[Amps] Intermittent AL-811H SWR problem

[Jack Berry]

Sorry Colin, I did mean <60 watts, not amps.
It's the radio that is seeing the intermittent SWR, not the amp. With the amp 
totally pulled out of chain, the SteppIR never presents more that 2:1 for the 
most part. 

I have checked the SO-239 for bad joints, and have replaced the jumper between 
the radio and amp with new coax and connectors. That hasn't eliminated the 
problem either.
I do notice that the problem doesn't come up on a cold amp but seems to 
eventually happen once the amp is in operation for a few minutes (10 or more).

Thanks for the response. Hope this offers a clue or two.

73,
Jack - WE5ST

Message: 5
Date: Fri, 24 Feb 2012 20:45:00 -0600
From: Jack Berry <jlberry at yahoo.com>
Subject: [Amps] Intermittent AL-811H SWR problem
To: "amps at contesting.com" <amps at contesting.com>
Message-ID: <0F319A02-F0BD-464C-8C40-5C1BD4F24577 at yahoo.com>
Content-Type: text/plain;    charset=us-ascii

I'm driving the 811H with <60 amps from a K3 into a SteppIR beam. I'm seeing 
high SWR (as much as 24:1) come and go. 

Changed interconnecting coax, etc.
With the amp out of the lineup the SWR  is fine. 
The reading I've done seems to say the tubes are failing. But I would think the 
problem would stay if that were the case. 


Any ideas?

Thanks & 73,
Jack - WE5ST 


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Message: 6
Date: Fri, 24 Feb 2012 18:49:03 -0800
From: "k7fm" <k7fm at teleport.com>
Subject: Re: [Amps] Intermittent AL-811H SWR problem
To: "Jack Berry" <jlberry at yahoo.com>,    <amps at contesting.com>
Message-ID: <23AC59775DA84C77A13698A779398D62 at COLIN>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
    reply-type=original

I'm driving the 811H with <60 amps from a K3 into a SteppIR beam. I'm seeing 
high SWR (as much as 24:1) come and go.
Changed interconnecting coax, etc.
With the amp out of the lineup the SWR  is fine.
The reading I've done seems to say the tubes are failing. But I would think 
the problem would stay if that were the case.

Any ideas?

Do you mean less than 60 watts?  You say you are seeing a high SWR.  Where? 
Is it between the k3 and the amp or the amp and the SteppIR?  Hard to 
diagnose if we do not know the facts.

73, Colin  K7FM