Candlestick Receiver Raises an Old E1 Question

[rp2813]

Cruising through the listings on ebay tonight I came across a candlestick with a receiver that has been retrofitted with an HA1 element (see picture). 

This again prompts me to ask whether a retrofit was ever applied to E1 handsets so they could accept an HA1 receiver element.  I understand that retrofitting E1s to replace their truly awful 395B transmitters with F1 capsules was a much higher priority, but am wondering if WECo ever did likewise for the receivers, or did they just leave things alone until they systematically began pulling E1s out of service and replacing them with F1 handsets?

I've never been satisfied with the reception quality on my E1, and I've tried two elements with good diaphragms and found no difference/improvement.  It's fuzzy and fairly squawky compared to an HA1 or U1/3.  Is this a trade-off that must be accepted in order to keep a D1 set looking original, or might WECo have designed a way to retrofit for an HA1?  I've never seen one, but after seeing the candlestick receiver, I'm wondering why not.

[LarryInMichigan]

That receiver was not retrofitted.  The 706A receiver was designed to take an HA1 receiver element.  There are ways to stick a small receiver element into the receiver cup of an E1 handset, but I do not believe that Western Electric ever made such a thing.

Larry

[unbeldi]

That receiver was not retrofitted.  The 706A receiver was designed to take an HA1 receiver element.  There are ways to stick a small receiver element into the receiver cup of an E1 handset, but I do not believe that Western Electric ever made such a thing.

Larry

I can only agree ... and provide some development history:

The response curve of the 557 type handset receiver was very similar to that of the 144 handheld device. But because of the vastly different performance of the 395 barrier-button transmitter over the 323 candlestick transmitter, the overall audio performance was different as well. BTL history states that further improvements, because of better materials, could have been achieved in the 557, but it was not worthwhile because it would also have complicated the design because of increased noise and sidetone.

So, I suspect it was not worthwhile economically to redesign the receiver element on the E1 handset again, because a complete new handset, the F1, could simply be swapped in, which is what we see done on perhaps the majority of 202 type telephones.  The development of the HA1 element was finished just in time for the 302 telephones to be field tested; probably it actually held up earlier testing.

The F1 transmitter, however, was available for production use in 1934 already, so the economic incentive was great to produce a new element mounting immediately. By early 1938, when 302 production had just got underway, the Bell System already had over five million F1 transmitters in circulation, while only about one million F1 handsets had been produced since introduction in 1937.

The response of the HA1 element is much superior indeed, over the 557 type unit, because it eliminated the characteristic mechanical resonances of the diaphragm, which caused distortions.


*AT&T 1975, BTL, A History of Engineering and Science in the Bell System - The Early Years, Chapter 6.4
*BSTJ 1938, Vol 17 (3), p.338, W.C. Jones, Instruments for the New Telephone Sets
*BSTJ 1937, Vol. 16 (3), p.251, E.H. Colpitts, Scientific Research Applied to the Telephone Transmitter and Receiver

[rp2813]

Thanks for the information.  I'm not a candlestick devotee so wasn't aware that the receiver pictured was actually designed to be used with an HA1. 

It does make sense, since a lot of pay phone equipment into the 1950s was still using separate receiver and transmitter, long after most E1 handsets had been pulled from service.

I guess I'll continue to use my E1 handset as the novelty item that it is.  Reception quality depends largely on the type of phone the distant party is using.  Cordless and mobile phones result in the worst, whereas corded phones with high quality transmitter components come through relatively loud and clear.

[unbeldi]

Yes, unfortunately audio quality has not been deemed important anymore in the process of making money in the telecom market place these day.    No more 'Pin drop' quality as it was promoted (Sprint?) right after the Bell breakup.

The lossy compression on most voice-over-IP systems reduces the frequency range of speech even further than was possible with these historic instruments and aggravates the problems with sound distortion.