electric 500
311A Equalizer Applications?
« on: October 07, 2015, 07:46:05 PM »
Does anyone know if the 311A Equalizer (used on 500 series sets from '48-'51) had another common application by Bell System? I was just curious, because if I ever came across a '50 500 with the equalizer removed, I could potentially remove the equalizer out of said equipment and install it in the 500.

I know there was a 500 model designed for long-loop circuits (forgot model number) that had a 311A installed, but those are just about as rare as a '50 anyway!

Christian Petterson

"Whether you think you can or think you can't, you're right" -Henry Ford

unbeldi

  • Guest
Re: 311A Equalizer Applications?
« Reply #1 on: October 07, 2015, 08:08:39 PM »


The 311A was used on the 500A and B, and the 501A and B with the 425A network, but also on the 500J, K, and T.

The J,K,T also came without the 311A equalizer, later, but could not be used closer than Zone 3 from the CO.

I can't see why the 311A would be used anywhere else, because the thermoelectric elements were specifically tuned for the characteristics of the 425A network and the accompanying T1 and U1 elements.




Offline G-Man

  • **
  • Posts: 1957
Re: 311A Equalizer Applications?
« Reply #2 on: October 07, 2015, 10:30:17 PM »
snip...
I know there was a 500 model designed for long-loop circuits (forgot model number) that had a 311A installed, but those are just about as rare as a '50 anyway!

You may be thinking of 507A/B or 509A/B* sets that were equipped with the 151C/F amplifier, and were intended for use on long-loops.
 
*Wallset versions were 557A/B and 559A/B

 
« Last Edit: October 07, 2015, 10:52:52 PM by G-Man »

Offline paul-f

  • **
  • Posts: 3215
    • Old Telephones as Entertainment!
Re: 311A Equalizer Applications?
« Reply #3 on: October 07, 2015, 11:40:27 PM »


The 311A was used on the 500A and B, and the 501A and B with the 425A network, but also on the 500J, K, and T.

The J,K,T also came without the 311A equalizer, later, but could not be used closer than Zone 3 from the CO.

I can't see why the 311A would be used anywhere else, because the thermoelectric elements were specifically tuned for the characteristics of the 425A network and the accompanying T1 and U1 elements.

I believe the point of the 500T, which was later remarked J/K for the 500J and K, was that it did not have the equalizer, but a small terminal strip.
 
At the time 500Ts were made, sets with the equalizer were marked simply 500, which was remarked A/B for the 500A and B sets at the same time as the J/K markings were introduced.
 
Visit: paul-f.com         WE 500  Design_Line

.