If you simply remove the tube and problem persists, it's not the tube. Given
what you saw, I doubt the tube is the problem.
Kim N5OP
"People that make music together cannot be enemies, at least as long as the
music lasts." -- Paul Hindemith
> On Nov 28, 2014, at 14:37, "Jim W7RY" <w7ry@centurytel.net> wrote:
>
> Or a shorted tube will take out the step start fuse and resistors.
>
> 73
> Jim W7RY
>
>
> -----Original Message----- From: Carl
> Sent: Friday, November 28, 2014 12:49 PM
> To: John DiLorenzo ; amps@contesting.com
> Subject: Re: [Amps] AL80-B fuse F101 blown;step-startnot working?
>
> The first thing Id check is to see if the relay contacts are welded,
> Ameritron uses the wrong contact alloy for high current use. Also check that
> the step start circuit is wired per the manual as Ameritron amps had a
> history of miswiring that could take out the transformer going back to the
> AL-80A and larger amps. Dont expect to find Ameritron issuing a bulletin or
> admitting a problem.
>
> If the relay is good then disconnect the HV AC from the rectifier circuit.
> If the fuse blows again then the transformer is likely cooked or there is a
> problem on the optional jumper terminal strip.
>
> Carl
> KM1H
>
>
>
>
> ----- Original Message ----- From: "John DiLorenzo"
> <john.dilorenzo33@gmail.com>
> To: <amps@contesting.com>
> Sent: Friday, November 28, 2014 2:48 PM
> Subject: [Amps] AL80-B fuse F101 blown;step-startnot working?
>
>
>> I acquired this amplifier about two weeks ago, and when I received it,
>> neither theforward nor reflected power meters would indicate anything. As a
>> "test", Ireplaced the detector diodes (D114 and D115) with 1N914s as these
>> were diodes I had on hand. My intent was to see if the meters would at
>> least register something, and if so, order the correct diodes (1N34s).
>> Well that worked,so I ordered the diodes.
>>
>> They arrived, so I replaced the 1N914s with the correct 1N34s. With the
>> unit all buttoned up again, I noticed while tuning up, the meter lamps
>> would dim, and the HV would sag significantly. I wanted to test and record
>> some values when the amp shut down completely; this is what I had to that
>> point:
>>
>> HV
>> (volts) Ig
>> (mA) Ip
>> (mA) Standby 3050 0 0 Keyed, no drive 3050 0 0 CW, 5W drive 2700 20 125
>> I discovered that F101 had blown in the amp. This fuse is in series with
>> the step start resistor, so it seems my step-start was staying in the "low
>> current" mode, and when I keyed the amplifier, this 2A fuse blew as
>> expected. I'm just not sure what broke. The diodes I replaced aren't near
>> the rectifying diodes that pull the step-start relay. Any insight into
>> common failures, where to start looking, or how to debug?
>>
>> Thanks in advance,
>> John, K8DIL
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>>
>>
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