302 hearing my voice in earpeice

[oldguy]

I have a 1948 WE 302 that was rebuilt in 1959. Everything works but i hear my voice in the receiver when I talk. Any ideas what could cause this?

[TelePlay]

Well, you should hear your voice but the question is how loud are you hearing it. The 302 is an anti-side tone circuit so you should hear yourself talking but at a low volume.

Side tone circuits let you hear your voice and near full strength.

Maybe someone wired the circuit wrong to some how take out the anti-side tone effect or something is wrong with a part in the circuit.

Others can get into more detail of narrowing your problem down to what's wrong. Photos of the wiring, the base, dial and hook switch would be necessary for them to do that.

[poplar1]

Agreed that, unlike a cell phone, you are supposed to hear yourself...this is called "sidetone." However, it should not be too loud on a 302.

Do you hear a pop in the receiver if you push down the hookswitch plunger slowly? If so, may be an open red wire in the handset cord. The red conductor should go from the R terminal in the handset to the R terminal on the induction coil.

[oldguy]

Thanks John & poplar1, this may be normal.

[Dominic_ContempraPhones]

Too much sidetone.  Not normal.

[Dominic_ContempraPhones]

What kind of line are you connecting it to?  On our digital phones, we had to send a command to them to create the desired sidetone -- too little and people yelled.

[oldguy]

Thanks Dominic, it was hooked up to one of my 616s. I think I was being overly critical. It's connected to a POTS line now & seems ok.

[Alex G. Bell]

It's connected to a POTS line now & seems ok.

With induction coil sets (previous to 500 sets) including both 300 series and desk stands or hand telephone sets connected to induction coil subsets, the transmitter output level depends on loop current.  Consequently so does the sidetone if other characteristics of the line (impedance) stays the same.  500 sets provide transmission regulation within the network so transmit and sidetone levels tend to vary less with loop current.

Loop current provided by an on premises PBX OTOH might well be higher than what you receive from your POTS line so that could account for higher sidetone on the PBX, as well as higher transmit level, which you could be unaware of. 

Also, when connected to the PBX sidetone level at the calling phone might change (probably decrease) when a station-station call is made and the called phone answers.  It could go down due to better impedance matching with the answering phone off hook than it was during dialing and before answering.

[Dominic_ContempraPhones]

Gary ... I understand.  What we had to do was achieve full isolation so that we could adjust the level of sidetone on the fly  You may find this interesting ... the default was 12 dB, but we could go as high as 22 or as low as 7, and even none.  But, not for phones in call centers, because they were noisy environments.

We couldn't do this with analog lines.  That was the power of Meridian -- you could change things by typing in a few letters.

SOLR

Sidetone Objective Loudness Rating

The SOLR value is downloaded to Meridian Modular
telephones after sysload except when performing
parallel reload.

Before changing these values, refer to Nortel
Transmission Parameters Reference, NN43001-282.

(1) 12 dB
0 7 dB
2 17 dB
3 22 dB
4 sidetone disabled
The default is 0, indicating no change to the default +45
dB. The number entered in this field corresponds to an
offset value.
The default value is 1 (12 dB). The recommended
North American value for all releases is 1 (12 dB). Does
not apply to M2216.
Note:
The switch will print the actual dB value in overlay
22. However it will only accept a number in the
range 0-4 in overlay 17.