Topband: TX relays

Tom W8JI w8ji at
Thu Oct 9 22:54:17 EDT 2014

>> Between contact and coil. I just took 2 photos:

This is where dissection helps. We can see, from the pictures, that relay is 
likely a good relay.

1.) It has wide smooth current paths. It does not have wire leads

2.) It has good spacing and insulation from contacts to the coil and metal 
outside the contacts

3.) It appears to be, although I am not certain, a gold flash.

Gold (real gold flash) is ideal for the receiving end as long as it is not 
hot switched or arced. Silver is not. Some silver alloys are worse still, 
and materials that appear in relays designed to be hot switched at high 
current are terrible in our applications (unless we only transmit).

When people burnish contacts, they rub the gold off. This is why a WD40 
wetted hard paper is about the most abrasive thing that should ever be used 
as a cleaning tool.

There is a problem with relays enclosed in plastic, like the picture. The 
plastic can leech contaminants that spoil the connection at low currents. 
Brand new relays exhibit this issue. Usually it clears and eventually stays 
OK once some very small current is passed through the contacts.

This is a frustrating problem for new equipment, because the relay can be OK 
in testing until it sits a while.

73 Tom 

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