While I totally agree with the comments on the poor performance and life of
the contacts on open frame relays, my experience with noise from relay
switching has been that it is usually a failed snubber capacitor or diode
across the relay coil. Occasionally, especially with rotary switches, the
cause has been arching on the switch contacts.
zeke ab8ou
On Tue, Feb 22, 2022 at 5:07 PM Grant Saviers <grants2@pacbell.net> wrote:
> Small signal, dry contact relays are made from different contact
> materials than power relays made for higher voltages and currents. Any
> fix that cleans them or removes the surface oxide that inhibits low
> voltage signal transmission will likely be temporary. Plus the high
> power relays are prone to generating noise and have a large bounce.
> Except for mercury wetted ones, bounce is common on all relays.
>
> Grant KZ1W
>
> On 2/22/2022 13:41, Michael Tope wrote:
> > Steve,
> >
> > Does the switch produce an S9 spike on any transition of the switch
> > (i.e. from position N to position N+/-1) or only on a certain subset of
> > switch transitions? That might provide a clue as to whether there is a
> > problem with one of the relays or the power supply that energizes them.
> > I am wondering if it could be a bad filter capacitor in the relay
> > control circuits or a bad DC blocking cap over on the switch end.
> >
> > I am not convinced that dirty relay contacts could cause the noise
> > spike, but it is probably agree to clean the relay contacts anyway just
> > in case. W8JI recommended soaking a piece a paper in a liquid
> > hydrocarbon (I think he used Xylene) and then passing that paper between
> > the contacts of the relays in order to transfer any foreign material to
> > the paper without causing undue abrasion to the relay contacts. I've
> > done this and it has fixed the problem of an RCS-4 going deaf on receive
> > despite still working for transmit. For receive only applications you
> > might have to do it more often.
> >
> > 73, Mike W4EF...........
> >
> > On 2/22/2022 10:04 AM, Steve London wrote:
> >> I am using an Ameritron RCS-4 antenna switch to select between beverage
> >> antennas. Recently, it has developed a bad case of relay bounce
> >> causing an
> >> S9 spike every time I switch between antennas. Any suggestions on how to
> >> improve this ? Since it's only used for RX antenna selection, I'm
> >> amenable
> >> to replacing the relays with something else, although I have had issues
> >> before with other relays due to no current going through the contacts.
> >>
> >> Thanks and 73,
> >> Steve, N2IC
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