Section I Model 686C
Paragraphs 1-4 to 1-6
When the instrument is connected to a properly wired The following instructions should be followed for easy
power system this polarity will be maintained as in- installation of a rack model instrument (686CR) in an
tended. If the instrument is operated from a two equipment rack.
terminal receptacle, the identification of the grounded
power conductor is lost. The proper grounding of the 1) Remove the four (4) screws from the rear of the
instrument cabinet thus becomes important as a mat- instrument cabinet and slide the instrument forward
ter of good safety practice. from the cabinet.
2) Mount the empty cabinet in the equipment rack with
1-4. 230 VOLT OPERATION. four (4) oval head machine screws: two screws on
The @ Model 686C is usually shipped wired for 115 each side of the cabinet in the mounting holes approxi-
mately 1-3/4 inches from the top and bottom edge of
volts ac operation, but is quickly and easily converted the mounting flanges.
to operation from a nominal 230 volt 50/60 cps source.
To convert, remove two jumper wires between Al-A3
and M-A4 on the power transformer (Tl) and install 3) Raise the instrument chassis and slide gently into
the cabinet. Be certain the power cable passes freely
one jumper between terminals A2 and A3. Inaddi- through the hole in the rear of the cabinet.
tion, remove the jumper wire from the rear terminal
of the HIGH-VOLTAGE (H. V. ) fuse and reconnect to
the side terminal of the H.V. fuse. This side termi- 4) Fasten the instrument panel securely to the rack.
nal also has a pink lead attached to it.
5) Replace the four (4) screws at the rear of the cabi-
Do not change the size of either the MAGNET fuse or net (if desired).
the H.V. fuse. When operatingfrom a 230volt source,
the MAGNET supply and the fan operate on 115 volts NOTE
supplied by T1 primary windings which act as a 2:l This instrument weighs Over 100 pounds. If
auto-transformer. This additional loadis added tothe
normal load carried by the H. V. fuse and approxi- the rack installation is subject to vibration
mately offsets the expectedreduction in current due to or rough handling, additional means of sup-
port should be provided at the rear of the
230 volt operation. instrument. C
1-5. RACK MOUNTING INSTRUCTIONS. 1-6. BACKWARD-WAVE OSCILLATOR TUBE
When mounting a rack model instrument, leave at IN FORMATION.
least 3 inches clearance behind the air intake to The bwo tube used in this instrument is very expen-
insure proper air circulation. In addition, be cer- sive and has a shorter guaranteed life than conventional
tain that the air intake is not near another piece of tubes. It is suggested that the instrument be turned off
equipment which is discharging hot air in the vicinity when not being used to increase the useful number of
of the Model 686C air intake. hours service obtained from each tube.
1-2 00034- 1 |
ACEC
HEWLETT-PACKARD
