Rich wrote:
> >
> >Gerard M0AIU/AA3ES wrote:
> >
> >> hope you are not into CW contesting. A vacuum relay has a life of
> >>about 2 million operations. A serious CW contester will wear it out
> in 6
> >>days! And that is when the relay was purchased new.
>
> Anybody who sends 2 million dits and dahs in 6 days is destined for
> the
> nut-house. If you need longer contact life, purchase the (tungsten
> contact) RJ-1H instead of the RJ-!A
>
I didn't come up with the 2 million number Rich, you did. I posted a
very simple calculation on the reflector on the 11th of February. In
case you forgot, here it is again:
Let us assume:
* 50 % TX/RX duty cycle (i.e. a 'run' station in a contest)
* 35 wpm
* 50 units per word ('Paris' standard)
* 14 relay operations per word (based on 'Paris', using full
break-in QSK)
* 35 (wpm) * 14 (operations/word) * 50% * 60 (min/hour) = 14700
operations per hour
* 2 million operations / 14700 operations per hour = 136 hours
* 136 / 24 = 6 days
Vacuum relay life is very roughly about three contest weekends
Back then, you decided not to respond to it. Probably because you never
did the (very simple) calculation yourself. This (not making the obvious
calculations) is something you constantly accuse other people of. But as
you can see, 2 million operations in 6 days is not that unlikely. I
think you have been able to get away with it for so long, because the
vacuum relays will actually survive much more than 2 million operations,
but that is just your luck. Maybe somebody who is using CW-QSK could put
a counter across his relays, and let us know how many relay operations a
decent CW contest weekend produces (by that I mean somebody who makes at
least 2500 QSO's, not the DX hunter who tunes across the bands and
manages 125 QSO's in 48 hours).
How long does a tungsten version last?
> >
> >I have been using some RF1 vacuum relays for switching the amp
> available a
> >few years back here at all the hamfests at about $7-50 each, new.
> (You can
> >tell we're not in Nebraska!)
>
> amen
>
> >They were arranged so that the bias doesn't
> >come off the grid until the output relay has gone over: they are
> energised
> >for receive. I do not run QSK, but got a strange effect that received
> >signals would all go T4, and the received signal levels would drop.
> Tapping
> >the relay with a pencil would restore things.
>
> This is most likely due to residual magnetism in the armature . The
> usual fix is to reverse the wires to the relay coil.
>
Is this Californian black art again?
> Rich...
>
Cheers
Gerard..................................
AA3ES / PA3DQW / M0AIU
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|