Concerning SB-401's Relay #1 (RL-1)

[W6CUX]

1. That black stuff on the relay contacts is silver oxide which is a very
good conductor and does not need to be removed.

2.
*******************************************************************
January 29, 1974
SB-401      Bulletin No:
SSB Tranmitter     SB-401-2

                                                       Relay RL-2 Hang-up

After a period of transmission, the relay remains in the transmit
[energized] mode, rather than returning to the receive [de-energized]
mode.

This problem is caused by gassy 6146 output amplifier tubes.  When these
tubes become hot, there is enough secondary emission from the screen
grids to keep RL-2 energized.

The solution is to ground lug 7 of RL-1.  This grounds the 6146 screen
grids in receive, thus preventing the secondary emission current flow
from holding RL-2.  The SB-401 manual will be revised to reflect this
change in new production.
****************************************************************************
***
Stu W6CUX

----- Original Message ----- 
From: "Robert Myers" <rsmyers at ROGERS.COM>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Wednesday, August 24, 2005 10:57 AM
Subject: [HEATH-TEMPE] Concerning SB-401's Relay #1 (RL-1)


Hi everyone,

Two questions concerning the SB-401's Relay #1  (RL-1, the multipole relay
that clicks ON when the Morse key is keyed down, or the '401 is switched to
TUNE --- not the antenna relay):



1.  What are the contacts made of?  All mine look completely black.  Is that
normal, or should I give them a half second dunk in TarnX then quickly rinse
them all off thoroughly with Anhydrous 100% concentrated Isopropyl Alcohol?
I'm asking about TarnX because I've used DeoxIT on them, and washed them
with SuperWash (MG Chemicals), and they still look all black to me.

2.  There is a recommendation to ground pin 7 of this relay (not in my
original manual).  How important is that?  Did anybody do this and find it
fixed a problem?  If so, what was the problem you had before doing that?

 Thanks,

--- Rob VE3JQL

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