[Amps] AL1200 weak receive

[Ed Swiderski, KU4BP]

Okay. Will look at it again today with your suggestions.

Thank you.

On 7/30/2022 9:34 AM, gudguyham--- via Amps 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!!!!!!
>
>
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>
> 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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