LETTER TO <SANITIZED> FROM FRED J. MORRIS RE LOOKING FOR THE SPURIOUS PULSES

• Document Type: FOIA
• Collection: FOIA Collection
• Document Number (FOIA) /ESDN (CREST): 05752618
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 2
• Document Creation Date: March 9, 2023
• Document Release Date: February 10, 2021
• Case Number: F-2011-01575
• Publication Date: October 12, 1967

Approved for Release: 2021/01/13 C05752618
12 October 1967
(b)(3)
ATTN: J.W.
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Gentlemen:
In response to your phone call we suggest looking for the spurious pulses in the
following manner:
1. The most probable cause of target-like pulses with no target present is transients
on the 28 v dc and 400 cps power lines. Procedure to identify this source is to look
at the power input to the W-system breakers with an oscilloscope and attempt to
correlate transients with the system response. Transients on the power lines can be
generated by tuning on and off other systems � the 5 kw, for example.
2. The second most probable cause is tuning capacitor breakdown. We have
observed an occasional arcing at the small valued capacitor. This will affect the
stability of the coil driver and can be observed at the input J 204 pin H inside the
control monitor box. The control box must be operational to perform this test
(don't unplug).
- Another check on coil driver stability can be obtained by setting the switch on
the control monitor panel to the REF position and observing the VU meter for small,
instantaneous changes in deflection.
3. The third most probable cause of spurious pulses is mechanical in nature. The
following items should be checked:
a. Loose screws, or other metal in stinger.
b. Nuts (plastic) on sensor and coil locking devices.
(b)(1)
(b)(3) 10 USC 130
4. Other than these the problem gets more complex but the following can be
accomplished easily.
THEgleCtt40 Iffedtattia
Approved for Release: 2021/01/13 C05752618
COMPANY
Approved for Release: 2021/01/13 C05752618
12 October 1967
Attn: J.W.
Page 2
a. Watch the null to see if field bucker and associated circuit is stable.
This is accomplished by setting the front panel switch to NB (position
4) on control monitor and observing the VU meter. If it goes in and
out of null fast, lock down sensor and coil. If it slowly goes in and
out of null, a bad component in the field bucker circuit, which is in
the control monitor box, is indicated.
b. Any one of the regulated power supplies could have gone bad.
c. Either of the output filters could be bad � one drives the remote meter
and the other drives the strip-chart recorder. A response on one channel
and not the other indicates the malfunctioning filter. We had this
trouble once before and traced it to a FET.
Other than these as possible sources, a much more thorough analysis would be required
to identify the intermittent signal source. We are prepared to travel to the equipment
for the purpose of performing any maintenance or repairs that may be required.
Sincerely yours,
THE ELECTRO-MECHANICS COMPANY
Fred J. Morris
Director of Research
FJM:mw
Approved for Release: 2021/01/13 C05752618