[AMPS] Alpah 77DX rcve bypass problem

[Phil Clements]

Better yet, since the problem os on receive, jumper around the reed
relay contacts with a clip lead  after you get the problem initiated with
no RX. If the reed relay is stuck, RX will be restored. You can jump
the vacuum relay the same way from the top without having to remove
the bottom panel, but be careful on the placement of the clip lead as
4 KV is very near by!

GL!

(((73)))
Phil, K5PC

Rich Measures wrote:

> >
> >
> >Lost the receive path somewhere in the Alpha 77DX just before the end of
> >the WPX test this past weekend.  The direct/aux slide switch has been
> >by-passed so that isn't the problem. Transmit works fine. receive had
> >always worked fine before.
> >
> >What I've seen so far: Antenna is routed fine from a cold start and thru
> >the 3 minute warmup. The first time it keyed it after that, it took a 1/2
> >second or so to get rcve back, next slightly longer and then quickly
> >refusing to work after that. Thumping the case had no effect. If you shut
> >the amp off, the rcve will come back in a few (5 to 15) seconds maybe.
> >
> >What to suspect? Well the vacuum relay is about the only thing in the
> >path. So measuring the pull down point (Q301) on the QSK board showed that
> >to operate fine (55 volts pulled low when keyed, then comes back up
> >quickly). I thought if something was leaking here it might keep the relay
> >switched in tx, but that doesn't seem to be the case.  Yet something is
> >keeping it energized as shutting the amp off lets the relay go back to
> >receive.
> >
> >I haven't a spare vacuum relay to pop in, but that seems like the obvious
> >thing to do, but in the meantime, anyone have any other thoughts? Residual
> >magnetism holding it on or??
> >
> -  my vote is for residual magnetism, Don.   As I recall, there is a reed
> relay in addition to the vacuum relay.  I would interchange the wires
> leading to the relay coils.
> -  cheers
>
> Rich...
>
> R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>
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