Interesting discussion.
Usually relays have better reliability than specifications indicate, but
QSK operations do put a lot of stress on them.
The sequence "TEST W6WRT TEST" contains a total of 6+16+6 = 28 binary symbols
which each consists of one make and one break cycle of the relays.
If this is repeated 2000 times, a minimum of 56000 + other transmissions, say
80000 cycles, would result for one contest.
A reasonable actual life expectation for the average vacuum relay, assuming
cold switching, is 4 - 5 million cycles, so it may be possible to wear out a
relay in 50 - 70 or less contest occasions.
73/
Karl-Arne
SM0AOM
----Ursprungligt meddelande----
Från: dezrat1242@yahoo.com
Datum: 2013-11-10 06:31
Till: "Amps"<amps@contesting.com>
Ärende: Re: [Amps] Best source for Gigavac GH-1 ?
ORIGINAL MESSAGE: (may be snipped)
On Sat, 09 Nov 2013 20:54:37 -0800, Jim wrote:
>
>That would have a lot to do with the use they get. How many contest QSOs
>do you make in a year? I do a lot, and after the second time having to
>replace relays in the middle of a contest, I've switched to
>semi-breakin. :) I use Ten Tec Titans, which are well sequenced.
>
>73, Jim K9YC
REPLY:
The math is interesting. The relay is rated at 2 million operations.
Sending TEST W6WRT TEST is 13 characters
I can easily sent that 2000 times in a contest plus exchanges any S&P
That's 24000 relay operations at a minimum
2,000,000 / 24000 = 84 contests not including whatever other operating you
do.
Conclusion: QSK with a relay is expensive.
PIN diodes might be a good alternative, but they have their problems too.
73, Bill W6WRT
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