A little follow-up on the "relay bounce". It's certainly possible that I
have mischaracterized the problem.
I have a newer version of the RCS-4. It has sealed, enclosed relays (P&B
RTE24012F). There are no back-EMF diodes or capacitors across the relay
coil. Unfortunately, the SO239's are riveted (not screwed) to the plate and
they used a large blob of solder to connect each one to the board. Adding
diodes/capacitors is not trivial. As an experiment, I bypassed the bias-T
configuration and ran the control voltage on a separate wire. Alas, that
reduced the switching spike by 90%. I think that does point to the relay
coil back-EMF getting into the RF line.I will note that there is a 220 uF
electrolytic across each relay coil.
Thanks for all the suggestions.
73,
Steve, N2IC
On Wed, Feb 23, 2022 at 4:13 AM <ok5mm@post.cz> wrote:
> Hello,
>
>
>
> I have been using FTR-K1 Series power relay for a years...see attached
> document.
>
>
>
>
> 73 from Vit, OK5MM
>
>
>
>
>
> ---------- Původní e-mail ----------
> Od: Allan Zadiraka <ajzadiraka@gmail.com>
> Komu: Grant Saviers <grants2@pacbell.net>
> Datum: 23. 2. 2022 4:55:33
> Předmět: Re: Topband: Relay bounce
> "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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