Re: ICF2010 sensitivity test? 


Oops! Forgot to include this (quoting Michael Covington, N4TMI--and I
should have gotten his permission to report this!)

"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,
shortwave). 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?

Retract the whip antenna.
Tune the 2010 to 1620.0 kHz and note the amount of hiss coming from
the speaker.
Tune the 2010 up, to 1620.1 or higher If you notice a drop-off in
the hiss level, the front end FET is OK. If the hiss level remains
the same between 1620.0 and 1620.1, the FET has been damaged.

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 by removing the 7 screws that are marked with
arrows. (One is inside the battery compartment.) Leave the computer
batteries in place 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. (A convenient ground
connection is the outer part 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
defective.) 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."

Be really careful with that soldering iron here. You can easily melt
the plastic case of the 2010, and the wires coming off the ferrite bar
are tiny! And I suggest soldering in a socket to make future FET
repairs a lot easier.

Michael N1XTV