Posted by
n6wg on
Feb 12, 2006; 5:09pm
URL: http://elecraft.85.s1.nabble.com/K2-Relay-contact-resistance-tp386534p386543.html
Hi Stewart
I have K2 s/n 12 in pretty constant use here, particularly in contests.
So far as I can tell, I have no problem with the relays, either in the
basic K2 or in the KAT2.
Good luck and 73
Bob N6WG
Teh Little Station with Attitude
-----Original Message-----
From:
[hidden email]
[mailto:
[hidden email]]On Behalf Of Stewart Baker
Sent: Sunday, February 12, 2006 4:24 AM
To: Elecraft Reflector
Subject: [Elecraft] K2 Relay contact resistance
Having decided to join the melee trying to work 3Y0X on Peter One Island, I
dusted off my FT1000MP. The only time that I use it are on occasions such as
this when a separate receiver is useful when working split.
I noticed that the receive sensitivity was varying on 20 & 40m, and traced
this
to the HPF board at the front of the receiver. This board contains 8
miniature
relays which do the filter switching. If I tapped the board the received
signal
strength varied. From notes I found on the web this is a known problem where
the
solution is to change all 8 relays. I didn't fancy changing these small
relays
if there was a better solution.
I remembered that the FT102 had big problems with people were changing
relays by
the bucket full. Yaesu don't seemed to have learned the lesson of the FT102
!
A local amateur came up with a fix which consisted of running a small DC
current
through the contacts to break down any oxide layer that had formed over
time.
This morning I modified the HPF board to run about 1mA through the contacts.
10 resistors and 2 caps later - End of problem - Fixed....
The big relays in the KAT100 should not have a problem, but what about the
smaller ones in the K2, KAT2 ? As far a I can tell a number of these have
only
very small AC signals passing through them. None have any DC current flow.
It took about 7 years before the problem surfaced with my FT1000MP, I would
be
interested in comments on whether in the same time scale I might expect to
get
similar problems with my Elecraft gear.
73
Stewart G3RXQ
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