[Hammarlund] Comet Pro Question

[Joe Connor]

As you know, I am currently working on a Comet Pro that I bought recently. I'm in the process of replacing the caps. The set plays very well and has impressive sensitivity for its age.

I ran across a mod, however, whose purpose I don't understand. A switch was added to the front panel to switch between headphone output and loudspeaker output. When the switch is in loudspeaker position, the output xformer is switched out of the circuit and B+ goes directly to the speaker terminals. When the switch is in the headphone position, the output transformer is switched into the headphone circuit. Judging from the wiring and the switch, this work was done in the late '30s or early '40s.

Is there a reason why this would be done? Neither the primary nor the secondary of the output xformer appears to be open. Is there any advantage to taking the output xformer out of the circuit when using a loudspeaker? 


What's also interesting is that over its 80-year life, this set had only one repair: a replaced bypass cap. Judging from the style of this cap, this repair, too, was done in the late '30s or early '40s.


As always, thanks for your help.


                                      Joe Connor