UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
SCHEDULE 13G
(Under the Securities Exchange Act of 1934)
(Amendment No.)*
KEITHLEY INSTRUMENTS, INC.
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(Name of Issuer)
COMMON STOCK
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(Title of Class of Securities)
487584104
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(Cusip Number)
December 31, 2007
_______________________________
(Date of event which requires filing of this statement)
Check the appropriate box to designate the rule pursuant
to which this schedule is filed:
[X] Rule 13d-1 (b)
[ ] Rule 13d-1 (c)
[ ] Rule 13d-1 (d)
*The remainder of this cover page shall be filled out for a
reporting person's initial filing of this form with respect to the
subject class of securities, and for any subsequent amendment
containing information which would alter the disclosures provided in
a prior cover page.
The information required in the remainder of this cover page shall
not be deemed to be "filed" for the purpose of Section 18 of the
Securities Exchange Act of 1934 ("Act") or otherwise subject to the
liabilities of that section of the Act, but shall be subject to all
other provisions of the Act (however, see the Notes.)
[Continued on the following page(s)]
Page 1 of 5 Pages
CUSIP No 487584104 Page 2 of 5 Pages
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1. Name of reporting person
S.S. or I.R.S. identification no. of above person
Babson Capital Management LLC
51-0504477
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2. Check the appropriate box if a member of a group
(a)( )
(b)( X )
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3. SEC use only
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4. Citizenship or place of organization
Delaware
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5. Sole Voting Power
730,000
Number of -----------------------------
shares 6. Shared Voting Power
beneficially
owned by 0
each -----------------------------
Reporting 7. Sole Dispositive Power
person
with 730,000
-----------------------------
8. Shared Dispositive Power
0
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9. Aggregate amount beneficially owned by each reporting person
730,000
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10. Check if the aggregate amount in row (9) excludes certain shares*
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11. Percent of class represented by amount in row 9
5.27%
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12. Type of Reporting person
IA
CUSIP No 487584104 Page 3 of 5 Pages
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SCHEDULE 13G
ITEM 1(A): NAME OF ISSUER:
KEITHLEY INSTRUMENTS INC.
1(B): ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:
28775 Aurora Road
Solon, Ohio 44139
ITEM 2(A): NAME OF PERSON FILING:
Babson Capital Management LLC (Babson Capital)
ITEM 2(B): ADDRESS OF PRINCIPAL BUSINESS OFFICE:
470 Atlantic Avenue
Boston, MA 02210-2208
ITEM 2(C): CITIZENSHIP:
See Item 4 of Cover Page
ITEM 2(D): TITLE OF CLASS OF SECURITIES:
See Cover Page
ITEM 2(E): CUSIP NUMBER:
See Cover Page
ITEM 3: TYPE OF REPORTING PERSON:
If this statement is filed pursuant to Sections 240.13d-1 (b)
or 240.13d-2 (b) or (c), check whether the filing person is a:
(e) [x] An investment adviser in accordance with
Section 240.13d-1 (b) (1) (ii) (E)
ITEM 4: OWNERSHIP:
(a)AMOUNT BENEFICIALLY OWNED: Babson Capital, in its capacity as
investment adviser, may be deemed the beneficial owner of 730,000
shares of common stock of the Issuer which are owned by investment
advisory client(s).
(b) PERCENT OF CLASS: 5.27%
(c) For information on voting and dispositive power with respect to the
above listed shares, see Items 5 - 8 of Cover Page.
CUSIP No 487584104 Page 4 of 5 Pages
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ITEM 5: OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS:
N/A
ITEM 6: OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON:
Cobbs Wharf Fund LLC 5.27%
ITEM 7: IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH
ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING
COMPANY:
Not Applicable
ITEM 8: IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP:
Not Applicable
ITEM 9: NOTICE OF DISSOLUTION OF GROUP:
Not Applicable
ITEM 10: CERTIFICATION:
By signing below I certify that, to the best of my knowledge and
belief, the securities referred to above were acquired in the
ordinary course of business and were not acquired for the purpose of
and do not have the effect of changing or influencing the control of
the issuer of such securities and were not acquired in connection
with or as a participant in any transaction having such purpose or
effect.
SIGNATURE:
After reasonable inquiry and to the best of my knowledge and
belief, I certify that the information set forth in this statement
is true, complete and correct.
Date: February 14, 2008
Signature: // Jan F. Jumet //
JAN F. JUMET
Senior Compliance Officer
CUSIP No 487584104 Page 5 of 5 Pages
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February 14, 2008
Securities and Exchange Commission
Operations Center
Attn: Stop 0-7
6432 General Green Way
Alexandria, VA 22312-2413
Re: SCHEDULE 13G RELATING TO COMMON STOCK OF KEITHLEY INSTRUMENTS
FOR THE YEAR ENDING DECEMBER 31, 2007
Dear Sir or Madam:
Babson Capital Management LLC is filing today an initial Schedule
13G through the EDGAR system as required by Section 240.13d-1(b)
to reflect beneficial ownership of greater than 5% of the outstanding
stock of the above-mentioned issuer.
Please note that the shares as to which this Schedule is filed are
owned by various investment advisory clients of Babson Capital,
which may be deemed a beneficial owner of the shares only by virtue of
the direct or indirect investment discretion it possesses pursuant to
the provisions of investment advisory agreements with such clients.
A copy of the Schedule 13G is being sent to the issuer as required by
Rule 13d-7.
Comments or questions concerning the above may be directed to the
undersigned at (617) 761-6599
Sincerely,
// Jan F. Jumet //
JAN F. JUMET
Chief Compliance Officer