[1000mp] Bad Antenna Relay? (long)

[Tod - MN]

In some cases if relay contacts never carry current (less than 1 ma) =
with
time "something happens" and they seem to develop a surface resistance =
that
acts to reduce the signal transmitted through them. I have a vague
recollection that by running a very small current (about 1 ma) through =
relay
contacts when they are closed the contacts will remain 'clean'.

=20

In some respects this seems to describe some of the anecdotal data =
points
expressed on the reflector. If the contacts are mechanically burnished =
by
switching I suppose that the surface resistance might be cleared as =
well.=20

=20

I have absolutely no idea how we would test this idea with our 1000MP's =
(or
variants thereof). I guess one would have to look at the circuit diagram =
and
figure out how to run a small current through the RX contacts without =
losing
signal. Since the error mode is not present in every MP, it may be that =
it
is a function of the type or lot number of the relays that were used in
production. It would not be the first time that a 'bad' lot of =
components
made its way into a production line. In fact, if it was not recognized =
that
a certain percentage of the components had attributes that caused RX
problems, the specifications for the component would remain the same and =
the
component would be used in many production runs. Since the problem =
occurs
very, very infrequently it would not be surprising if the relay
specification did not specifically deal with long term contact =
resistance.
Further, if the cost of specifying, testing and incorporating a =
different
relay was high enough to increase the product cost above a certain
threshold, the manufacturer might choose to make no change.

=20

I suppose this is the ultimate horror story from a manufacturer and =
user's
point of view -- that the failure mode appears in only a small =
percentage of
the production units and that simplest cure seems to be to replace a =
single
component which resolves the problem in most cases. In a few cases one =
might
expect that a 'not entirely good' component is used to replace the =
original
'not entirely good' component and a few folks are in the position of the
simplest cure not being a cure for them.=20

=20

My personal experience with Japanese and American manufacturers is that =
they
(or their lawyers) are loathe to declare that there are any flaws one of
their products. The may be willing to 'deal with a product that does not
perform the way they think it should' as long as they do not need to
publicly declare that they might need to make an engineering change.=20

=20

=20

I wonder if anyone else has the same assessment of the 'Bad Antenna
Problem'?

=20

Tod, K=D8TO

=20

=20



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