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QUESTIONS AND \j>
WHEN YOU WRITE THE GRID . . .
Don't fail to enclose a stamped, self -addressed envelope with your inquiry if you expect a personal reply.
Don't be impatient if you do not receive an immediate answer. Every letter is answered in the order of its receipt. Do not send a second letter asking about the first.
Look over your files of RADIO BROADCAST before asking a question which might have been covered in a previous issue.
Don't ask for a comparison between manufactured apparatus. The addresses of manufacturers of articles used in the construction of apparatus described in RADIO BROADCAST will be given on request.
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QUERIES ANSWERED
WHAT is THE TROUBLE WITH MY ROBERTS RECEIVER WHEN IT IS POSSIBLE TO RECEIVE WITH THE DETECTOR TUBE REMOVED FROM ITS SOCKET?
C. ]. S— Brooklyn, N. Y.
\VlLL YOU PRINT A SIX-TUBE CIRCUIT FOR USE WITH A LOOP?
G. H. — Chillicothe, Ohio.
I WOULD LIKE A RADIO-FREQUENCY, REFLEX, AUDIO-FREQUENCY, CRYSTAL DETECTOR CIRCUIT EMPLOYING THREE TUBES.
T. L. G. — Philadelphia, Penna.
MAY I HAVE A DIAGRAM FOR A ONE-CONTROL ONI-TUBE REFLEX CIRCUIT?
L. B. — Austin, Texas.
HOW ARE JACKS USED IN RADIO CIRCUITS?
J. P. N. — Savannah, Ga.
I WOULD LIKE A POWER AMPLIFIER CIRCUIT EMPLOYING PUSH-PULL TRANSFORMERS.
E. T. J.— Detroit, Mich.
HOW MAY I PREPARE A CALIBRATION CURVE FOR MY RECEIVER?
C. M. D. — Springfield, Mass. EXPLAIN HOW I MAY MAKE A CHANGE-OVFK
SWITCH FOR TESTING RECEIVERS.
A. C. F.— Freeport, L. 1. N. Y.
A GLANCE at any of the Roberts Knockout circuits will show us that they are composed of two very important units, namely the neutralized radio-frequency amplifier and the regenerative detector. The audio-frequency amplifier addition is either of the audio-transformer or the resistance-coupled type or a combination of both."
Just now we are interested in the two-tube tuner. Not a few questions similar to C. J. S.'s have been received and we endeavor to clear up the situation with the following explanation.
It is quite evident that the radio-frequency amplifier, in this case, is functioning as a detector unit rectifying the incoming signal without the aid of the regenerative detector. In Fig. I is shown a circuit that will aid in putting the entire receiver