Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: How to renew the contacts on a keyer?  (Read 3235 times)
ND6P
Member

Posts: 96




Ignore
« on: July 20, 2011, 07:09:25 PM »

I have an old Bencher keyer.  The contacts are worn and I have to clean them frequently.  Does anyone know of a way to renew/rebuild these contacts?
Logged
KE4ILG
Member

Posts: 150




Ignore
« Reply #1 on: July 20, 2011, 07:24:29 PM »

Perhaps others will be more helpful but I have to ask in what way are they worn?  I have two  benchers each over 20 years old. All I have had to do to clean the contacts is place a dollar bill between the contacts, press the paddle and then pull the dollar bill.  Thats why I ask how are they worn.  Also bencher may sell replacement parts.  73, Mike ke4ilg
Logged
KE3WD
Member

Posts: 5689




Ignore
« Reply #2 on: July 20, 2011, 07:28:12 PM »

Bencher stocks all parts for their keys (it is not a keyer, it is a key, or a set of paddles, but a keyer is an electronic device for forming the Morse Code characters) also MFJ sells parts as well.  

The contacts are likely sold already installed onto the larger part.  

But first try using a spritz of Deoxit onto a piece of white printer paper and then drag the paper through the contacts while it is still wet several times, then follow up immediately with a dry piece of the same paper.  The contacts are very likely not shot at all, but could be corroded or covered with something on their surfaces that is not conductive.  If you don't have Deoxit handy, try rubbing alcohol the same way, although that may not last as long.

After the contacts have been cleaned as per above, an old trick is to use a dollar bill to clean them every once in a while.  The dollar bill paper contains very mild abrasives, including silk and does a wonderful job on the Bencher contacts.  Just put the bill edge between the two contacts, lightly close the contacts and drag the bill through them.  

73
Logged
ND6P
Member

Posts: 96




Ignore
« Reply #3 on: July 21, 2011, 04:41:09 PM »

Yes, it's a key, not a keyer.  I shouldn't try ti ask questions after a hard day at work Smiley

I bought it used so I am not sure how old it is, etc.  It's an old Bencher IAMBIC with the spring that wraps around the pole in the back and the triangular clear plastic paddles.

I've done the paper cleaning thing.  I use ordinary paper with some WD-40 on it.  But after a month or so, it needs cleaning again.

It's not a key that I want to spend much money on.  If there was some trick to gold plate the existing contacts, that would be nice.
Logged
K7KBN
Member

Posts: 2814




Ignore
« Reply #4 on: July 21, 2011, 04:54:21 PM »

I sure wouldn't use WD-40 on the contacts; Deoxit is much better.  And why gold plating? Silver is a better conductor than gold, and silver oxide is very nearly the same conductivity as clean silver.
Logged

73
Pat K7KBN
CWO4 USNR Ret.
PA0BLAH
Member

Posts: 0




Ignore
« Reply #5 on: July 22, 2011, 02:14:55 AM »

Possibly the previous owner of the key used abrasive paper and removed the plating of the contacts.

When silver turns black on the air, it is, due to air pollution, coated with Silversulfide not silveroxide, and silversulfide does not conduct.

Some guys use as replacement relays contacts , those are often covered with Rhodium

It is possible to plate your contacts as a DIY activity, but it is tricky because you need very poisonous chemicals.  for gold electro plating.
« Last Edit: July 22, 2011, 03:40:46 AM by PA0BLAH » Logged
K0XY
Member

Posts: 69




Ignore
« Reply #6 on: July 22, 2011, 09:49:48 AM »

...hmmmm ? ...I've always used an Eraser...the kind that you purchase at any office supply store...not the one on the end of a pencil, but the hand held variety...the hand eraser typically has two different grits, I use the rougher grit for the hard work and then the finer grit for the final polish...works for me !
Logged
VA7CPC
Member

Posts: 2393




Ignore
« Reply #7 on: July 22, 2011, 11:30:44 AM »

. . .
I've done the paper cleaning thing.  I use ordinary paper with some WD-40 on it.  But after a month or so, it needs cleaning again.
. . .

The WD-40 is a bad choice -- it will leave an insulating film on the contact surfaces.

I think the Bencher contacts are _solid silver_.  The nice thing about silver is that silver oxide is a decent conductor.  If the points tarnish, they'll still work OK. 

Wet a cloth with alcohol (or DeOxit) and pull it through the gently-closed contacts.  Repeat a few times, especially if the cloth comes out dirty.  That's all you should do -- anything more risks damaging the contacts, or leaving an insulating film.

Many "contact cleaners" contain oil -- "seal oil", often.  The silver contacts should be _bare_, not oil-coated, for best results.

         Charles

PS - the same technique works for Vibroplex bugs, and is well-documented.
Logged
VA7CPC
Member

Posts: 2393




Ignore
« Reply #8 on: July 22, 2011, 11:37:28 AM »

With a Google of "silver sulphide resistance" I got this interesting paper:

http://www.connectorsupplier.com/tech_updates_Timron_ElectricalContactResistance_1-23-07.htm

Which says (among many other things):

Quote
Note that a contaminant layer, with a thickness of only a few nanometers on nickel or copper, leads to a large increase in contact resistance. Contaminant films on silver consist largely of silver sulfide tarnish. These contaminant layers fracture relatively easily and do not adhere well to the underlying metal. For these reasons, silver sulfide layers on silver are easier to disrupt and are deleterious to contact resistance only where the thickness is relatively large.

So silver sulphide may be nothing to worry about. 

            Charles
Logged
K3STX
Member

Posts: 1001




Ignore
« Reply #9 on: August 02, 2011, 04:45:32 AM »

I assume you guys mean use a NEW dollar bill! I am not sure there are many things filthier than a dollar bill on the entire planet! I use that little contact cleaner thing they sell on eBay, works fine. Looks like a piece of brown strap.

paul
Logged
PA0BLAH
Member

Posts: 0




Ignore
« Reply #10 on: August 02, 2011, 12:32:29 PM »

Hahhaha K3STX, you remember the time silver quarters were disappearing because the value of the metal of the coin including substraction  for melting were considerable more than a quarter dollar. Guys were convicted with their trunk filled up with silver quarters.

Well right now,  50 years later the same happens with dollar notes, A piece of writing paper has more value then the printed dollar bill.

Government is printing over a billion each day, so the chance finding a filthy one is minimal.

Wondering how long the Chinese people will accept this (way of handling starting with Cr not written out)

I remember the time I was hammering a silver coin to the size of a pancake and  using small pieces to repair key contacts. Putting it on the railroad and waiting for a train passing by was a faster method.

Bob
« Last Edit: August 02, 2011, 12:51:33 PM by PA0BLAH » Logged
WV4I
Member

Posts: 136




Ignore
« Reply #11 on: October 23, 2011, 06:15:33 PM »

Vibroplex sells a contact cleaner strip for about $5, p/n 405, should work on other keys with silver contacts. Bencher?
Logged
NN4RH
Member

Posts: 328




Ignore
« Reply #12 on: October 24, 2011, 04:49:41 PM »

I suspect more keys are ruined by people unnecessarily trying to "clean" the silver contacts than any other cause.

If there's intermittent or noisy electrical contact then they may need to be "cleaned" or replaced. But the contacts do not need to be cleaned just because they're a little dull looking. As others have said the silver oxide is not a bad thing. Pure silver is not supposed to be shiny.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!