[Amps] AL1200 weak receive

[Curt Nixon]

I was saying it can't be welded contacts because the relay does its job and
returns to rx when the op switch is in stay.  Does this with the relay
cable pulled out.  This was reported and tested twice by the owner.  I
agree with you that something internal is completing to ground on the
coil...the jack, the wiring  the bypass cap, or perhaps the relay coil
itself.

On Sat, Jul 30, 2022, 9:34 AM gudguyham at aol.com <gudguyham at aol.com> wrote:

> No, it is the case!  The ONLY way the rx can be lost if the switch is in
> operate is if the antenna relay line is shorted to ground and the rx signal
> is fine in standby.  It’s very simple to determine if the antenna relay is
> grounded in operate and that is to check for plate idle current.  That
> said, if the ptt line is shorted all you need to do is pull the ptt line
> out.  If the rx is restored then the ptt line is shorted or the radio has
> welded contacts or a shorted transistor just like Jim suggested.  If the
> relay still engages when the ptt line is pulled out then the negative side
> of the relay is shorted to ground inside the amp.  DO NOT go inside the amp
> unless the relay is activating with no ptt line plugged in!!!!!!
>
>
> Sent from the all new AOL app for iOS
> <https://apps.apple.com/us/app/aol-news-email-weather-video/id646100661>
>
> On Saturday, July 30, 2022, 8:59 AM, Curt Nixon <radio.ku8l at gmail.com>
> wrote:
>
> Don't think that is the case since he gets receive ok when the op switch is
> off.  Really needs to isolate the relay coil to see if the coil is shorted
> to ground or it is wiring to the jack
> Acts the same with relay cable pulled out so not the cable.
>
>
> On Fri, Jul 29, 2022, 11:17 PM Jim W7RY <jimw7ry at gmail.com> wrote:
>
> > Which would indicate that the relay in the radio has its contacts welded
> > together (or its transistor or FET shorted).
> >
> > 73, Jim W7RY
> >
> >
> > On 7/29/2022 4:45 PM, Mark Bitterlich via Amps wrote:
> > > Try unplugging the PTT line from the amp and see if the problem goes
> > away. Sounds like when you are going to "operate" on the front panel,
> there
> > is a path to ground from the relay coil. Either inside the amp, or the
> PTT
> > cable going to the radio. To confirm you could unsolder one side of the
> > relay coil, etc. Markwa3jpy
> > > -------- Original message --------From: "Ed Swiderski, KU4BP" <
> > ku4bp at triad.rr.com> Date: 7/29/22  12:33 PM  (GMT-05:00) To:
> > amps at contesting.com Subject: [Amps] AL1200 weak receive I have a
> > confusing problem with my AL1200. During operation when the stdby/oper is
> > on, the received signal is very weak. Switching back to standby and the
> > signal level is fine. Checked the relay and it was operating correctly.
> > Engaging with 12v applied to it. With no power to the amp and a rx signal
> > going through, manually engaging the relay weakens the signal. Releasing
> it
> > and it's back to normal. Cleaned the contacts using the method described
> by
> > W8JI on his site. Still no go. Stumped on where to look next to track
> this
> > down. A tests on another radio produced the same results.With no power to
> > the amp, I connected my RigExpert analyzer to the "RF in" and a dummy
> load
> > to "RF out". Doing a sweep, the SWR reads around 1:1. Engaging the relay
> by
> > hand shoots the SWR very high. Goes back down when released.That's the
> best
> > symptoms I can give. Any suggestions would be an immense help.Thank
> you,Ed
> > KU4BP_______________________________________________Amps mailing listAmps
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> > --
> > Thanks and 73, Jim W7RY
>
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