From Wireless Marketing Corp.
90% of the radios returned to us for service have failed as a result of
people untrained in electronics tampering with the radios. Most of the information available on how to get more out of your
radio is passed on by people who use the trial and error approach. They seldom understand the consequences or what they are
Here is some REAL info on those consequences.
Quite a number of radios have come back to us with internal settings in
the same position. These adjustments have caused most of the failures seen on these radios.
First of all. The bias adjustment does not work like a volume control,
it controls the idle current and centers the signal in the amplifier so that neither the top or bottom of the signal is cut
of and there is a minimum of DC current flowing through the transistor so that it does not heat up wasting power that is not
part of the output signal. Virtually all of the radios returned for blown finals had this mis-adjusted.
Second, The bias on the driver transistor has a peak when it is
set right. If it is turned too far it will lower the output on the SSB signals. It is critical for good performance. SSB modulation
cannot be set properly without looking at the signal on an oscilloscope. Just turning things up while looking at a power meter
will end up with a signal that so badly garbled that people won't understand you. All of the sets returned for garbled SSB
had this turned all the way up.
Third, a common problem is losing RF gain control and then losing
receive sensitivity. Radios that have had the ALC ( called the "limiter" by people uneducated in any electronics school )
disabled put out such a chopped up signal that the diode protection that turns off the receiver during transmit can't protect
the input transistors. People have been blowing out their own receivers by trying to get "more modulation".
Fourth and worst of all, some people have been adjusting, the power
supply in an attempt to get more out of the radio. It should be set for 13.7 volts. The front panel lamps are 14 volt bulbs,
and if they are burning out it is a good chance that this has been turned up. This is nothing compared to what is happening
to the rest of the radio. All of the transistors are being weakened and it is just a matter of time before your radio is good
for nothing better than a doorstep.
Think for a minute. Would you hold a rubber band in your teeth
while somebody showed you how far lie could stretch it before it broke? That is what you are doing when you do things or have
them done to your radio. Most of these "secrets" being circulated are pure hogwash. They are like those ads that tell you
to send them money and they will send you info on how to rig your car to use water as fuel. There are always consequences
to any modification or mis-adjustment . That is why any tampering voids the warranty.