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INTRODUCTION 
The HeathkitModelHD-10 ElectronicKeyer uses 
solid-state (transistor) circuitry to provide 
clean, "bounce-free" keying. It will produce 
self-completing dots and dashes at speeds ad- 
justable from 
15 
to over 60 words per minute. 
(Alternate connections provide a speed range of
10 to 20 words per minute.) 
Transmitters that use grid-block keying, or 
other types of keying where a negative (bias) 
voltage 
is 
shorted to ground to key the trans- 
mitter, can be used with the Electronic Keyer. 
A built-in audio generator and speaker allows 
you to monitor the keying of the transmitter. 
Also a speaker-muting headphone jack ispro- 
vided in case you prefer to use headphones for 
monitoring. When using headphones you can 
also listen to the received signal without exter- 
nal switching. Screw terminals areprovided on 
the rear of the Electronic Keyer for connecting 
to the headphone output of the receiver. 
Keying is accomplished with a keying lever and 
two small snap-action switches, onefordotsand 
the other for dashes. For dots, the keying lever 
is moved to the right; for dashes, the keying 
lever 
is 
moved to the left. This keyingsequence 
can be reversed by simply reversing the con- 
nections to the snap-action switches. 
The Hold position of the slideswitchcanbe used 
to continuously key the transmitter fortuning or 
other adjustments. Also, you can connect a 
straight or speed key to the Electronic Keyer 
for conventional nonautomatic keying. 
b 
Normally, the Electronic Keyer 
is 
operated 
from a standard 105 to 125volt AC line. How- 
4 
ever, there are provisions for battery opera- 
tion for emergency service. Operation from a 
230 volt 50 or 60 cps AC line 
is 
alsopossible 
by adding a suitable capacitor (not supplied) 
in 
series with one side of the AC line. Informa- 
tion on battery and 230 volt operation is in- 
cluded in the Installation section of the Manual. 
The Electronic Keyer will prove tobe a valuable 
and most versatile addition to your other ama- 
teur radio equipment. When youbecomefamiliar 
with its use, you will undoubtedly improve the 
clarity of your 
CW 
transmissions and the con- 
venience of operating. 
complete informationonunpacking, tools, wiring, 
soldering, and step-by-step assembly proce- 
dures.