A 1930 Screen Grid Regen

Introduction

The late 20's included two important developments in amateur receiver design. One was the AC operated receiver and the other was the screen grid detector. Both of these offered significant advances over the triode regenerative detector plus one stage of audio receiver that had been a ham shack standard. Georage Grammer, Assistant QST Technical Editor, described a two tube AC receiver in the December 1930 issue of QST. I've built a similar receiver.

**** In this page I've borrowed heavily from his article in order to retain some of the "flavor" of the times. ***

Experiments in the QST labaratory with screen grid detector convinced them that, for CW reception at least, a two tube receiver would give all of the sensativity and volume that the average amateur required. Aside from the greater sensativity of the type 24 tube as a detector and the consequent desireability of using it with any type of receiver, there is also a great deal of satisfaction in being able to plug into a light socket to get power to run the set - and know that there is no battery to be charged after several hours of continous operation.

I must confess, however, that there is one thing lacking in this receiver. When planning the set a means of controlling volume was not given a thought, since it was not expected that two tubes would give more than comfortable signal strength. It should have been incorporated, however, because the set really needs one. The "sock" of many ham signals is too great for real comfort, especially with a good receiving antenna.

Constuction

The circuit is the "old standby" regenerative detector and one stage audio, capacitively coupled to the antenna and with such modifications as are necessary or desirable for AC tubes. A diagram is shown below and the various photographs show the arrangement of the apparatus.

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Adjustment and Operation

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