On 11/16/2017 7:28 PM, rickman wrote:
Gareth's Downstairs Computer wrote on 11/16/2017 4:01 PM:
On 16/11/2017 20:04, rickman wrote:
Gareth's Downstairs Computer wrote on 11/16/2017 12:55 PM:
On 16/11/2017 17:07, rickman wrote:
Bob Wilson wrote on 11/7/2017 9:47 PM:
On 11/4/2017 5:42 AM, Gareth's Kitchen Komputer wrote:
On Mon, 21 Dec 2015 23:33:17 +0000, gareth wrote:

For those who make their own Morse Keys, what do you use for the
contacts,
for
I have found the phosphor bronze pillar for the dot contact on
my ersatz
Vibroplex
to be very noisy and scratchy?

I'm fairly sure that I asked this question before, but it has
been a
habit
of never put off till
tomorrow what you can put off till the day after.

I chose phosphor bronze because in the days of making one's own
electronic
organs, phosphor bronze was suggested as a suitable keying
matreial for
the
keyboards.






If a question's worth asking, Gareth...







I have not made lots of keys, but when I do I use contacts from old
relays.
I still have some relays I bought as WWII surplus when I was in my
teens,
back in the 1950's. They have strange coil parameters, weird mounting
arrangements, etc., but nice little silver contacts.
Bob W, WA9D

Why use a mechanical switch?Â* There are magnetic hall effect switches
around.Â* Or a mercury wetted switch can be operated by a magnet.
Are the
magnetic switches too sloppy?


Perhaps you confuse mercury wetted with reed relays?

I am thinking of reed relays, so I guess I used the wrong name, but
aren't
they wetted with mercury to prevent corrosion building up?


In the closed atmosphere of the glass tube, there should not be any
corrosion, I think. ISTR some gas in there, but don't know about
mercury wetting.

Call it what you want, corrosion, oxidation, just plain pitting.Â* The
point is a solid surface will wear from the arcing that happens when
contacts break connections (which also happens on initiating connection
because of switch bounce).Â* Mercury doesn't have this problem as it is a
liquid and reforms the layer every time it is "pitted".


Mercury also does not make a "clean" break. It "puddles" as the
contacts are pulled apart due to surface tension. It leads to irregular
break timing. This isn't a problem at low switching speeds as you have
in regular switches and relays, but can be at higher rates as in CW.
Additionally a magnetic field for switching accentuates this problem.
Reed relays are good for things like security system contacts, but not a
CW key.


--
==================
Remove the "x" from my email address
Jerry Stuckle

==================