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311A Equalizer Applications?

Started by WEBellSystemChristian, October 07, 2015, 07:46:05 PM

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WEBellSystemChristian

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



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.




G-Man

#2
Quote from: WEBellSystemChristian on October 07, 2015, 07:46:05 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


paul-f

Quote from: unbeldi 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.

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

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