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[Towertalk] WX0B Six-Pack

To: <>
Subject: [Towertalk] WX0B Six-Pack
From: (Bob Henderson)
Date: Wed, 19 Jun 2002 08:12:36 -0000
I am a little overwhelmed at the number of replies my enquiry has generated.
At least as many direct to me as through the reflector.  Thanks everyone,
your comments are much appreciated though too numerous to reply to

A number of points have been raised and questions asked.  I hope you will
forgive my composite response.

The PSU I have been using is a 20A 13.8V switch mode unit.  With internal
adjustment I got this up to 14.5V.
At this setting the Six Pack continued to be unreliable.  I measured the
voltage across each relay coil when activated and found it to be 14V so my
resistive path loss was 0.5V.  When I say I measured the voltage across the
relay coils I mean just that, at the coil terminals on the relays
themselves.  Alas, I have not been able to measure the voltage when the
circuit has failed as this only happens very occasionally and on failure
physical contact with the Six Pack restores it to working order.

My problem is not just with one relay or one cct but with several.  If it
was one I would have just changed the relay and said nothing.  Several
circuits fail though most often I have trouble with the 160m and 15m ccts.

I don't think there is anything untoward in the psu but just in case the
switch mode doesn't like light weight inductive loads I have now switched to
a 7A 13.8V linear supply which I have anyway adjusted up to 17V.  So far the
box continues to work reliably but it's still early days.  Remember, the
problem is intermittent and would typically happen maybe a couple of times
in a 48 hour contest.

It was suggested that failure maybe an environmental issue.  The Six Pack is
in the shack where it is typically around 27C and about 40-65% RH.

It was suggested the relay box should be mounted upright and not be laying
on its back or side for reliable operation.  I didn't know that and if it's
true then that could be my problem as I have the Six Pack on its back on the
floor here.  Perhaps it's time I drilled some holes in my shack wall.

It was suggested by a man who worked on large relay switching systems for a
living, that if you have to start playing around with adjustment of spring
tensions on open frame relays you should throw them away as they will never
be reliable.  I adjusted mine on Jay's advice.  Jay told me it was necessary
to adjust the spring tensions to find the point at which the relays would
open with adequate force to wipe the N.O. contact effectively, whilst at the
same time close properly with a 12V supply.  It appears there is no such
point on several of my relays!  I am no expert on relays although I have
used a few in my time, but it seems to me that when a relay spring is set
with the appropriate tension to open the relay contacts effectively, then
the specified operating voltage should provide effective closure with a
significant margin.  Put simply, if the relay is a 12V unit then it should
close, though not necessarily reliably, at less than 8V.   My experience
with the Six Pack is that when spring tension is adequate to provide good
wiping and hence good continuity through the N.O. contacts then 12V isn't
enough to activate the relay. Could this because I have the unit lying on
its back on the floor?  I dunno!

My current arrangement has the relay springs adjusted to provide good wiping
on the N.O. contacts (I hope!) and I have 16.5V across activated coils to
overcome the spring tension.  There is the risk that after prolonged use I
may burn out a relay coil but I'll have to deal with that if and when.

It has been suggested that Jay may have had a bad batch of relays or perhaps
some 18V units marked incorrectly as 12V.  Perhaps.  I will check the relay
coil resistances when I next open the box up.  If and when it next fails.

In conclusion I should point out that there are apparently many satisfied
users of Six Packs out there.  Five people have told me this and commented
on just how reliable their particular Six Packs have been.  Five other folk
have said that they have experienced similar problems to me.  Some have
resolved the issue by changing relays and others by increasing supply

Sincere thanks again to all for your various advice and your interest in
this.  I will now wait to see if the unit is now more reliable.


Bob 5B4AGN, P3F, ZC4ZM

----- Original Message -----
From: "Bob Henderson" <>
To: <>; <>
Sent: Tuesday, June 18, 2002 2:00 PM
Subject: Re: [Towertalk] WX0B Six-Pack

> Good thought Kevin but not the problem here.  My supply leads are of 5 Amp
> twin cable only 3 feet long.  I measured the voltage across an activated
> relay coil and it was 14V but still operation was unreliable.  Since then
> I've changed the PSU and now I'm using 17V.  So far operation is reliable
> but it's early days yet.
> I still think a 12V unit should work reliably when there's 12V across the
> relay coils.  Maybe I'm just old fashioned. :-))
> 73
> Bob 5B4AGN, P3F, ZC4ZM
> ----- Original Message -----
> From: "Kevin Adam" <>
> To: "Bob Henderson" <>
> Sent: Tuesday, June 18, 2002 1:22 PM
> Subject: Re: [Towertalk] WX0B Six-Pack
> > Change the wire size it's to small and you not getting enough current to
> the relay.
> > you have the voltage until the current starts to do it's thing then you
> only get the job
> > done half way. the wire size feeding the relay is to small.
> >
> >
> > On 18 Jun 2002 at 6:17, Bob Henderson wrote:
> >
> > > I am wondering if any Six-Pack users out there are experiencing the
> > > same problem I am.
> > >
> > > I have found my Six Pack to be rather unreliable.  The problem is that
> > > the relays don't always operate in such a way that a reliable contact
> > > is made. The typical failure is that one or other of the relays fails
> > > to pull in properly.  I spoke to Jay at Array Solutions and he told me
> > > that the spring tensions on the relays needed to be adjusted to ensure
> > > that there is enough tension to cause the necessary wiping action on
> > > the N.O. contacts.  At the same time this tension has to be not so
> > > great that it overcomes the capacity of the relay coil to cause the
> > > relay to close properly when power is applied.
> > >
> > > I have adjusted endlessly but I have not been able to find a reliable
> > > operating set-up through this adjustment.  It seems to me that when
> > > increasing spring tension I find the point that prevents relay closure
> > > before I find the reliable N.O. contact wiping tension.
> > >
> > > It seems to me, though Jay disagrees, that there is a design flaw in
> > > the Six-Pack.  I have used DX-Engineering and Top Ten Devices switch
> > > boxes at the top of towers in hostile environments for years and never
> > > had a problem. This Six-Pack sits in the shack at the back of my
> > > operating desk and it is so unreliable!  At least it is close enough
> > > so I can give it a kick when a relay doesn't pull in properly.
> > >
> > > To me that the idea of a fine adjustment of relay spring tension to
> > > find a position where the relay reliably closes but at the same
> > > setting will open with the necessary force to properly wipe the N.O.
> > > contacts has no place to be on an antenna switch.  Surely this is
> > > marginal design?
> > >
> > > On my previous antenna relays I have found that nominal 12V relays
> > > would operate with as little as 8V applied which meant that with 12V
> > > applied the really clunked in well.  With these units there was no
> > > delicate adjusting of spring tension either....they wiped the N.O.
> > > contacts reliably from day 1.
> > >
> > > Does anyone share my experience or have I just got a one off
> > > unreliable Six Pack?
> > >
> > > 73
> > >
> > > Bob 5B4AGN, P3F, ZC4ZM
> > >
> > >
> > > _______________________________________________
> > > Towertalk mailing list
> > >
> > >
> >
> >
> >
> >
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