Tom, et al
The problem I experience was that while there was voltage getting to the
relay it wasn't quite enough to effect closure of the relay - in my case you
could give the box a whap and that would cause the relay to close - or as I
mentioned - upon inspection I found that when energized it took just the
tiniest amount of persuasion for the relay arm to make the trip to
closed...it was on the edge - the spring was just more than it could
overcome....
Like 5B4AGN's, this would occur on multiple bands (although some were more
often than others) so I felt that was not a bad relay per se....my lazy
solution to increase the voltage has done the trick and the box has worked
flawlessly for about a year now - my switchbox is inside the shack and the
leads from the control box to it are roughly six feet - I doubt voltage drop
is the culprit!
Again - with the increased voltage it works like a champ....dunno how anyone
could live without one!
73,
Jim, K4OJ
----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: <towertalk@contesting.com>; "jljarvis" <jljarvis@adelphia.net>
Sent: Wednesday, June 19, 2002 7:11 AM
Subject: Re: [Towertalk] sixpack relay problem
> > Privately, I observed that the most likely problem was
> > IR drop, or a bad relay. Let me repeat it publicly:
>
> The most common problem (by far) seen at Ameritron and other
> companies that use relays in hard-wired applications is flux
> contamination of contacts.
>
> It's pretty tough to get a high-resistance connection via separate
> control cables. I often just twist wires out in the field, and have
> thousands of feet of control wire! In 12 volt systems, you can
> usually tolerate dozens of ohms of loop resistance in control lines.
> I have systems switching multiple parallel relays reliably at 2500
> feet, just using thin telephone-type wire. I can't imagine a case
> where a 3-foot wire would have enough resistance to cause unreliable
> or "soft" switching.
>
> Personally, I'd check and clean the contacts. Hopefully they are gold
> flashed, or at least silver plated. You do NOT ever want a high
> current relay designed for switching operating loads, because the
> contacts will make bad connections after time.
>
> Clean the contacts by taking a hard paper like thin smooth semi-gloss
> cardboard (sometime on matchbook covers) and soak it in WD-40 or some
> other cleaner and rub it between the contacts. When you are done
> clean it with 100% pure alcohol or a very light cleaner like Toluene,
> Methyl Ethyl Ketone (MEK), or Xylene.
>
> Tension should be set so the relay pulls in at about 50-70% of rated
> voltage.
>
> Virtually any relay that is working at all, and has not had the
> contacts ate up by switching during high-power operation or arcing
> from lightning, will be 100% repairable using the above methods.
>
> Even brand new relays are subject to flux contamination, so
> replacement should be as a last resort.
>
> I don't know how Jay does the ground return, but I always make the
> ground common with coaxial cable grounds so the shields augment or
> entirely can replace the ground wire.73, Tom W8JI
> W8JI@contesting.com
>
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