Running any kind of paper currency or?business card or the like will only help the RF rx side of the switch contacts which are the NC contacts. ?NO or NC contacts on the??armature contacts C on the bias can develop a “ pit” and “tit” scenario on the contacts. ?They can not be clean with any miracle spray goop of paper treatment. ?A mild file is needed to fix up those contacts and followed with a buffing. ?If done correctly contact surface can be?successfully?restored. ?The contact flashing isn’t?needed so much on the bias contacts as it is needed on the NC contacts in the receive path! ?Dentron amps are specifically?prone to the issue. ?I’ve had to restore damaged bias contacts several times before.
On Thursday, November 30, 2023, 7:18 PM, Steve <k0xp@...> wrote:
Very often, all that is necessary is to run a bizness card
between the contacts. A card with a particularly-rough finish is
great, but don't use a card with an epoxied smooth or glossy
finish on one side. If you do, then try to stick a sheet of
ordinary notebook paper to that side of the card so it doesn't
contact the relay contacts. The epoxy or gloss may rub off onto
the relay contact and make the problem even worse.
When you run a bizness card thruogh the contacts and examine it,
you will notice gray or black residue is left on the card.
However, the card will not clean up a burned or pitted contact
very well.
73,
Steve K0XP
On 11/30/2023 3:46 PM, Dave w6de wrote:
There
are burnishing tools for exactly this purpose.?
Using finger nail files and files for this purpose is
risky, as the potential damage of removing too much contact
material is high.
?
I
have one of these:
Here
are two more:
?
?
Burnishing
tools have very fine almost invisible teeth.?
Using a burnishing tool is a safe method for cleaning
relay contacts.?
Every radio amateur that works on equipment with open
frame relays should have one in his tool kit.
?
73,
Dave,
w6de
?
?
John,
you just might have a worn out contact that switches bias on
the antenna relay. ?If the contacts are severely pitted they
might not make up too good sometimes and other times ok.
?You need to inspect the that set of contacts in particular.
?If you carefully remove the rear spring on the relay you
can lift the armature off and inspect all the contacts. ?The
contacts that switch the RF can be cleaned gently, the
contacts on the bias may be in bad shape, there may be a
tiny point on the armature contact and a tiny depression on
the body contact. A gentle filing to remove the “pit” and a
cleaning should restore reliable contact. ?It’s not unusual
at all to see the bias contact hood bad with the age of thst
amp especially being used on CW a lot. ?Seen it quit often
and by doctoring up the bias?contact that problem went away.
?Lou
Sent from
the all new AOL app for iOS
?
On Thursday, November
30, 2023, 3:58 PM, John Roland <johnroland51@...> wrote:
--
See my QRZ.com page at
