Heathkit GD 1B Schematic Manual

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dial is at approximately lhe middle ol the band, the adiustmcnl will probably be sulfimenl [or
any lrcqucncy selling wllhln the band.

mmm. My V: a sr-ulvm .ll.

5 . c

mm... (ouplmg I. . can

A

50-1: 5 ,
cw», Mm. .. Wm

c-nm, um." n
a.

D
B

DETERMINING AN UNKNOWN CAPACITY

Unknown values of capacity between '20 and 2,000nul can readily be mmsnred Will} the grid dip
meter. The unknown cundenscr should be placed parallel Willi the 14-37 mc (toil, designated as
coil C on Page l9 oi this manual, the coil (nus forming a parallel Circuit.

Depending upon the suspeciPd value of the unknown cundensvr (5043 graph on Page 5) the 2-5 nr
5-14 mc coil, dcsignaled as A 0r 1}, should be plugged 1:11.0th instrument, Set (he DIODE-05C,
SWHCh to OSCILLATOR position. Couple quile closely [he coil ol 2 parallel resonant circuit
containing the unknown condenser and tune the GD-lB through the [requcncy range. when [he
diphns been deiecled, reduce the cuupling solhal (he dip shows up overa very narrow lrequoncy
band, A! maximum dip, read the lrequency indicated on the dial and {rum me graph, read the
value a! (he unknown nondensen A glance al the graph will reveal mat condensers under 65 mil
are not covered. To deiermine values in this range, an exlrn rapnrllnr Di about 100 mi! shmnld
be usedl II it is no! a precision capacitor, its valus can be determined by me method uuilined
abovel Once its value is known, it should be canneried in parallel Wllh the unknown condenser
and the 14-37 mc coil "C". Using this method, [he iolal Capamly ni lhis Lest Ceru is deter-
minedl The value 0! the unknown condenser is {he dillerence between me total capacity in the
test circuit and the value of the known added condenser.

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