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Dlginsc
Posted on Saturday, September 21, 2002 - 7:43 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I have a 4-tube Elkin am/ssb amp that I accidently keyed up too many watts into. It blew a resistor on the bridge below the tubes. I replaced the resistor. But now, when I key up the amp, it won't unkey. Any suggestions? Thanks.
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2600
Posted on Thursday, September 26, 2002 - 1:39 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

What you are looking for is a small transistor and one or two small glass diodes. They will be somewhere in the back between the radio jack and the relay. So far as I know, nobody has ever seen a schematic diagram for an Elkin linear. When you cross-reference the part number from the keying transistor, be sure the legs are wired in the same pattern. The new one may have the three legs E, B and C arranged differently than the original. Little generic glass signal diodes like 1N4148 from RatShack should be okay substitutes for the original ones. Just pay attention to which end has the black (or white) band painted on it. The polarity matters on them, too.

If you still get power from the thing, this could be the only remaining damage. I would suggest checking the tubes in a tester to make sure you didn't cripple one of them. If it is running on 3 tubes out of four, that's not good for the other three.

73
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Dlginsc
Posted on Thursday, September 26, 2002 - 9:41 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Thanks 2600,
I believe you are correct on the schematics. I was thinking it might be the keying transistor also. I will check on it and the diodes. I will recheck tubes also. Thanks for the help.

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