>
>> I know Tom W8JI has worked closely with Ameritron in the past. I
>> wonder if he might know how that relay was spec'ed or if there is any
>> history on it he could share with us.
>
>Hi Dick,
>
>I didn't have a chance to answer the original question, but let me
>give a general reply about relays...since it will apply to ANY
>amplifier and ANY antenna switch and be useful to anyone dealing
>with signal switching relays of ANY type. This includes 4-squares,
>remote antenna switching systems, and indoor devices like
>amplifiers.
>
>The relay is the amplifier is the same family of relays used for the
>last 30 years by almost everyone, Drake, Collins, Heathkit,
>Dentron, etc. You find that relay or family of relays in RCS-8's and
>many other antenna switches.
>
>The most common complaint is failure to receive signals without
>attenuation, or intermittent receive. In order of most commonly
>seen problems:
>
>1.) The contacts have tiny specks of solder flux spattered on the
>contacts when people solder around them. You should ALWAYS
>cover the contacts when soldering in the area of the relay. In this
>case you should use a glossy PAPER soaked in a pure light
>hydrocarbon like methyl ethyl ketone, a paint reducer, xzyelne, or
>even pure alcohol (not stuff mixed with water) and draw it through
>the contacts several times with the contacts held against the
>paper.
>
>2.) The relays get specks of dust or other insulating trash between
>the contacts. In this case you should simply degrease the
>contacts with a fast evaporating pure clean solvent and blow them
>out with high pressure air.
>
>3.) Smoke deposits or a film of contaminants (common in the
>disgusting smelly equipment used by smokers, or in industrial
>areas). In this case they need cleaned like above.
>
>The most common thing everyone "screws up" is they remove the
>gold flashing off the contacts by cleaning the relay with an
>abrasive, like a contact file. If you use an abrasive, you have
>trashed the relay. The gold flash is necessary because there is NO
>contact current on receive. Without contact current, the relay can't
>"burn" through any garbage. (Burning through the garbage is why
>sometimes when your receive is out and you "bump" power through
>the contacts it restores the receive.)
>
>Another big problem is the contacts, in order to handle 10-15
>amperes on transmit, are designed wrong for handling almost zero
>current on receive. That's an engineering conflict relay designers
>are VERY familiar with.
>
>By the way, Ameritron is gradually switching to a compact
>hermetically sealed high-current miniature relay. ...
// It seems to me that a solution to contact problems is to use a
rhodium-gold contact relay. Out of >300 people who use the Matsushita
RSD, DPDT, Rh-Au contacts, 1mS, cellphone relay in their amplifiers , no
one has reported a failure.
> ... ...
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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