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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.5577 / Virus Database: 4223/8645 - Release Date: 11/28/14
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|