Radio 7AG J C Milne letter

Recognised text

Text below was produced by optical character recognition and may contain errors. Check it against the original.

Ta ftdne       1A

            “RADIO”                                               July 25, 1923.
  turns each, owing to the .0005 M.F.       the process described in ‘‘The Experi-
  condenser being used for tuning the       menters’ Corner’’ of Radio No. 8, pp.
  former, use a H0-turn coil for the pri-   182, under heading of ‘‘Improving
  mary. The ‘‘Phillips E*’ Valve should     Honeyeomb Coils.”” (2) Yes, a slight
  funetion the same as a French ‘‘R.”’      improvement would result. (3) P
  Use three to four volts on the filament   bably you are not using sufficient re-
  and 30 to 40 volts on the plate.          action coupling.
    E. §. (Mincha West) asks: (1)              E. M. (North Melbourne): You
  Number of turns of wire for the fol-      query No. 1 has been referred to Mr.
  lowing wave lengths, using 001 M.F.       J. H. A. Pike, at Epping, N.S.W. Re-
  variable condenser:—(a)     170-375;      garding queries Nos. 2 and 3, we re-
  (b) 200-515; (e) 240-730; (d) 330-        fer you to The Wireless Experiment-
  1030; (e) 450-1460. (2) Is cotton-        ers’ Manual, an. excellent book by
  covered wire better than enamelled        Elmer E. Bucher.
  for above coils?                                  R. (Windsor, Melb.) asks: (1)
    Answer: (1) Assuming a mean di-          Advantage of honeycomb ecoil over
  ameter, of -two 1ncheq wind as follows:    tuning coil and condenser? (2) How
    (a) 2551(11)35; (¢) 45; (d) 60 and to prevent howling using amplifier in
   (e) 75, THese Values are for use in conjunction with crystal set? (3) Can
   the secondary only and the ranges will music be received 65 miles on crystal
   be apprommately that which yon re- set and one valve?             (4) The most
   (uire, but will vary with different suitable aerial?
-+ values‘of “cireuit capacity.   (2) Use      Answer: (1) A honeycomb coil is
   D.C.C., as it keeps the internal capa- merely a concentrated form of indue-
   city down                                 tance and has no special tuning pro-
                                             g;';fiaé which will enable you to dis-
      J. C. M. (Gretna), who at times has        se with>a tuning condenser. (2)
   trouble to receive-the concerts from           sed 'as an audlofrequency ampli-
   Melbourne, asks: (1) Would placing     - fier you need not fear the generation
   of ATI close to a stone wall in the of radio frequency oscillations, but if
   room affect the signals? (2) Would used in the reflex cireuit as deSCribed
   better results be obtained using a 7/20 by Mr. Reed in No. 5 issue of
   lead to earth instead of No. 16 copper ‘“‘Radio,”’ you can determine if it is
   wire. (3) What is wrong with circuit oscillating by tapping the grid ter-
   (sketch submitted).                       minal, when a dull click will be heard.
      Answer: (1) Probably your coils        (3) Yes, if local.conditions are fav-
   are affected by the atmospherie ourable. (4) The aerial bears no re-
 ~ humidity. Treat them according to ]atlonshlp to the valve used.


 one, ‘‘that the quality      eiTVS         SHEPHERD
the price is forgotten.’’
rell-balanced, -correétly
touch of individuality
                                            &NEWMAN
                                            COMPLETE PRINTING JENVICE
 business.
                                              TYPOGRAPHIC ARTISTA
TAN LTD.                                      COMMENCIAL COLON AND