Heathkit SB-401 relay RL1
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| Aug 7th 2012, 22:09 | |
KapAceHighTotal Topics: 0 Total Posts: 0 |
I'm thinking of following a Heathkit recommendation to connect contact 7 of RL1 to ground to eliminate the problem of the transmitter remaining on transmit when I end transmission. This is due to "gassy" final tubes, the Heathkit bulletin states. Maybe I'm missing something, but going through the schematics, I come up with six poles for RL1, not five. I do see a contact lug on the RL1 on my SB-401 without any connection. Can I assume this is number 7? Don't know if there are any other contacts without a connection. This could be possible. Wonder if anyone has the connection diagram for RL1, or did the suggested fix. Thanks all. 73's KC2ZDT |
| Aug 9th 2012, 19:02 | |
W1VTSuper Moderator Total Topics: 0 Total Posts: 0 |
http://www.nostalgickitscentral.com/heath/Service_Bulletins/sb401.txt The Service Bulletin says to connect lug 7, not contact 7. It also says that this change was added to the instruction manual--it is quite likely that the modification has already been made. No, I wouldn't make the connection unless if I was absolutely sure as to what I was doing. You can easily make expensive mistakes and blow stuff up by mis-connecting tube wiring. Zack Lau W1VT ARRL Senior Lab Engineer |
| Aug 9th 2012, 23:55 | |
KapAceHighTotal Topics: 0 Total Posts: 0 |
Thanks Zac for your reply. Looking into this a bit further, there are two additional contacts (lugs) that are not connected. As you state, the mod may have been already made. So I am not going to attempt any changes unless I can come up ith the connection diagram for the relay. Also, it might not be possible without unsoldering a lot of the wires to this relay due to the high density of connections to it. Regards, Bob KC2ZDT |
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