Vertex Standard VX-520U, Service Manual, Page: 1 / 52

1
Introduction
The VX-520U is a compact hand portable transceiver
for the UHF land mobile band that offers the convenience
of small size, light weight, and simple operation. The
VX-520U can be simply programmed by your
VERTEX STANDARD Dealer with up to 32 channels for
single and split frequency operation. The VX-520U pro-
vides up to 5 watts of RF output power and includes a
flexible quick-connect antenna.
The transceiver and Ni-Cd battery packs are construct-
ed of thick high impact polycarbonate plastic, with spe-
cial attention paid by the designers to tight sealing and
ruggedness, assuring years of reliable operation even in
harsh environments.
The following pages describe the operation, features
and accessories of the VX-520U. With proper care and op-
eration, the transceiver will provide many years of reli-
able communications.
©2003 VERTEX STANDARD CO., LTD.
Service Manual
UHF Hand-Held Portable
Land Mobile Transceiver
VX-520U
Contents
Operating Manual Reprint .......................... 2
Specifications ................................................. 8
Exploded View & Miscellaneous Parts .... 9
Block Diagram ............................................. 11
Circuit Description..................................... 13
Alignment ..................................................... 15
Interconnection Diagram ........................... 19 Board Unit (Schematics, Layouts & Parts)
CNTL Unit .............................................................. 21
LCD Unit ................................................................. 29
VR & PTT Unit ........................................................ 31
Main Unit ................................................................ 33
APC Unit ................................................................. 39
PLL Unit .................................................................. 41
REG Unit ................................................................. 44
IF Unit ...................................................................... 46
VCO Unit ................................................................. 48
TCXO Unit .............................................................. 50
VERTEX STANDARD CO., LTD.
4-8-8 Nakameguro, Meguro-Ku, Tokyo 153-8644, Japan
VERTEX STANDARD
US Headquarters
10900 Walker Street, Cypress, CA 90630, U.S.A.
International Division
8350 N.W. 52nd Terrace, Suite 201, Miami, FL 33166, U.S.A.
YAESU EUROPE B.V.
P.O. Box 75525, 1118 ZN Schiphol, The Netherlands
YAESU UK LTD.
Unit 12, Sun Valley Business Park, Winnall Close
Winchester, Hampshire, SO23 0LB, U.K.
VERTEX STANDARD HK LTD.
Unit 5, 20/F., Seaview Centre, 139-141 Hoi Bun Road,
Kwun Tong, Kowloon, Hong Kong