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1994-11-27
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5KB
From the files of the ARRL Automated Mail Server, (info@arrl.org):
Provided as a courtesy by: N4TMI
Archived as a membership service by the American Radio Relay
League, Inc., Technical Information Service.
file: \public\info\tis\2010.txt updated: 03-29-93
Thank you for requesting the following information from the ARRL
Technical Information Service or the ARRL Automated Mail Server
(info@arrl.org). ARRL HQ is glad to provide this information free
of charge as a service to League members and affiliated clubs.
For your convenience, you may reproduce this information,
electronically or on paper, and distribute it to anyone who needs
it, provided that you reproduce it in its entirety and do so free
of charge. Please note that you must reproduce the information as
it appears in the original.
If you have any questions concerning the reproduction or
distribution of this material, please contact Michael Tracy,
American Radio Relay League, 225 Main St., Newington, CT 06111
(email: mtracy@arrl.org) or the original source or author.
----------------------------- cut here --------------------------
From: Michael Covington <mcovingt@ai.uga.edu>
Subject: Repair of the Sony ICF-2010
Date: Thu, 11 Mar 1993 17:25:41 -0500 (EST)
Content-Length: 3219
The following document, which I wrote a while ago, answers a question
that SWLs frequently ask. You are welcome to distribute it if you'd
like. I am an ARRL member.
--
:- Michael A. Covington internet mcovingt@uga.cc.uga.edu : *****
:- Artificial Intelligence Programs phone 706 542-0358 : *********
:- The University of Georgia fax 706 542-0349 : * * *
:- Athens, Georgia 30602-7415 U.S.A. amateur radio N4TMI : ** *** **
HOW TO DETECT AND REPAIR THE
COMMONLY BLOWN TRANSISTOR IN THE SONY 2010
Michael Covington, N4TMI
(Free distribution; you are welcome to copy and distribute
this document.)
As is well known, transistor Q303 in the front-end of the Sony
ICF-2010 general coverage receiver is easily damaged by static
electricity. Here is information on how to diagnose and fix this
problem.
WHAT ARE THE SYMPTOMS?
A 10- to 20-dB loss of sensitivity on AM (longwave, medium wave, short
wave). If you have a good antenna you may not even notice the loss.
In all other respects the radio functions normally.
HOW DO I TEST IT?
If you buy a used 2010 it's a good idea to perform this test even if
you do not notice a performance problem.
Remove the back cover and locate transistor Q303, near the antenna
input. Identify its three terminals (D, G, and S).
Now measure the voltage from each of those terminals to ground, with
the receiver turned on and receiving shortwave. (The negative lead
from your voltmeter should go to the outer sleeve of the antenna jack.)
The voltages should be: S 0.2V G 0.0 V D 2.9 V
Note especially the drain (D) voltage. If it is substantially lower
than 2.9V, the transistor is leaky. (Mine measured 1.6V when defec-
tive.) If it's substantially higher (like 4.5V), the transistor is
open.
HOW DO I FIX IT?
The popular MPF-102 transistor, available at Radio Shack, is a
suitable replacement. (Sony used a 2SK152, not widely available in
the U.S.A.) Simply unsolder the old transistor and install the new
one, then check voltages again. No alignment is necessary.
HOW DO I PREVENT FURTHER TROUBLE?
By connecting the shortwave antenna through a protective diode network,
as shown below.
\|/ Antenna
|
+-----------+--------+----------------------------> tip of plug
| |
\ / --- Sony 2010
--- / \ Four 1N914 or antenna
| | 1N4148 diodes jack
\ / --- (do not substitute)
--- / \
| |
+-----------+--------+----------------------------> sleeve of plug
|
-------
-----
--- Ground (optional)
The diodes limit all voltages going into the receiver. Use the
specified types; other kinds would produce loss of signal, signal
mixing (resulting in image frequencies), or both.
The 2010 has a built-in protective diode network connected to the
built-in telescoping antenna but not the antenna jack. (At least,
that is true of the original design. I have not been able to confirm
whether the design has been modified in more recently built 2010's.)
The ARRL members and HQ staff would like to thank the following people
for their contributions to this information file:
N4TMI
Send any additional information or changes to mtracy@arrl.org.
73 from ARRL HQ.